[go: up one dir, main page]
More Web Proxy on the site http://driver.im/
Next Article in Journal
Bedrock Scour by Developed Rectangular Jet Impingement in Shallow Plunge Pools
Previous Article in Journal
Merging Knowledge for Water Supply with Alternative Energies for Stilt House Communities of Ciénaga Grande de Santa Marta
You seem to have javascript disabled. Please note that many of the page functionalities won't work as expected without javascript enabled.
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Water
Volume 16
Issue 23
10.3390/w16233431
water-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Preparation of Iron-Based Nanozymes and Their Application in Water Environment: A Review

by
Xingfeng Cao
1,
Gongduan Fan
1,*,
Shiyun Wu
1,
Jing Luo
2,
Yuhan Lin
1,
Weixin Zheng
1,
Shuangyu Min
1 and
Kai-Qin Xu
1,3,*
1
College of Civil Engineering, Fuzhou University, Fuzhou 350116, China
2
Fujian Jinhuang Environmental Sci-Tech Co., Ltd., Fuzhou 350002, China
3
College of Environment and Safety Engineering, Fuzhou University, Fuzhou 350116, China
*
Authors to whom correspondence should be addressed.
Water 2024, 16(23), 3431; https://doi.org/10.3390/w16233431
Submission received: 29 October 2024 / Revised: 20 November 2024 / Accepted: 26 November 2024 / Published: 28 November 2024
(This article belongs to the Special Issue Applications of Nanozymes and Other Nanomaterials in the Water Environment: Latest Advances and Prospects)
Browse Figures
Figure 1
<p>Schematic diagram of the preparation process of (<b>a</b>) Fe-MoS<sub>2</sub> nanozyme [<a href="#B45-water-16-03431" class="html-bibr">45</a>] and (<b>b</b>) MIL-88B (Fe, Ni) nanozyme [<a href="#B51-water-16-03431" class="html-bibr">51</a>].</p> "> Figure 2
<p>Pollutant degradation mechanism diagram of (<b>a</b>) FeCu-NC nanozyme [<a href="#B68-water-16-03431" class="html-bibr">68</a>], (<b>b</b>) Fe<sub>3</sub>O<sub>4</sub>@N-HollCS nanozyme [<a href="#B69-water-16-03431" class="html-bibr">69</a>], (<b>c</b>) FeMn/N-CNTs nanozyme [<a href="#B70-water-16-03431" class="html-bibr">70</a>], and (<b>d</b>) Fe<sub>3</sub>O<sub>4</sub>@CeO<sub>2</sub>/Tb-MOF nanozyme [<a href="#B71-water-16-03431" class="html-bibr">71</a>].</p> "> Figure 3
<p>Pollutant detection mechanism diagram of (<b>a</b>) NH<sub>2</sub>-MIL-101(Fe)@Cu/CeO<sub>2</sub> nanozyme [<a href="#B91-water-16-03431" class="html-bibr">91</a>] and (<b>b</b>) NH<sub>2</sub>-MIL-101(Fe) nanozyme [<a href="#B92-water-16-03431" class="html-bibr">92</a>].</p> ">
Versions Notes

Abstract

:
Nanozymes represent a new generation of artificial enzymes that combine nanomaterial properties with catalytic activities similar to those of natural enzymes. It has significant advantages in catalytic efficiency, selectivity, and stability, leading to increasing interest in their application in aqueous environments. Since the discovery of enzyme-like activity in Fe3O4, more and more iron-based nanozymes have been utilised for the detection and removal of pollutants. Iron is a non-toxic, low-cost transition metal, and this property makes iron-based nanozymes more compatible with safety requirements in aqueous environmental applications. Although iron-based nanozymes have demonstrated significant advantages in the water environment field, the relevant research is still in its infancy. Therefore, it is of great practical significance to systematically summarise the latest applications of iron-based nanozymes in the water environment. This paper describes the common methods of synthesising iron-based nanozymes. In addition, the applications of iron-based nanozymes in detecting pollutants and pollutant removal are reviewed. It was found that the removal of pollutants by iron-based nanozymes was mainly achieved through the reactive oxygen species, whereas the recognition of pollutants primarily depended on the reactions of iron-based nanozymes, such as colour development, fluorescence, and chemiluminescence. Finally, we highlight the challenges and future prospects for the application of iron-based nanozymes in water environments. In summary, this paper systematically summaries and discusses the common synthesis methods of iron-based nanozymes and their applications in the aquatic environment, with a view to providing new ideas for overcoming the limitations of traditional pollutant detection and removal methods and realising the high-quality development of iron-based nanozymes in water environment.

1. Introduction

Water is the basis of existence and the source of civilization, and environmental water protection has always been a priority for environmental protection. With rapid economic development, accelerated urbanisation, and improved living standards of the people, pollutants such as toxic ions, pharmaceuticals, dyes, pesticides, and phenolic substances are inevitably discharged into natural water bodies [1,2,3]. It has been reported that about 300–400 tons of heavy metals, toxic sludge, and other toxic chemicals are discharged into natural water bodies every year from all types of human activities, and that 80 percent of sewage is not treated in any way [4]. These pollutants are highly hazardous to humans and the environment. They can cause cancer, teratogenesis, mutagenesis, inhibition of reproduction, development of drug resistance, and alteration of gene expression [5,6,7]. More importantly, pollutants accumulate in organisms and the aquatic environment over long periods of time and are difficult to degrade naturally. Even trace levels can be harmful to the aquatic environment and human health [8,9,10,11]. Pollution detection and degradation technologies are the key to solving water-environment problems. However, traditional water treatment methods, such as biological treatment, chemical precipitation, ion exchange, membrane separation, coagulation, and adsorption, suffer from low efficiency, high cost, and susceptibility to secondary pollution [12,13,14]. In addition, achieving accurate detection of pollutants is a prerequisite for solving water-environment problems. Traditional detection methods, such as mass spectrometry [15], high-performance liquid chromatography [16], gas chromatography [17], atomic absorption spectrometry [18], fluorescence spectrometry [19], and electroanalytical methods [20], have been widely cited for the detection of pollutants in the aquatic environment. These methods usually have low detection lines and high sensitivity [21]. Nevertheless, traditional pollutant detection methods are characterised by expensive instrumentation, difficult on-site testing, and complex operation, making it difficult to effectively address the international community’s concerns about water safety [22].
Natural enzymes are biocatalysts with high catalytic activity, good substrate specificity, and excellent biocompatibility. They are widely used in environmental protection, healthcare, biosensing, food processing, chemical production, and agriculture [23,24]. Due to their specific catalytic action, natural enzymes have a unique position in pollutant detection and degradation [25,26]. However, the practical application of natural enzymes is constrained by many factors. On the one hand, natural enzymes are thermally and chemically unstable, and their activity is greatly affected by temperature, pH, organic solvents, and heavy metal ions [27]. On the other hand, natural enzymes are costly, have complex preparation, are highly demanding in the application environment, and usually do not work under harsh conditions [28]. In order to break through the above bottlenecks, nanozyme, a nanomaterial with natural enzyme-like activity, has been gradually developed as a good alternative to natural enzyme [29,30,31]. Compared to natural enzymes, nanozymes have the significant advantage of efficiently catalysing the conversion of enzyme substrates under mild conditions and exhibit catalytic efficiency and enzymatic reaction kinetics similar to those of natural enzymes. In the water environment, the nanoscale of nanozyme provides a larger specific surface area and more active sites, which makes it easier to absorb and degrade pollutants. Meanwhile, colorimetric and fluorescence reaction nanozymes based on specific substrates can effectively realise the rapid detection of pollutants. Moreover, nanozymes can also be combined with various composite materials, thus being applied to the ever-changing environmental problems. Since the pioneering work of Yan et al. in 2007 [32], nanomaterials such as noble metal nanoparticles [33], metal oxides [34], metal–organic frameworks [35], and layered double hydroxides [36] have been found to possess enzyme-like activities and are widely used for the detection and degradation of pollutants. Among them, iron is a non-toxic and low-cost transition metal, a property that makes iron-based nanozymes more compatible with the safety requirements in aqueous environmental applications [37]. More importantly, iron-based nanozymes have greater advantages in terms of their potential to catalyse the Fenton reaction, stability, and low cost [38].
The number of publications related to iron-based nanozymes has grown exponentially over the past few years. However, previous review articles related to iron-based nanozymes have focused on applications in tumour therapy, disease diagnosis, and biomedicine [37,38,39,40,41,42]. To our knowledge, a review of iron-based nanozymes for aqueous environment applications has not been reported. In order to fill this gap, we first summarise the common preparation methods of iron-based nanozymes and then review the application of iron-based nanozymes in the detection of pollutants and pollutant removal. Finally, we look forward to the possible breakthroughs of iron-based nanozymes in the water environment field and provide our viewpoints.

2. Preparation Method of Iron-Based Nanozymes

Iron-based nanozymes have successfully and effectively combined the environmentally friendly and low-cost properties of iron-based nanomaterials with the high catalytic activity of natural enzymes [37,39,43]. Scholars have developed a series of preparation methods to obtain iron-based nanozymes with certain specific properties or improve their catalytic activity. The most commonly used methods mainly include hydrothermal, solvothermal, and co-precipitation methods (Table 1).

2.1. Hydrothermal Method

The hydrothermal method, which dates back as far as 1882, is a synthetic method in which precursors are dissolved in an aqueous solution and then reacted at high temperatures and pressures in an airtight container to simulate the growth of crystals during mineralization in nature [43,56,57,58]. This method is commonly used for the preparation of oxides or water-insensitive compounds, which has the advantages of simple operation, low cost, and environmentally friendliness; the prepared products are characterised by narrow size distribution, high purity, high crystallinity, low aggregation, and controllable morphology; and it is one of the most commonly used methods for the preparation of iron-based nanozymes [58,59,60].
For example, Lin et al. synthesised a MoSe2@Fe nanozyme with excellent enzymatic and fluorescence properties by a simple one-pot hydrothermal method at 180 °C using Fe (NO3)3·9H2O, polyethene glycol 6000, ammonium molybdate, sodium selenite, and glutathione as raw materials [44]. Feng et al. obtained peroxidase-like nanozymes with significantly enhanced catalytic activity by simply doping iron on MoS2 nanosheets via a one-pot hydrothermal route [45]. Specifically, it was prepared by adding Na2MoO4·2H2O, L-cysteine, and FeSO4·7H2O as iron, molybdenum, and sulphur sources in 30 mL of water, respectively, and then reacted vigorously for 30 min at normal temperature and pressure, and then transferred to a reactor to react at 200 °C for 24 h to obtain Fe-MoS2 (Figure 1a) The experimental results showed that the Mo/Fe molar ratio directly affected the peroxidase-like activity of Fe-MoS2, which was optimal when the ratio was 3:1. In another study, Fe, N, and S co-doped carbon dots (Fe-CDs) nanozymes were prepared using a hydrothermal method using ferric chloride and sunset yellow as raw materials by Ahmad et al. The morphology of the Fe-CDs prepared by the hydrothermal method was a uniformly distributed spherical shape without significant aggregation and with a narrow range of particle size distribution (0.9–1.7 nm) [46]. In addition, Xu et al. synthesised Fe, N-CDs via the hydrothermal method using inexpensive and readily available histidine and ferric chloride as precursor substances, and the yield of the Fe, N-CDs obtained using this method was 7.4% [47]. Jiang and his team synthesised a ferromagnetic chitosan nanozyme (MNP@CTS) for the degradation of phenols and phenolic compounds using an improved hydrothermal method and molecular self-assembly technique, and the synthesised nanozyme is stable and can be recycled at least ten times [48]. Overall, the hydrothermal method is a promising method for the preparation of iron-based nanozymes. However, it still suffers from the disadvantages of demanding reaction conditions, safety risks, and limited applicability. Some reactants that are less stable in water or react adversely with water cannot choose the hydrothermal method as a synthesis method.

2.2. Solvothermal Method

The solvothermal method is a material synthesis method developed based on the hydrothermal method, a preparation technique for replacing the solvent in a hydrothermal method from water to an organic solvent [59,61]. The method inherits the features and advantages of the hydrothermal method but also makes up for the shortcomings of the hydrothermal method to a certain extent. The diversity of organic solvents allows a broader range of adjustment of the physicochemical properties of the reaction system, which can be adapted to the synthesis of more different types of materials. On the other hand, for some reactants that are less stable in water or react adversely with water, organic solvents can provide a milder and more suitable reaction environment to promote the smooth progress of the reaction, thus expanding the variety and range of synthesisable materials [62,63]. Therefore, the solvothermal method has been widely used to prepare iron-based nanozymes.
Using a solvothermal method, He et al. prepared FeS2-encapsulated COFs (FeS2@SNW-1) as novel peroxidase-like nanozymes [49]. Briefly, 4 mg of FeS2 powder and 313 mg of melamine were first ground and added into dimethyl sulfoxide (DMSO). Then, 15.5 mL of a DMSO solution containing 500 mg of 1,4-Phthalaldehyde was slowly dripped into it. The mixed solution was fully reacted under nitrogen protection for 2 h and then placed at 180 °C for 10 h. After the reaction, the FeS2@SNW-1 was washed and dried to obtain the FeS2@SNW-1. The experimental results showed that the affinity of the prepared peroxidase-like nanozyme for the substrate molecules was higher than that of the natural peroxidase. Huang et al. prepared mesoporous Fe3O4 nanoparticles using a solvothermal method and then loaded N-CDs onto Fe3O4 nanoparticles to form magnetic N-CDs/Fe3O4 nanocomposites, which possessed good peroxidase-like activity [50]. In another study, Sun et al. prepared a mixed solution of FeCl3·6H2O and p-dibenzoic acid as solutes and N, N-dimethylformamide as the solvent. Then, 2 mL of 0.2 M sodium hydroxide was rapidly added to the above homogeneous solution for a continuous reaction of 1 h and then transferred to an autoclave to obtain the nanozyme MIL-88B (Fe, Ni) [51] (Figure 1b). The nanozyme showed a regular multi-faceted cubic structure with a 499.13 ± 104.08 nm length and exhibited a high hyper peroxidase-like activity. Although the solvothermal method effectively makes up for the shortcomings of the limited adaptation range of the hydrothermal method, the solvothermal method is still carried out under high temperature and high pressure, and the cost of using organic solvents is high. At the same time, the toxicity and danger of organic solvents are difficult to be ignored.

2.3. Co-Precipitation Method

Co-precipitation is a method of adding a suitable precipitant to a mixed solution of various constituent ions so that the main salt ions and impurity ions can be co-precipitated to obtain a precipitated mixture [64]. The main advantages of this method are simplicity of operation, high yield and short reaction time, and more importantly, the relative safety of the preparation process, as it does not require a high-pressure reaction environment [65,66]. Amini et al. used a co-precipitation method by adding a mixed solution of NaOH and K3Fe(CN)6 to a mixed solution of Ni (NO3)2·6H2O and Al (NO3)3·9H2O under nitrogen protection, and then adjusting the pH to 9.6 and reacting at 90 °C for 24 h to obtain Ni/Al-Fe(CN)6 LDH. The nanozyme possesses peroxidase-like activity and can be used to determine chromium in water [52]. In another study, Fe3(PO4)2·8H2O-CDs were synthesised via the co-precipitation method by adding Na3PO4 to a suspension containing CDs, FeSO4, and PVP, and further folic acid modification gave peroxidase-like activity Fe3(PO4)2·8H2O-CDs-FA nanoflowers [53].
In addition, the co-precipitation method was used for Fe/CuSn(OH)6 nanozyme [54] and Fe3O4 MNPs [55] nanozyme preparation. Fe/CuSn(OH)6 nanozyme was synthesised with two-step co-precipitation. NH3·H2O solution and Na2SnO3 solution were successively dropped into CuSO4 solution, and the CuSn(OH)6 precipitate was collected by reaction for 30 min. Then, a certain amount of CuSn(OH)6 and FeSO4·7H2O was added to the deionised water in turn. NaBH4 was added dropwise to the above solution under vigorous stirring, and the resulting product was the Fe/CuSn(OH)6 nanozyme. Fe3O4 MNPs nanozymes were prepared with a high-gravity co-precipitation method. Briefly, a mixture of FeCl3 and FeCl2 with a molar ratio of Fe2+ and Fe3+ of 1:2 and NaOH were pumped into a rotating packed bed from two inlets, respectively. Different high-gravity levels were achieved by controlling the rotation rate, and then Fe3O4 MNPs nanozymes were generated by reacting violently under high-gravity conditions. The biggest advantage of the co-precipitation method is that it requires fewer reaction conditions. However, the method still has the problems of being difficult to control the homogeneity of the composition, producing an easy agglomeration phenomenon, and having a low crystallinity of the product.

3. Iron-Based Nanozymes in Pollutant Degradation

The global economy has been developing rapidly in recent years, and urbanisation and people’s living standards have increased. The large, centralised discharge of urban pollutants and frequent industrial production have led to severe water pollution problems. Iron-based nanozymes are regarded as efficient catalysts for pollutant degradation due to their excellent biocompatibility, efficient pollutant degradation efficiency, milder working environment, and high stability [67]. Pollutant removal is one of the new directions in the application of iron-based nanozymes in the aqueous environment, which mainly utilises the active substances produced by nanozymes to degrade pollutants. In the existing studies, different kinds of iron-based nanozymes can catalyse a variety of substrates, such as dissolved oxygen, hydrogen peroxide, permonosulfate (PMS), and perdisulfate (PS) to produce active substances with strong oxidative properties, such as hydroxyl radicals, superoxide radicals, sulphate radicals, and singlet oxygen, which are effective in degrading pollutants such as dyes, phenolics pollutants, and antibiotics.
Water 16 03431 g002
Figure 2. Pollutant degradation mechanism diagram of (a) FeCu-NC nanozyme [68], (b) Fe3O4@N-HollCS nanozyme [69], (c) FeMn/N-CNTs nanozyme [70], and (d) Fe3O4@CeO2/Tb-MOF nanozyme [71].
Figure 2. Pollutant degradation mechanism diagram of (a) FeCu-NC nanozyme [68], (b) Fe3O4@N-HollCS nanozyme [69], (c) FeMn/N-CNTs nanozyme [70], and (d) Fe3O4@CeO2/Tb-MOF nanozyme [71].
Water 16 03431 g002

3.1. Dye Degradation

Dyes are highly resistant to degradation and pose a risk of carcinogenicity, teratogenicity, and mutagenicity, and their presence in large quantities in water can lead to serious health problems in living organisms [72]. Furthermore, the pigments in the dyes will not only affect the aesthetics of the water body but will also make it less translucent. This will lead to a decrease in the dissolved oxygen content of the water body and a slowdown in the rate of photosynthesis, thus increasing the risk of black odour in the water body [73]. Nevertheless, conventional dye treatment means such as filtration, coagulation, and adsorption are challenging to meet the increasing wastewater treatment standards. Therefore, efficient dye degradation strategies based on nanozymes have attracted much attention. Jain and his associates, prepared an Fe3O4 nanorod with peroxidase-like activity [74]. In the presence of H2O2, the material showed degradation performance for pollutants such as rhodamine B, methylene blue, and methyl orange with removal rates of 98%, 77%, and 60% degradation, respectively. In addition, Wu et al. anchored the Fe-N-C single-atom nanozyme on a nitrogen-doped carbon substrate. The three-dimensional hierarchical ordered multi-hollow structure of the nitrogen-doped carbon substrate endowed the nanozyme with stronger catalytic activity, and the excellent peroxidase activity based on this material could catalyse the production of •OH from H2O2 for rhodamine B degradation [75]. In another similar study, a single-atom nanozyme with lamellar stacked Fe/Cu dual active sites was reported to activate PMS to produce SO4−•, •OH, 1O2, and •O2−, among other active substances, and degraded 99% of rhodamine B within 10 min [76]. Similarly, Chen and his colleagues successfully prepared Co3O4@Co-Fe-oxidised double-shell nanocages (DSNCs) by anion exchange combined with low-temperature pyrolysis using ZIF67 as a starting template [77]. The material possessed excellent peroxidase-like activity and weak oxidase-like activity. It could catalyse the degradation of multiple dye contaminants by PMS, with the degradation rates of acidic magenta, methylene blue, and rhodamine B being 99.1%, 97.0%, and 98.4%, respectively, under the optimised conditions. Remarkably, the material maintained good catalytic activity after 10 cycles. Compared with catalytic H2O2, catalytic PMS appeared more capable of dye degradation, which may be attributed to the ability to catalyse PMS to produce SO4−• with higher oxidative capacity.
In order to further enhance the removal efficiency of dyes, Wang et al. proposed a dual active site strategy using covalent bonding to connect Ag with Fe3O4 nanoparticles. They prepared Ag-Fe3O4 nanozymes with peroxidase-like catalytic activity, which were used in the degradation of dyes [78]. This nanozyme has dual active sites of iron and silver, which can effectively accelerate the decomposition of hydrogen peroxide and generate •OH and •O2− radicals to attack the dye molecules. Notably, the removal rates of ethyl violet, malachite green, and basic magenta under the Ag-Fe3O4/H2O2 system were greater than 97%. However, the removal rates of methylene blue and rhodamine B were less than 50%, implying that the nanozyme has high degradation efficiency and specificity for triarylmethane dyes. In addition, based on the physical properties of Fe3O4, the Ag-Fe3O4 nanozyme could be magnetically separated from the dye solution after the reaction by applying a strong external magnetic field, and the catalytic activity of the Ag-Fe3O4 nanozyme remained unchanged significantly after repeating the reaction for 10 times. Constructing a multi-enzyme system is also an effective method to improve dye degradation efficiency. Jangi et al. constructed a new multi-enzyme system by mixing MnO2 nanozyme and SiO2@Fe3O4 nanozyme in a certain ratio and used it for the degradation of malachite green [79]. In this system, 99.5% of malachite green could be degraded in 5 min, and the degradation rate did not change significantly after ten times reuse.

3.2. Antibiotics Degradation

The widespread and irrational use of antibiotics has caused significant impacts on the ecosystem, and if left unchecked, will lead to the emergence and spread of antibiotic-resistant bacteria and genes [80]. Therefore, it is important to develop efficient, stable and environmentally friendly means of antibiotic removal. Geng et al. prepared an iron-based nanozyme with broad-spectrum degradation of fluoroquinolone antibiotics, and it was shown that the nanozyme could remove fluoroquinolone antibiotics in different aqueous environments, and that •OH plays an essential role in the degradation of antibiotics [81]. Most of the reported single-atom nanozymes are three-dimensional, and the three-dimensional structure somewhat reduces the exposure of the active site of the nanozyme. To solve this problem, Wang et al. synthesised two-dimensional structured iron monoatomic nanozymes with Fe-N coordination numbers of 2, 3, and 4, respectively, under the guidance of theoretical calculations [82]. The experimental results showed that FeSA-N3 with coordination number 3 was the most effective, and the efficient electron transfer reduced the free energy required for the generation of the active substance. The nanozyme exhibited excellent peroxidase activity, high electron transfer efficiency and stability, and could efficiently activate H2O2 to degrade five cephalosporin antibiotics, including cefaclor, 7-aminocephalosporanic acid, cefradine, cefalexin, and cefprozil. In addition, this study combined iron-based nanozymes with ceramic membranes to achieve continuous and stable removal of antibiotics. Notably, the iron-leaching level was maintained very low, demonstrating the environmental friendliness of iron-based nanozymes. Based on the excellent peroxidase-like activity of iron atoms, this study achieved the selective removal of antibiotics by utilising its highly efficient active site and tuneable coordination structure, revealing the influence of the local coordination environment of Fe-N on the catalytic performance of nanozymes, and providing a new perspective for the application of iron-based nanozymes in the field of antibiotic degradation. It should be noted that in the conventional peroxide activation by nanozymes, free radicals or singlet oxygen are the active substances that play a major role. In contrast, Zhang et al. proposed an electron-transfer mode for cycling Fe(III) and Fe(IV)=O intermediates. They suggested that Fe(IV)=O is the key oxidative species for the degradation of pollutants by nanozyme-activated PMS [83]. In this study, an iron single-atom nanozyme with an Fe-N coordination number of 5 was prepared by mimicking cytochrome P450 and used to activate PMS to degrade sulfamethoxazole. The experimental results showed that sulfamethoxazole was completely degraded within 5 min. The oxidation rate was 254 times higher than that of PMS, and the nanozyme demonstrated an excellent pollutant degradation ability. Although some promising progress has been made in single-atom nanozymes, their catalytic activity is still some distance away from that of natural enzymes. Increasing the number of active sites or exposing more active sites is considered one of the ideal solutions to improve the activity of nanozyme [84]. For example, FeCu-NC bimetallic single-atom nanozyme with a three-dimensional porous structure was used to activate PMS, which in turn generated sulphate radicals, hydroxyl radicals, superoxide radicals, and singlet oxygen, among other actives, to efficiently degrade levofloxacin, with a degradation rate of 90.4% for 30 min of the reaction (Figure 2a) [68]. In another study, Zheng and his team provided a nitrogen-doped hollow porous carbon sphere carrier for Fe3O4 to obtain a more active nanozyme [69]. The results showed that the carrier effectively improved the interfacial catalytic ability of Fe3O4, the charge transfer resistance of the composite material was significantly reduced, and the electrons could be easily transferred from the N-atoms to Fe3O4. The Fe3O4@N-HollCS nanozyme produced by •OH and •O2− in the presence of 0.5 mol/L H2O2 -can completely degrade norfloxacin in 60 min (Figure 2b).

3.3. Phenolic Pollutants Degradation

As important raw chemical materials in the pharmaceutical, paper, printing, and dyeing industries, phenols are inevitably entering the water environment despite some wastewater treatment from related industries [85]. Importantly, phenolics pose high carcinogenic and teratogenic risks to humans, so exploring the effective treatment of phenolic compounds has been a focus of research in the water environment field [86]. Iron-based nanozymes have shown good degradation effects on a range of phenolic pollutants, including bisphenol A [70], p-chlorophenol [87], hydroquinone [86,88], and phenol [48].
For example, Lv et al. prepared a single-atom nanozyme FeMn/N-CNTs with a bimetallic active centre, which achieved complete degradation in only 20 min in removal experiments with BPA as the target pollutant [70]. The excellent catalytic activity of FeMn/N-CNTs can be attributed to the following points: (1) the full utilisation of the synergistic effect between the bimetals, where the Mn-N4 sites are more prone to adsorb negatively charged bisphenol A and the Fe-N4 sites are more prone to adsorb H2O2 and generate •OH; (2) the electron cycling process promotes the regeneration of Fe2+ (Figure 2c); and (3) the high charge transfer efficiency. Bimetallic nanozymes are regarded as very promising materials in pollutant degradation. The detailed discussion of the substrate adsorption process and electron transfer mechanism in this study contributes to our in-depth understanding of the promotional effect of bimetallic sites on the activity of nanozymes. In addition, the team has also addressed the role of zero-valent iron in the degradation of p-chlorophenol by bimetallic nanozymes in another published study [87]. Similar to the reasons described in the previous Section, Fe0 generates Fe2+ during oxidation, and Fe0 can react with Fe3+ to generate Fe2+, which rapidly replenishes the Fe2+ consumed by the Fenton reaction. Secondly, the excellent reducing ability of Fe0 can avoid the ineffective decomposition of H2O2. Overall, the nanozyme showed a high degradation ability for simulated and real plant wastewater containing various phenolic pollutants. Liu et al. also prepared a bimetallic nanozyme (FeMn-N), which could remove up to 92% of hydroquinone under optimal reaction conditions [88]. Magnetic nanozymes have also been favoured in phenolic pollutant degradation due to their essential feature of easy recycling. Liao et al. prepared a magnetic Fe3O4 @CeO2/Tb-MOF nanozyme with peroxidase-like activity to degrade natural polyphenol caffeic acid [71]. The experimental results showed that more than 90% of caffeic acid was degraded in the Fe3O4@CeO2/Tb-MOF and H2O2 system within 70 min. The efficient degradation of caffeic acid was attributed to the large number of active substances produced by the synergistic catalysis of Fe3O4 and CeO2 (Figure 2d).

4. Iron-Based Nanozymes in Pollutant Detection

Pollutant detection is one of the main directions of nanozyme applications in the aqueous environment, and the related research accounts for more than 50% of the aqueous environmental applications of nanozymes. The outstanding features of nanozymes, such as low cost, high stability, high catalytic activity, easy modification, and the ability to withstand harsh conditions for a long period, make them particularly suitable for pollutant detection systems. Currently, the application of nanozymes in pollutant detection is mainly based on its peroxidase activity, which undergoes reactions such as colour development, fluorescence, and chemiluminescence to achieve the identification of pollutants. Pollutant detection technology based on nanozymes can effectively detect heavy metals, pesticides, antibiotics, and other toxic and harmful substances in the water environment. Compared with traditional pollutant detection, it has the advantages of a lower technical threshold, convenient on-site deployment, and lower use cost.

4.1. Toxic Ion Detection

Toxic ions are very important industrial materials with strong mobility, solubility, and bioaccumulation, and their release in large quantities poses a serious threat to the safety of the water environment. Most toxic ions are not biodegradable. Several iron-based nanozymes for toxic ion detection have been successfully developed so far. Detecting toxic ions by nanozymes relies on the direct or indirect interaction of toxic ions with the nanozymes, resulting in a change in the catalytic activity of the nanozymes [89]. Yi et al. prepared a CuFe2O4/rGO nanozyme with excellent peroxidase-like activity and established a colorimetric method for the determination of the heavy metal Cr3+ using the inhibition of Cr3+ on the TMB colour development reaction [90]. In the CuFe2O4/rGO-TMB-H2O2 system, the absorbance at 652 nm decreased gradually with increased Cr3+ concentration, and a linear regression equation was established according to this pattern. Under the optimal experimental conditions, CuFe2O4/rGO can achieve colorimetric detection of Cr3+ in the range of 0.1 mM to 25 mM, with a detection limit of 35 nM. Although the CuFe2O4/rGO nanozyme exhibited a certain selectivity for the detection of Cr3+, and more than ten heavy metal ions, including Al3+, Mn2+, Ca2+, and Na+, interfered negligibly in the detection of Cr3+, Cr6+ interfered with the detection of Cr3+ more significantly. However, in real wastewater, Cr6+ and Cr3+ usually co-exist, and therefore the assay still needs to be further developed before it can be useful in real wastewater applications.
Different from the above detection mechanism, Lou et al. first introduced glutathione into the nanozyme (NH2-MIL-101(Fe)@Cu/CeO2)-TMB-H2O2 system to inhibit the oxidation of TMB, and the solution was colourless. When Hg2+ was added to the system, it complexed with the thiol group of glutathione to form GSH-Hg2+, and the solution returned to a blue colour (Figure 3a). Based on the above principles, a colorimetric sensor for detecting Hg2+ was constructed with a detection range of 0.01–4 μM and a detection limit of 0.7 nm. In addition, the team found that Cu2+ was able to interact with NH2-MIL-101(Fe)@Cu/CeO2 surface amino groups, which resulted in a decrease in fluorescence intensity. Based on this, a fluorescence detection method for Cu2+ was developed to achieve sensitive detection of Cu2+ in the range of 8–600 µM [91].
Chen and his team constructed a single-atom nanozyme based on Fe/Cu dual active sites to establish a colorimetric detection method for S2− by taking advantage of the inhibitory effect of S2− on the TMB chromogenic reaction [76]. The method was characterised by high selectivity and sensitivity and could efficiently detect S2− in the range of 0.09–6 μmol/L with a detection limit of 30 nmol/L. In comparison, the Ag-Fe3O4 nanozyme prepared by Wang et al. was capable of detecting S2− in a wider range of linear ranges (10–100 μM), but the detection limit was only 0.4 μM [78].

4.2. Antibiotic Detection

In recent years, various antibiotics have been widely detected in rivers worldwide. The widespread and irrational use of antibiotics has caused significant impacts on the ecological environment. Convenient and rapid detection methods are important for antibiotic pollution control and water quality risk warning. To enable on-site analytical detection of kanamycin, Chen and his colleagues designed a smartphone-capable hydrogel colorimetric platform based on an Fe/CeO2 HBs nanozyme with peroxidase-like activity [93]. Kanamycin covers the active site on the surface of the Fe/CeO2 HBs nanozyme, hindering the oxidation of TMB, which in turn affects the solution colour. Then, the RGB parameters were identified by taking pictures with a smartphone, and the linear relationship between the RGB parameters and kanamycin concentration was used to achieve the on-site detection of kanamycin.
However, there are significant differences between different classes of antibiotics in terms of biotoxicity, environmental chemical behaviour, means of detection, and means of removal. More importantly, enhanced toxicity may occur when multiple antibiotics co-exist. Currently, single-target antibiotic detection methods are inefficient and susceptible to interference from the same type of antibiotic. To address this issue, Che et al. first prepared g-C3N4 with different fluorescence properties and peroxidase activities [94]. Then, the enzyme-like activity of g-C3N4 and the difference in response signals to different antibiotics were enhanced by in situ growth of MIL-101 (Fe) on g-C3N4. A simultaneous detection method for multiple antibiotics was constructed using the signal cross response between different fluorescence channels of g-C3N4/MIL-101(Fe) and antibiotics. The simultaneous detection of multiple antibiotics such as furans, quinolones, lincosamides, and tetracyclines was achieved.

4.3. Pesticide Detection

Pesticides are one of the most important tools in modern pesticide production and can effectively improve the quality of agricultural products [95]. However, a growing number of studies have confirmed that pesticide exposure has significant adverse effects on human health, including cancer, reproductive diseases, and metabolic disorders [96]. Iron-based nanozymes have also shown some potential in the field of pesticide detection. Liu et al. combined the peroxidase-like activity of iron-based nanozymes with the principle of photoluminescence to construct a carbaryl detection based on the interaction relationship between iron-based nanozymes, H2O2, o-phenylenediamine, acetylcholine lipase, and acetylthiocholine chloride [92]. The principles utilised in this assay can be summarised in the following three points (Figure 3b). (1) NH2-MIL-101 (Fe) is capable of fluorescing at 428 nm, and when in the presence of H2O2, it is capable of oxidising o-phenylenediamine to diaminophenazine, which produces a significant fluorescence at 556 nm; the fluorescence at 556 nm inhibits the intrinsic fluorescence signals of iron-based nanozymes. (2) Acetylthiocholine Lipase Catalytic hydrolysis of acetylthiocholine chloride produces thiocholine that inhibits the oxidation of o-phenylenediamine, resulting in a decrease in the fluorescence signal at 556 nm and a recovery of the fluorescence signal at 428 nm. (3) Inactivation of acetylcholine lipase in the presence of carbaryl enhances the fluorescence model at 556 nm. Similarly, Xu et al. introduced a nitro functional group into an iron-based organometallic framework (MIL-101(Fe)) and synthesised a nanozyme (NO2-MIL-101) with an active site structure similar to that of the natural enzyme and with excellent peroxidase-like activity [97]. The nanozyme was successfully applied to the concentration assay of paraoxon-ethyl. Similar to the principle utilised by Liu et al., this study also used the effect of organophosphorus pesticides on acetylcholine lipase activity as the entry point for the assay. The difference is that Liu et al.‘s study was based on changes in the fluorescent signal, whereas Xu et al. relied on the colour development reaction of TMB. Both methods showed certain advantages in terms of sensitivity and anti-interference ability, but the detection process usually relies on experimental instruments such as spectrophotometers, which still have the problems of complicated operation and more reagents required, making it difficult to realise the in situ detection of target pollutants. In order to solve this problem, Zhang et al. designed a colorimetric sensor based on the Fe-N/C single-atom nanozyme using carbon black as a template through the ‘Ligand-mediated’ strategy and combined it with the colour signal analysis of a smartphone. A sensing platform was formed to achieve real-time quantitative monitoring of organophosphorus pesticides in water [98]. The method is based on the inhibitory effect of ascorbic acid produced by acid phosphatase on the TMB colour development reaction. When organophosphorus pesticides are present, the colour development reaction of TMB is inhibited, resulting in obvious colour changes. Then, the efficient detection of organophosphorus pesticides was achieved by acquiring RGB colour information through a smartphone handset and establishing a linear relationship between RGB colour information and organophosphorus pesticide concentration. The detection method of obtaining colour information changes through smartphones is more conducive to the convenient detection of target pollutants.

4.4. Phenolic Pollutants Detection

Phenols are widely used in pharmaceuticals, petrochemical industry, food processing, plastics processing, and pesticide production. Long-term exposure to phenols will have serious effects on the nervous system, immune system, reproductive system, and endocrine system and may even pose a risk of cancer [99,100]. Thus, it is significant to achieve efficient and accurate detection of phenolic pollutants in the aqueous environment. In some representative examples, Zhang et al. constructed a method based on the iron-based nanozymes Au@Fe3O4 for the detection of hydroquinone in the range of 0–30 μM [101]. The method is mainly based on the fact that the strong reducing property of hydroquinone reduces the oxidation products of TMB, causing the solution to change from blue to colourless. In addition, it was found that the change in absorbance was more significant under light conditions, attributed to the hot electrons excited by the surface plasmon resonance effect of the gold nanoparticles that increased the •OH content in the solution. In another study, also taking advantage of the reducing properties of hydroquinone, Chu and colleagues prepared an N-doped graphene nano-sheet-loaded iron single-atom nanozyme (Fe-CNG) with oxidase-like activity for hydroquinone detection [102]. Compared to nanozymes with peroxidase-like activity, nanozymes with oxidase-like activity can detect target pollutants without H2O2, with less dependence on additional reagents. Hou et al. prepared a nanozyme with peroxidase-like activity by assembling a covalent organic framework on magnetic Fe3O4@ZIF-8 nanozyme and used it for the detection of phenol [103]. A specific chromogenic reaction between 4-aminoantipyrine and phenolics present in the presence of H2O2 enables the detection of phenol. In addition, Lin et al. prepared a laccase mimic (Fe1@CN-20) with low metal content for the efficient detection of phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dimethoxyphenol, and catechol [85].

5. Conclusions and Outlooks

The presence of pollutants in the water environment poses a serious threat to the ecological environment and human health and has become a worldwide problem that cannot be ignored. The development of efficient pollutant identification and degradation strategies is one of the effective means to prevent and resolve environmental risks. As a branch in the field of artificial enzymes, iron-based nanozymes have successfully achieved an effective combination of the environmentally friendly and low-cost properties of iron-based nanomaterials with the high catalytic activity of natural enzymes. In recent years, more and more iron-based nanozymes have been reported in the field of aqueous environment, which fully reflects the attention of scholars to this field and implies that iron-based nanozymes have great opportunities in the field of aqueous environment. The excellent catalytic properties of iron-based nanozymes may have broad application prospects in the future in combating membrane pollution, removing hard-to-biodegrade pollutants, and combating cyanobacterial blooms. In addition, the unique colour development, fluorescence, and chemiluminescence reactions of iron-based nanozymes can help them make significant progress in the in situ detection of pollutants and the development of rapid test papers.
Despite the great strides made in both the development and application of iron-based nanozymes, there are still many gaps to be filled. In order to achieve high-quality development of iron-based nanozymes in the field of water environment, more efforts are needed in the following areas:
  • Attention should be paid to pollutant degradation mechanisms other than free radicals. The current discussion on the mechanism of pollutant degradation by iron-based nanozymes mainly focuses on free radicals. However, other factors may also play an important role in the pollutant degradation process, such as the adsorption and diffusion process on the surface of nanozymes, functional groups on the surface of nanozymes, and the structure of the surface of nanozymes. It is suggested that the discussion on the above should be strengthened in the Section on removal mechanisms.
  • The toxicity of iron-based nanozymes should be more comprehensively assessed. The current study is lacking in analysing the potential environmental toxicity of iron-based nanozymes. It is recommended that long-term exposure experiments be carried out for the specific application scenario of the aqueous environment to study the toxic effects of iron-based nanozymes on organisms and to understand the long-term effects on their growth, reproduction, behaviour, and physiological functions, for example, to observe the effects of nanozymes on the growth and development, reproductive capacity, and immune system of related indicator organisms, such as Chlorella and fish. In addition, the development of low-toxicity nanozymes is necessary to improve the environmental compatibility of iron-based nanozymes by a range of means, including surface physicochemical property tuning and immobilisation strategies.
  • Combined processes for pollutant treatment based on iron-based nanozymes need to be enriched. Current iron-based nanozymes are mostly used for pollutant degradation in the form of a single powder. However, many functions of these nanozymes remain unexplored, and the real water environment is complex and diverse, which is difficult for a single treatment process to cope with. Therefore, there is an urgent need to develop novel nanozyme combination processes for pollutant degradation.
  • The influence of key parameters in typical preparation processes on the performance of iron-based nanozymes needs to be explored. So far, scholars have extensively applied iron-based nanozymes to pollutant degradation and detection. However, less attention has been paid to the effects of preparation processes, such as reaction temperature, stirring time, and reagent ratios, on the pollutant degradation and detection ability of iron-based nanozymes, and the potential mechanisms of iron-based nanozymes’ sizes, structures, and other physicochemical properties on the pollutant degradation and detection have not been fully understood.

Author Contributions

X.C.: investigation, data analysis, validation, writing—original draft. G.F.: investigation, data analysis, validation, writing—original draft, writing—review and editing, funding acquisition. S.W.: data analysis, validation, writing—original draft. J.L., Y.L., W.Z., S.M. and K.-Q.X.: validation, writing—review and editing. All authors have read and agreed to the published version of the manuscript.

Funding

This work was financially supported by the Natural Science Foundation of Fujian Province in China (No. 2023J02006, No. 2021N0022, No. 2021Y3002), the Science and Technology Project of Fuzhou City (No. 2022-P-013), and the Science and Technology Project of Anhui Province (No. 2021-YF26, No. 2021-YF27).

Data Availability Statement

No new data were created or analysed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

Author Jing Luo was employed by the company Fujian Jinhuang Environmental Sci-Tech Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Sukatis, F.F.; Wee, S.Y.; Aris, A.Z. Potential of biocompatible calcium-based metal-organic frameworks for the removal of endocrine-disrupting compounds in aqueous environments. Water Res. 2022, 218, 118406. [Google Scholar] [CrossRef]
  2. Li, D.; Zhang, S.; Li, S.; Tang, J.; Hua, T.; Li, F. Mechanism of the application of single-atom catalyst-activated PMS/PDS to the degradation of organic pollutants in water environment: A review. J. Clean. Prod. 2023, 397, 136468. [Google Scholar] [CrossRef]
  3. Shaheen, S.M.; Natasha; Mosa, A.; El-Naggar, A.; Hossain, F.; Abdelrahman, H.; Niazi, N.K.; Shahid, M.; Zhang, T.; Tsang, Y.F.; et al. Manganese oxide-modified biochar: Production, characterization and applications for the removal of pollutants from aqueous environments—A review. Bioresour. Technol. 2022, 346, 126581. [Google Scholar] [CrossRef] [PubMed]
  4. Chakraborty, U.; Kaur, G.; Rubahn, H.-G.; Kaushik, A.; Chaudhary, G.R.; Mishra, Y.K. Advanced metal oxides nanostructures to recognize and eradicate water pollutants. Prog. Mater. Sci. 2023, 139, 101169. [Google Scholar] [CrossRef]
  5. Wee, S.Y.; Aris, A.Z. Endocrine disrupting compounds in drinking water supply system and human health risk implication. Environ. Int. 2017, 106, 207–233. [Google Scholar] [CrossRef]
  6. Ning, R.; Yu, S.; Li, L.; Snyder, S.A.; Li, P.; Liu, Y.; Togbah, C.F.; Gao, N. Micro and nanobubbles-assisted advanced oxidation processes for water decontamination: The importance of interface reactions. Water Res. 2024, 265, 122295. [Google Scholar] [CrossRef]
  7. Yue, T.; Cao, X.; Liu, Q.; Bai, S.; Zhang, F.; Liu, L. Enhancement on removal of oxytetracycline in aqueous solution by corn stover biochar: Comparison of KOH and KMnO4 modifications. Chem. Eng. Res. Des. 2023, 190, 353–365. [Google Scholar] [CrossRef]
  8. Ren, H.; Qian, H.; Hou, Q.; Li, W.; Ju, M. Removal of ionic liquid in water environment: A review of fundamentals and applications. Sep. Purif. Technol. 2023, 310, 123112. [Google Scholar] [CrossRef]
  9. Zhou, T.; Zhang, Z.; Liu, H.; Dong, S.; Nghiem, L.D.; Gao, L.; Chaves, A.V.; Zamyadi, A.; Li, X.; Wang, Q. A review on microalgae-mediated biotechnology for removing pharmaceutical contaminants in aqueous environments: Occurrence, fate, and removal mechanism. J. Hazard. Mater. 2023, 443, 130213. [Google Scholar] [CrossRef] [PubMed]
  10. Patel, M.; Kumar, R.; Kishor, K.; Mlsna, T.; Pittman, C.U., Jr.; Mohan, D. Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods. Chem. Rev. 2019, 119, 3510–3673. [Google Scholar] [CrossRef]
  11. Fan, G.; Lin, C.; You, W.; Song, Y.; Cao, X.; Luo, J.; Zou, J.; Hong, Z.; Xu, K.-Q. Cow manure biochar for activation of peroxymonosulfate to degrade 17β-estradiol: Performance and mechanism. J. Mol. Liq. 2024, 408, 125427. [Google Scholar] [CrossRef]
  12. Matamoros, V.; Gutiérrez, R.; Ferrer, I.; García, J.; Bayona, J.M. Capability of microalgae-based wastewater treatment systems to remove emerging organic contaminants: A pilot-scale study. J. Hazard. Mater. 2015, 288, 34–42. [Google Scholar] [CrossRef] [PubMed]
  13. Liu, L.; Yu, R.; Zhao, S.; Cao, X.; Zhang, X.; Bai, S. Heterogeneous Fenton system driven by iron-loaded sludge biochar for sulfamethoxazole-containing wastewater treatment. J. Environ. Manag. 2023, 335, 117576. [Google Scholar] [CrossRef] [PubMed]
  14. Cao, X.; Fan, G.; Luo, J.; Zhang, L.; Wu, S.; Yao, Y.; Xu, K.-Q. High-efficiency removal of microcystis aeruginosa using Z-scheme AgBr/NH2-MIL-125(Ti) photocatalyst with superior visible-light absorption: Performance insights and mechanisms. J. Hazard. Mater. 2024, 478, 135461. [Google Scholar] [CrossRef] [PubMed]
  15. Shamsipur, M.; Yazdanfar, N.; Ghambarian, M. Combination of solid-phase extraction with dispersive liquid–liquid microextraction followed by GC–MS for determination of pesticide residues from water, milk, honey and fruit juice. Food Chem. 2016, 204, 289–297. [Google Scholar] [CrossRef]
  16. Salcedo, G.M.; Kupski, L.; Degang, L.; Marube, L.C.; Caldas, S.S.; Primel, E.G. Determination of fifteen phenols in wastewater from petroleum refinery samples using a dispersive liquid—Liquid microextraction and liquid chromatography with a photodiode array detector. Microchem. J. 2019, 146, 722–728. [Google Scholar] [CrossRef]
  17. Fang, J.; Zhao, H.; Zhang, Y.; Lu, M.; Cai, Z. Atmospheric pressure chemical ionization in gas chromatography-mass spectrometry for the analysis of persistent organic pollutants. Trends Environ. Anal. Chem. 2020, 25, e00076. [Google Scholar] [CrossRef]
  18. Wang, Q.; Hou, Y.; Lin, M.; Yang, Q. Construction of extracellular peptide laccase-mimic nanozyme for the detection and degradation of phenols pollutants. Colloids Surfaces A Physicochem. Eng. Asp. 2024, 699, 134687. [Google Scholar] [CrossRef]
  19. Qi, J.; Li, B.; Wang, X.; Fu, L.; Luo, L.; Chen, L. Rotational Paper-Based Microfluidic-Chip Device for Multiplexed and Simultaneous Fluorescence Detection of Phenolic Pollutants Based on a Molecular-Imprinting Technique. Anal. Chem. 2018, 90, 11827–11834. [Google Scholar] [CrossRef]
  20. Gu, C.; Su, X.; Liu, B.; Zheng, C.; Wang, S.; Tian, Y.; Ma, J.; Wu, L. Recent progress in advanced materials for electrochemical determination of phenolic contaminants. Microchem. J. 2023, 195, 109513. [Google Scholar] [CrossRef]
  21. Wang, K.; Meng, X.; Yan, X.; Fan, K. Nanozyme-based point-of-care testing: Revolutionizing environmental pollutant detection with high efficiency and low cost. Nano Today 2024, 54, 102145. [Google Scholar] [CrossRef]
  22. Shen, Y.; Wei, Y.; Gao, X.; Nie, C.; Wang, J.; Wu, Y. Engineering an Enzymatic Cascade Catalytic Smartphone-Based Sensor for Onsite Visual Ratiometric Fluorescence–Colorimetric Dual-Mode Detection of Methyl Mercaptan. Environ. Sci. Technol. 2023, 57, 1680–1691. [Google Scholar] [CrossRef] [PubMed]
  23. Unnikrishnan, B.; Lien, C.-W.; Chu, H.-W.; Huang, C.-C. A review on metal nanozyme-based sensing of heavy metal ions: Challenges and future perspectives. J. Hazard. Mater. 2021, 401, 123397. [Google Scholar] [CrossRef]
  24. Winkler, M.; Geier, M.; Hanlon, S.P.; Nidetzky, B.; Glieder, A. Human Enzymes for Organic Synthesis. Angew. Chem. Int. Ed. 2018, 57, 13406–13423. [Google Scholar] [CrossRef] [PubMed]
  25. Kalaiarasan, E.; Palvannan, T. Removal of phenols from acidic environment by horseradish peroxidase (HRP): Aqueous thermostabilization of HRP by polysaccharide additives. J. Taiwan Inst. Chem. Eng. 2014, 45, 625–634. [Google Scholar] [CrossRef]
  26. Guan, Z.-B.; Luo, Q.; Wang, H.-R.; Chen, Y.; Liao, X.-R. Bacterial laccases: Promising biological green tools for industrial applications. Cell. Mol. Life Sci. 2018, 75, 3569–3592. [Google Scholar] [CrossRef] [PubMed]
  27. Reetz, M.T. What are the Limitations of Enzymes in Synthetic Organic Chemistry? Chem. Rec. 2016, 16, 2449–2459. [Google Scholar] [CrossRef]
  28. Osete-Alcaraz, A.; Bautista-Ortín, A.B.; Ortega-Regules, A.E.; Gómez-Plaza, E. Combined Use of Pectolytic Enzymes and Ultrasounds for Improving the Extraction of Phenolic Compounds During Vinification. Food Bioprocess Technol. 2019, 12, 1330–1339. [Google Scholar] [CrossRef]
  29. Zandieh, M.; Liu, J. Nanozymes: Definition, Activity, and Mechanisms. Adv. Mater. 2024, 36, e2211041. [Google Scholar] [CrossRef]
  30. Tang, G.; He, J.; Liu, J.; Yan, X.; Fan, K. Nanozyme for tumor therapy: Surface modification matters. Exploration 2021, 1, 75–89. [Google Scholar] [CrossRef]
  31. Wu, Y.; Xu, W.; Jiao, L.; Tang, Y.; Chen, Y.; Gu, W.; Zhu, C. Defect engineering in nanozymes. Mater. Today 2022, 52, 327–347. [Google Scholar] [CrossRef]
  32. Gao, L.; Zhuang, J.; Nie, L.; Zhang, J.; Zhang, Y.; Gu, N.; Wang, T.; Feng, J.; Yang, D.; Perrett, S.; et al. Intrinsic peroxidase-like activity of ferromagnetic nanoparticles. Nat. Nanotechnol. 2007, 2, 577–583. [Google Scholar] [CrossRef] [PubMed]
  33. Singh, H.; Bamrah, A.; Bhardwaj, S.K.; Deep, A.; Khatri, M.; Brown, R.J.C.; Bhardwaj, N.; Kim, K.-H. Recent advances in the application of noble metal nanoparticles in colorimetric sensors for lead ions. Environ. Sci. Nano 2021, 8, 863–889. [Google Scholar] [CrossRef]
  34. Xu, X.; Wu, S.; Guo, D.; Niu, X. Construction of a recyclable oxidase-mimicking Fe3O4@MnOx-based colorimetric sensor array for quantifying and identifying chlorophenols. Anal. Chim. Acta 2020, 1107, 203–212. [Google Scholar] [CrossRef]
  35. Wang, F.; Chen, L.; Liu, D.; Ma, W.; Dramou, P.; He, H. Nanozymes based on metal-organic frameworks: Construction and prospects. TrAC Trends Anal. Chem. 2020, 133, 116080. [Google Scholar] [CrossRef]
  36. Jouyban, A.; Amini, R. Layered double hydroxides as an efficient nanozyme for analytical applications. Microchem. J. 2021, 164, 105970. [Google Scholar] [CrossRef]
  37. Li, M.; Zhang, H.; Hou, Y.; Wang, X.; Xue, C.; Li, W.; Cai, K.; Zhao, Y.; Luo, Z. State-of-the-art iron-based nanozymes for biocatalytic tumor therapy. Nanoscale Horiz. 2020, 5, 202–217. [Google Scholar] [CrossRef]
  38. Fu, R.; Ma, Z.; Zhao, H.; Jin, H.; Tang, Y.; He, T.; Ding, Y.; Zhang, J.; Ye, D. Research Progress in Iron-Based Nanozymes: Catalytic Mechanisms, Classification, and Biomedical Applications. Anal. Chem. 2023, 95, 10844–10858. [Google Scholar] [CrossRef]
  39. Sutrisno, L.; Hu, Y.; Hou, Y.; Cai, K.; Li, M.; Luo, Z. Progress of Iron-Based Nanozymes for Antitumor Therapy. Front. Chem. 2020, 8, 680. [Google Scholar] [CrossRef] [PubMed]
  40. Shi, C.; Li, Y.; Gu, N. Iron-Based Nanozymes in Disease Diagnosis and Treatment. ChemBioChem 2020, 21, 2722–2732. [Google Scholar] [CrossRef]
  41. Wang, W.; Huang, Z.; Huang, Y.; Pan, X.; Wu, C. Updates on the applications of iron-based nanoplatforms in tumor theranostics. Int. J. Pharm. 2020, 589, 119815. [Google Scholar] [CrossRef] [PubMed]
  42. Ghazzy, A.; Nsairat, H.; Said, R.; Sibai, O.A.; AbuRuman, A.; Shraim, A.S.; Al Hunaiti, A. Magnetic iron oxide-based nanozymes: From synthesis to application. Nanoscale Adv. 2024, 6, 1611–1642. [Google Scholar] [CrossRef] [PubMed]
  43. Hu, Z.; Mahdi, E.M.; Peng, Y.; Qian, Y.; Zhang, B.; Yan, N.; Yuan, D.; Tan, J.-C.; Zhao, D. Kinetically controlled synthesis of two-dimensional Zr/Hf metal–organic framework nanosheets via a modulated hydrothermal approach. J. Mater. Chem. A 2017, 5, 8954–8963. [Google Scholar] [CrossRef]
  44. Lin, L.; Chen, D.; Lu, C.; Wang, X. Fluorescence and colorimetric dual-signal determination of Fe3+ and glutathione with MoSe2@Fe nanozyme. Microchem. J. 2022, 177, 107283. [Google Scholar] [CrossRef]
  45. Feng, L.; Zhang, L.; Chu, S.; Zhang, S.; Chen, X.; Du, Z.; Gong, Y.; Wang, H. Controllable doping of Fe atoms into MoS2 nanosheets towards peroxidase-like nanozyme with enhanced catalysis for colorimetric analysis of glucose. Appl. Surf. Sci. 2022, 583, 152496. [Google Scholar] [CrossRef]
  46. Ahmad, H.A.; Hassan, R.O. Newly synthesized Fe-doped CDs for colorimetric and fluorometric nanozyme-based levodopa sensing. Luminescence 2023, 38, 437–449. [Google Scholar] [CrossRef] [PubMed]
  47. Xu, S.; Zhang, S.; Li, Y.; Liu, J. Facile Synthesis of Iron and Nitrogen Co-Doped Carbon Dot Nanozyme as Highly Efficient Peroxidase Mimics for Visualized Detection of Metabolites. Molecules 2023, 28, 6064. [Google Scholar] [CrossRef] [PubMed]
  48. Jiang, J.; He, C.; Wang, S.; Jiang, H.; Li, J.; Li, L. Recyclable ferromagnetic chitosan nanozyme for decomposing phenol. Carbohydr. Polym. 2018, 198, 348–353. [Google Scholar] [CrossRef]
  49. He, N.; Zhu, X.; Liu, F.; Yu, R.; Xue, Z.; Liu, X. Rational design of FeS2-encapsulated covalent organic frameworks as stable and reusable nanozyme for dual-signal detection glutathione in cell lysates. Chem. Eng. J. 2022, 445, 136543. [Google Scholar] [CrossRef]
  50. Huang, Y.; Ding, Z.; Li, Y.; Xi, F.; Liu, J. Magnetic Nanozyme Based on Loading Nitrogen-Doped Carbon Dots on Mesoporous Fe3O4 Nanoparticles for the Colorimetric Detection of Glucose. Molecules 2023, 28, 4573. [Google Scholar] [CrossRef]
  51. Sun, M.; Pu, K.; Hao, X.; Liu, T.; Lu, Z.; Su, G.; Wu, C.; Wang, Y.; Cai, S.; Zhao, X.; et al. Reasonable construction of a bimetallic organic framework MIL-88B (Fe, Ni) nanoenzyme based on deep learning assisted doxycycline hydrochloride and methyloxytetracycline hydrochloride. J. Mater. Chem. C 2024, 12, 221–231. [Google Scholar] [CrossRef]
  52. Amini, R.; Rahimpour, E.; Jouyban, A. An optical sensing platform based on hexacyanoferrate intercalated layered double hydroxide nanozyme for determination of chromium in water. Anal. Chim. Acta 2020, 1117, 9–17. [Google Scholar] [CrossRef] [PubMed]
  53. Guo, J.; Wang, Y.; Zhao, M. Target-directed functionalized ferrous phosphate-carbon dots fluorescent nanostructures as peroxidase mimetics for cancer cell detection and ROS-mediated therapy. Sensors Actuators B Chem. 2019, 297, 126739. [Google Scholar] [CrossRef]
  54. Liu, H.; Ding, Y.-N.; Yang, B.; Liu, Z.; Zhang, X.; Liu, Q. Iron Doped CuSn(OH)6 Microspheres as a Peroxidase-Mimicking Artificial Enzyme for H2O2 Colorimetric Detection. ACS Sustain. Chem. Eng. 2018, 6, 14383–14393. [Google Scholar] [CrossRef]
  55. Xiao, M.; Li, N.; Lv, S. Iron oxide magnetic nanoparticles exhibiting zymolyase-like lytic activity. Chem. Eng. J. 2020, 394, 125000. [Google Scholar] [CrossRef]
  56. Zhang, S.; Geng, W.; He, X.; Tu, J.; Ma, M.; Duan, L.; Zhang, Q. Humidity sensing performance of mesoporous CoO(OH) synthesized via one-pot hydrothermal method. Sensors Actuators B Chem. 2019, 280, 46–53. [Google Scholar] [CrossRef]
  57. Chai, K.; Xu, S. Synthesis and mechanism of a new environment-friendly flame retardant (anhydrous magnesium carbonate) by hydrothermal method. Adv. Powder Technol. 2022, 33, 103776. [Google Scholar] [CrossRef]
  58. Meng, L.-Y.; Wang, B.; Ma, M.-G.; Lin, K.-L. The progress of microwave-assisted hydrothermal method in the synthesis of functional nanomaterials. Mater. Today Chem. 2016, 1–2, 63–83. [Google Scholar] [CrossRef]
  59. Fu, Q.; Wei, C.; Wang, M. Transition-Metal-Based Nanozymes: Synthesis, Mechanisms of Therapeutic Action, and Applications in Cancer Treatment. ACS Nano 2024, 18, 12049–12095. [Google Scholar] [CrossRef]
  60. Kong, J.; Zhou, F. Preparation and Application of Carbon Dots Nanozymes. Antioxidants 2024, 13, 535. [Google Scholar] [CrossRef]
  61. Ono, K.; Kimura, K.; Kato, T.; Hayashi, K.; Rajapakse, R.M.; Shimomura, M. Epitaxial growth of a homogeneous anatase TiO2 thin film on LaAlO3 (0 0 1) using a solvothermal method with anticorrosive ligands. Chem. Eng. J. 2023, 451, 138893. [Google Scholar] [CrossRef]
  62. Li, Y.; Li, C.; Wang, B.; Li, W.; Che, P. A comparative study on the thermoelectric properties of CoSb3 prepared by hydrothermal and solvothermal route. J. Alloy. Compd. 2019, 772, 770–774. [Google Scholar] [CrossRef]
  63. Arora, A.; Oswal, P.; Datta, A.; Kumar, A. Complexes of metals with organotellurium compounds and nanosized metal tellurides for catalysis, electrocatalysis and photocatalysis. Co-ord. Chem. Rev. 2022, 459, 214406. [Google Scholar] [CrossRef]
  64. Lin, S.; Zhang, T. Research progress in preparation and application of spinel-type metallic oxides (M ≥ 2). J. Alloy. Compd. 2023, 962, 171117. [Google Scholar] [CrossRef]
  65. Selvaraj, R.; Pai, S.; Vinayagam, R.; Varadavenkatesan, T.; Kumar, P.S.; Duc, P.A.; Rangasamy, G. A recent update on green synthesized iron and iron oxide nanoparticles for environmental applications. Chemosphere 2022, 308, 136331. [Google Scholar] [CrossRef]
  66. Rangel, W.M.; Santa, R.A.A.B.; Riella, H.G. A facile method for synthesis of nanostructured copper (II) oxide by coprecipitation. J. Mater. Res. Technol. 2020, 9, 994–1004. [Google Scholar] [CrossRef]
  67. Diao, Q.; Chen, X.; Tang, Z.; Li, S.; Tian, Q.; Bu, Z.; Liu, H.; Liu, J.; Niu, X. Nanozymes: Powerful catalytic materials for environmental pollutant detection and degradation. Environ. Sci. Nano 2024, 11, 766–796. [Google Scholar] [CrossRef]
  68. Xie, X.; Zhao, Y.; Fan, Y.; Jiang, L.; Liu, W.; Yang, X. Multifunctional Fe/Cu Dual-Single Atom Nanozymes with Enhanced Peroxidase Activity for Isoniazid Detection and Levofloxacin Degradation. Langmuir 2024, 40, 12671–12680. [Google Scholar] [CrossRef]
  69. Zheng, Y.; Liao, D.; Xie, B.; Sun, J.; Sun, J.; Tong, Z.; Zhou, G. Tuning the heterostructure improves the catalytic activity of recyclable nanozymes for efficient absorption and degradation of norfloxacin-contaminated water. Sep. Purif. Technol. 2024, 338, 126576. [Google Scholar] [CrossRef]
  70. Lv, X.; Shu, A.; Shu, L.; Liu, H.; Liu, Y.; Cui, K.; Tang, Y.; Chen, X. Electron cycling mechanism in Fe/Mn DSAzyme accelerates BPA degradation and nanoenzyme regeneration. J. Hazard. Mater. 2024, 476, 135228. [Google Scholar] [CrossRef]
  71. Liao, X.; Li, B.; Wang, L.; Chen, Y. Boric acid functionalized Fe3O4@CeO2/Tb-MOF as a luminescent nanozyme for fluorescence detection and degradation of caffeic acid. Biosens. Bioelectron. 2024, 264, 116637. [Google Scholar] [CrossRef] [PubMed]
  72. Rathi, B.S.; Kumar, P.S. Sustainable approach on the biodegradation of azo dyes: A short review. Curr. Opin. Green Sustain. Chem. 2022, 33, 100578. [Google Scholar] [CrossRef]
  73. Varjani, S.; Rakholiya, P.; Ng, H.Y.; You, S.; Teixeira, J.A. Microbial degradation of dyes: An overview. Bioresour. Technol. 2020, 314, 123728. [Google Scholar] [CrossRef] [PubMed]
  74. Jain, S.; Panigrahi, A.; Sarma, T.K. Counter Anion-Directed Growth of Iron Oxide Nanorods in a Polyol Medium with Efficient Peroxidase-Mimicking Activity for Degradation of Dyes in Contaminated Water. ACS Omega 2019, 4, 13153–13164. [Google Scholar] [CrossRef] [PubMed]
  75. Wu, S.; Wu, W.; Zhu, X.; Li, M.; Zhao, J.; Dong, S. Atomically dispersed hierarchically ordered porous Fe-N-C single-atom nanozymes for dyes degradation. Nano Res. 2023, 16, 10840–10847. [Google Scholar] [CrossRef]
  76. Chen, X.; Wang, Y.; Feng, M.; Deng, D.; Xie, X.; Deng, C.; Khattak, K.N.; Yang, X. Dual-active-site Fe/Cu single-atom nanozymes with multifunctional specific peroxidase-like properties for S2− detection and dye degradation. Chin. Chem. Lett. 2022, 34, 107969. [Google Scholar] [CrossRef]
  77. Chen, Q.; Zhang, X.; Li, S.; Tan, J.; Xu, C.; Huang, Y. MOF-derived Co3O4@Co-Fe oxide double-shelled nanocages as multi-functional specific peroxidase-like nanozyme catalysts for chemo/biosensing and dye degradation. Chem. Eng. J. 2020, 395, 125130. [Google Scholar] [CrossRef]
  78. Wang, Y.; Ding, Y.; Tan, Y.; Liu, X.; Fu, L.; Qing, W. Ag-Fe3O4 nanozyme with peroxidase-like activity for colorimetric detection of sulfide ions and dye degradation. J. Environ. Chem. Eng. 2023, 11, 109150. [Google Scholar] [CrossRef]
  79. Jangi, S.R.H.; Davoudli, H.K.; Delshad, Y.; Jangi, M.R.H.; Jangi, A.R.H. A novel and reusable multinanozyme system for sensitive and selective quantification of hydrogen peroxide and highly efficient degradation of organic dye. Surf. Interfaces 2020, 21, 100771. [Google Scholar] [CrossRef]
  80. Liu, Q.; Bian, Y.; Xu, T.; Yue, T.; Cao, X.; Bai, S.; Lin, H.; Liu, L. Removal potential and mechanism of sulfamethoxazole and norfloxacin by biochar derived from bagasse and polymeric ferric sulfate. Chem. Eng. Res. Des. 2024, 204, 400–409. [Google Scholar] [CrossRef]
  81. Geng, X.; Song, K.; Hu, Q.; Yin, Y.; Li, H.; Yan, X.; Jiang, B. Broad-spectrum degradation of fluoroquinolone antibiotics by Hemin-His-Fe nanozymes with peroxidase-like activity. J. Mater. Chem. B 2024, 12, 8647–8654. [Google Scholar] [CrossRef] [PubMed]
  82. Wang, J.; Zhang, J.; Guo, K.; Yue, Q.; Yin, K.; Xu, X.; Li, Y.; Gao, Y.; Gao, B. Coordination Number Regulation of Iron Single-Atom Nanozyme for Enhancing H2O2 Activation and Selectively Eliminating Cephalosporin Antibiotics. Adv. Funct. Mater. 2024, 34, 2406790. [Google Scholar] [CrossRef]
  83. Zhang, H.; Cui, P.; Xie, D.; Wang, Y.; Wang, P.; Sheng, G. Axial N Ligand-Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single-Atoms Nanozymes. Adv. Sci. 2023, 10, 2205681. [Google Scholar] [CrossRef] [PubMed]
  84. Xie, X.; Chen, X.; Wang, Y.; Zhang, M.; Fan, Y.; Yang, X. High-loading Cu single-atom nanozymes supported by carbon nitride with peroxidase-like activity for the colorimetric detection of tannic acid. Talanta 2023, 257, 124387. [Google Scholar] [CrossRef]
  85. Lin, Y.; Wang, F.; Yu, J.; Zhang, X.; Lu, G.-P. Iron single-atom anchored N-doped carbon as a ‘laccase-like’ nanozyme for the degradation and detection of phenolic pollutants and adrenaline. J. Hazard. Mater. 2022, 425, 127763. [Google Scholar] [CrossRef]
  86. Zhang, X.; Liu, B.; Wei, T.; Liu, Z.; Li, J. Self-propelled Janus magnetic micromotors as peroxidase-like nanozyme for colorimetric detection and removal of hydroquinone. Environ. Sci. Nano 2023, 10, 476–488. [Google Scholar] [CrossRef]
  87. Lv, X.; Liu, H.; Li, Z.; Cui, M.; Cui, K.; Guo, Z.; Dai, Z.; Wang, B.; Chen, X. Critical role of zero-valent iron in the efficient activation of H2O2 for 4-CP degradation by bimetallic peroxidase-like. Environ. Sci. Pollut. Res. 2024, 31, 10838–10852. [Google Scholar] [CrossRef]
  88. Liu, B.; Wang, Z.; Wei, T.; Liu, Z.; Li, J. Bimetallic FeMn-N nanoparticles as nanocatalyst with dual enzyme-mimic activities for simultaneous colorimetric detection and degradation of hydroquinone. J. Environ. Chem. Eng. 2023, 11, 110186. [Google Scholar] [CrossRef]
  89. Li, X.; Wang, L.; Du, D.; Ni, L.; Pan, J.; Niu, X. Emerging applications of nanozymes in environmental analysis: Opportunities and trends. TrAC Trends Anal. Chem. 2019, 120, 115653. [Google Scholar] [CrossRef]
  90. Yi, W.; Zhang, P.; Wang, Y.; Li, Z.; Guo, Y.; Liu, M.; Dong, C.; Li, C. Copper ferrite nanoparticles loaded on reduced graphene oxide nanozymes for the ultrasensitive colorimetric assay of chromium ions. Anal. Methods 2022, 14, 3434–3443. [Google Scholar] [CrossRef]
  91. Lou, C.; Yang, F.; Zhu, L.; Sun, Q.; Yang, Y.; Guo, J. Dual-function sensor based on NH2-MIL-101(Fe)@Cu/CeO2 nanozyme for colorimetric and fluorescence detection of heavy metals. Colloids Surfaces A Physicochem. Eng. Asp. 2023, 677, 132398. [Google Scholar] [CrossRef]
  92. Liu, P.; Li, X.; Xu, X.; Ye, K.; Wang, L.; Zhu, H.; Wang, M.; Niu, X. Integrating peroxidase-mimicking activity with photoluminescence into one framework structure for high-performance ratiometric fluorescent pesticide sensing. Sensors Actuators B Chem. 2021, 328, 129024. [Google Scholar] [CrossRef]
  93. Chen, L.; Zhu, X.; Tang, J.; Ouyang, X.; Liao, Y.; Lu, Y.; Wang, J.; Wei, Z.; Xi, B.; Tang, L. Porous Fe/CeO2 Nanozyme-Based Hydrogel Colorimetric Platform for on-Site Detection of Kanamycin. ACS ES&T Water 2023, 3, 2318–2327. [Google Scholar] [CrossRef]
  94. Che, H.; Tian, X.; Guo, F.; Nie, Y.; Dai, C.; Li, Y.; Lu, L. Enhancement of the Peroxidase Activity of g-C3N4 with Different Morphologies for Simultaneous Detection of Multiple Antibiotics. Anal. Chem. 2023, 95, 12550–12556. [Google Scholar] [CrossRef] [PubMed]
  95. Kaur, N.; Khunger, A.; Wallen, S.L.; Kaushik, A.; Chaudhary, G.R.; Varma, R.S. Advanced green analytical chemistry for environmental pesticide detection. Curr. Opin. Green Sustain. Chem. 2021, 30, 100488. [Google Scholar] [CrossRef]
  96. Banerjee, D.; Adhikary, S.; Bhattacharya, S.; Chakraborty, A.; Dutta, S.; Chatterjee, S.; Ganguly, A.; Nanda, S.; Rajak, P. Breaking boundaries: Artificial intelligence for pesticide detection and eco-friendly degradation. Environ. Res. 2024, 241, 117601. [Google Scholar] [CrossRef]
  97. Xu, W.; Kang, Y.; Jiao, L.; Wu, Y.; Yan, H.; Li, J.; Gu, W.; Song, W.; Zhu, C. Tuning Atomically Dispersed Fe Sites in Metal–Organic Frameworks Boosts Peroxidase-Like Activity for Sensitive Biosensing. Nano-Micro Lett. 2020, 12, 1–12. [Google Scholar] [CrossRef]
  98. Zhang, Y.; Yang, J.; Gao, W.; Liu, S.G.; Zhao, Q.; Fu, Z.; Shi, X. A smartphone-integrated colorimetric sensor for sensitive detection of organophosphorus pesticides based on large-scale synthesized Fe-N/C single-atom nanozymes. Sens. Actuators B Chem. 2024, 403, 135130. [Google Scholar] [CrossRef]
  99. Wang, J.; Huang, R.; Qi, W.; Su, R.; He, Z. Construction of biomimetic nanozyme with high laccase- and catecholase-like activity for oxidation and detection of phenolic compounds. J. Hazard. Mater. 2022, 429, 128404. [Google Scholar] [CrossRef] [PubMed]
  100. Wu, P.; Zhang, Z.; Luo, Y.; Bai, Y.; Fan, J. Bioremediation of phenolic pollutants by algae—Current status and challenges. Bioresour. Technol. 2022, 350, 126930. [Google Scholar] [CrossRef] [PubMed]
  101. Zhang, B.; Wang, X.; Hu, W.; Liao, Y.; He, Y.; Dong, B.; Zhao, M.; Ma, Y. SPR-Enhanced Au@Fe3O4 Nanozyme for the Detection of Hydroquinone. Chemosensors 2023, 11, 392. [Google Scholar] [CrossRef]
  102. Chu, S.; Xia, M.; Xu, P.; Lin, D.; Jiang, Y.; Lu, Y. Single-atom Fe nanozymes with excellent oxidase-like and laccase-like activity for colorimetric detection of ascorbic acid and hydroquinone. Anal. Bioanal. Chem. 2023, 416, 1–11. [Google Scholar] [CrossRef] [PubMed]
  103. Hou, C.; Cheng, D.; Zou, S.; Gao, J.; Wang, J.; Wang, Y. Rational design of magnetic MOFs-COFs hybrid nanozyme for the colorimetric detection of phenol. J. Environ. Chem. Eng. 2023, 11, 110914. [Google Scholar] [CrossRef]
Water 16 03431 g001
Figure 1. Schematic diagram of the preparation process of (a) Fe-MoS2 nanozyme [45] and (b) MIL-88B (Fe, Ni) nanozyme [51].
Figure 1. Schematic diagram of the preparation process of (a) Fe-MoS2 nanozyme [45] and (b) MIL-88B (Fe, Ni) nanozyme [51].
Water 16 03431 g001
Water 16 03431 g003
Figure 3. Pollutant detection mechanism diagram of (a) NH2-MIL-101(Fe)@Cu/CeO2 nanozyme [91] and (b) NH2-MIL-101(Fe) nanozyme [92].
Figure 3. Pollutant detection mechanism diagram of (a) NH2-MIL-101(Fe)@Cu/CeO2 nanozyme [91] and (b) NH2-MIL-101(Fe) nanozyme [92].
Water 16 03431 g003
Table 1. Common preparation methods for iron-based nanozymes.
Table 1. Common preparation methods for iron-based nanozymes.
Preparation MethodAdvantageDisadvantageNanozymeActivity TypeRef.
Hydrothermal methodNarrow size distribution; High purity
High crystallinity
Controlled morphology		High temperature and pressure range
Security risks
Limited scope of application		MoSe2@FePeroxidase[44]
MoS2Peroxidase[45]
Fe-CDsPeroxidase[46]
Fe, N-CDsPeroxidase[47]
MNP@CTSPeroxidase[48]
Solvothermal methodWider adjustment range
Ability to adapt to more synthetic needs		Higher costs
High chemical toxicity
High risk		FeS2@SNW-1Peroxidase[49]
N-CDs/Fe3O4Peroxidase[50]
MIL-88B (Fe, Ni)Peroxidase[51]
Co-precipitation methodSimple operation
High yield
Short reaction time		Uneven composition
Prone to agglomeration
Lower crystallinity		Ni/Al-Fe(CN)6 LDHPeroxidase[52]
Fe3(PO4)2·8H2O-CDs-FAPeroxidase[53]
Fe/CuSn(OH)6Peroxidase[54]
Fe3O4 MNPszymolyase[55]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Cao, X.; Fan, G.; Wu, S.; Luo, J.; Lin, Y.; Zheng, W.; Min, S.; Xu, K.-Q. Preparation of Iron-Based Nanozymes and Their Application in Water Environment: A Review. Water 2024, 16, 3431. https://doi.org/10.3390/w16233431

AMA Style

Cao X, Fan G, Wu S, Luo J, Lin Y, Zheng W, Min S, Xu K-Q. Preparation of Iron-Based Nanozymes and Their Application in Water Environment: A Review. Water. 2024; 16(23):3431. https://doi.org/10.3390/w16233431

Chicago/Turabian Style

Cao, Xingfeng, Gongduan Fan, Shiyun Wu, Jing Luo, Yuhan Lin, Weixin Zheng, Shuangyu Min, and Kai-Qin Xu. 2024. "Preparation of Iron-Based Nanozymes and Their Application in Water Environment: A Review" Water 16, no. 23: 3431. https://doi.org/10.3390/w16233431

APA Style

Cao, X., Fan, G., Wu, S., Luo, J., Lin, Y., Zheng, W., Min, S., & Xu, K. -Q. (2024). Preparation of Iron-Based Nanozymes and Their Application in Water Environment: A Review. Water, 16(23), 3431. https://doi.org/10.3390/w16233431

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop