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Novel Nanocatalysts for Sustainable and Green Chemistry
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Novel Nanocatalysts for Sustainable and Green Chemistry

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Nanostructured Catalysts".

Deadline for manuscript submissions: 20 March 2025 | Viewed by 7231

Special Issue Editor

Dr. Elisabete C.B.A. Alegria

E-Mail Website
Guest Editor
Departamento de Engenharia Química, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, 1959-007 Lisboa, Portugal
Interests: sustainable homogeneous and supported catalysis; oxidation catalysis; green synthesis of metallic nanoparticles; mechanochemistry (synthesis and catalysis); molecular electrochemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

I am delighted to invite you to contribute to the upcoming Special Issue "Novel Nanocatalysts for Sustainable and Green Chemistry," where we aim to showcase cutting-edge research at the intersection of nanotechnology and environmentally friendly chemistry. As the Guest Editor, I recognize the indispensable role that nanocatalysts play in advancing sustainable practices within chemical processes. This Special Issue provides a unique platform for researchers to disseminate their pioneering findings, methodologies, and advancements in the design and application of novel nanocatalysts, with a dedicated emphasis on promoting green and sustainable chemistry.

Topics of interest include, but are not limited to, the following:

- The synthesis and characterization of new nanocatalysts;

- Catalytic processes for green and sustainable chemistry;

- The environmental impact and life cycle analysis of nanocatalysts;

- The integration of nanotechnology in industrial processes for eco-friendly production.

Contributions from diverse perspectives and research backgrounds are highly encouraged to foster a comprehensive understanding of this crucial field. Join us in shaping the future of sustainable chemistry by submitting your latest research to this Special Issue. I look forward to your valuable contributions.

Dr. Elisabete C.B.A. Alegria
Guest Editor

Manuscript Submission Information

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Keywords

  • nanocatalysis
  • sustainable chemistry
  • nanostructured catalyst design
  • biocompatible nanocatalysts
  • eco-friendly catalytic processes
  • industrial sustainability
  • nanomaterials for carbon capture
  • green nanotechnology

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Published Papers (7 papers)

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Research

14 pages, 2127 KiB  
Article
Boosting Hydrogen Evolution via Phase Engineering-Modulated Crystallinity of Ruthenium–Zinc Bimetallic MOFs
by Jia Wang, De Wang, Tianci Huang, Zhenyu He, Yong Cui and Junsheng Li
Catalysts 2025, 15(1), 58; https://doi.org/10.3390/catal15010058 (registering DOI) - 9 Jan 2025
Abstract
The systematic design of ruthenium-based electrocatalysts for the hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production via electrocatalytic water splitting in an alkaline medium. However, the mismatch between water dissociation and hydrogen adsorption kinetics limits its HER activity. Herein, we present [...] Read more.
The systematic design of ruthenium-based electrocatalysts for the hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production via electrocatalytic water splitting in an alkaline medium. However, the mismatch between water dissociation and hydrogen adsorption kinetics limits its HER activity. Herein, we present a phase engineering-modulated strategy to develop an ultrasmall ZnRu bimetallic metal–organic framework electrocatalyst (ZnRu30-ZIF) for catalyzing alkaline HER. Experimental results and density functional theory calculations indicate that the incorporation of Ru atoms modifies the crystal structure of the ZIF-8 phase, resulting in enlarged facet spacing and smaller nanocrystals (45 ± 3 nm). This optimization of the crystal structure regulates the electronic properties of the ZnRu30-ZIF, forming a higher d-band center (−5.91 eV), which reduces the water dissociation energy (0.19 eV) and facilitates hydrogen desorption (ΔGH* = 1.09 eV). The prepared ZnRu30-ZIF exhibits a low overpotential of 48 mV at 10 mA cm−2 and an excellent mass activity of 2.9 A mgRu−1 at 0.1 V (vs. RHE). This work establishes a phase-engineering strategy for the preparation of high-performance Ru-based MOF electrocatalysts for HER. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Graphical abstract

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Full article ">
18 pages, 2518 KiB  
Article
Evaluation of Cobalt, Nickel, and Palladium Complexes as Catalysts for the Hydrogenation and Improvement of Oxidative Stability of Biodiesel
by Fortunate P. Sejie, Olayinka A. Oyetunji, Banothile C. E. Makhubela, James Darkwa and Nora H. de Leeuw
Catalysts 2024, 14(9), 653; https://doi.org/10.3390/catal14090653 - 23 Sep 2024
Viewed by 851
Abstract
Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized [...] Read more.
Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)pyridin-2-ylmethylimine and N-(3-(triethoxysilyl)propyl)picolinamide were synthesized, characterized, and used as pre-catalysts in the transfer hydrogenation of C=C bonds in fatty acid methyl esters. The active catalysts from the Co, Ni, and Pd complexes sequentially hydrogenate the C18:2 chains to C18:1, which is further converted to C18:0 in the FAMEs of both methyl linoleate and jatropha biodiesel. The hydrogenation process was kinetically controlled, and after 3 h it yielded a biodiesel sample that contained 25.83% C16:0, 12.52% C18:2, 41.54% C18:1, 14.47% C18:0 and 3.0% C18:2 isomers. The un-hydrogenated jatropha diesel, hydrogenated jatropha diesel, and a B20 blend of jatropha were tested for susceptibility to oxidation reactions using the Rancimat method and FTIR spectroscopy, and the partial hydrogenation had improved the induction period by 3 h. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Figure 1

Figure 1
<p>The structural determination of complex <b>C6-Pd</b> using <sup>1</sup>H NMR.</p> Full article ">Figure 2
<p><sup>1</sup>H NMR spectra of the reaction mixture in the hydrogenation of methyl linoleate using catalyst <b>C6-Pd</b> sampled at different reaction times. Reaction conditions: ML (0.44 g), formic acid (40 mmol), catalyst (2.3 × 10<sup>−5</sup> mol), KOH (10 mmol), 120 °C, DCM solvent. Letters a–h represent the corresponding chemical shifts of the protons labelled in <a href="#catalysts-14-00653-sch003" class="html-scheme">Scheme 3</a>.</p> Full article ">Figure 3
<p>Gas chromatogram of Tonota jatropha biodiesel (BD1) before hydrogenation.</p> Full article ">Figure 4
<p>An example of the gas chromatogram of the reaction mixture after 12 h of hydrogenation of BD1 using <b>C4</b> (<b>a</b>) with a zoomed-in area of the chromatogram (<b>b</b>) showing the C18:1 component.</p> Full article ">Figure 5
<p>An example of the GC chromatogram of the reaction mixture obtained for entry 7<sup>a</sup> in <a href="#catalysts-14-00653-t003" class="html-table">Table 3</a>.</p> Full article ">Figure 6
<p>Nature of the complex formed between the substrate and the active metal center of the catalysts, which can take place between the two C=C (I) to through only one C=C (II) interactions.</p> Full article ">Figure 7
<p>The comparison of the fuel properties of the biodiesels (BD1, BD2, and BD3).</p> Full article ">Figure 8
<p>(<b>a</b>) Changes in the induction time of the biodiesel samples before and after hydrogenation in comparison with the effect of blending (BD1: jatropha biodiesel; H-BD1: partially hydrogenated jatropha biodiesel; BD1-BL: jatropha biodiesel blended with 20% LP5). (<b>b</b>) Comparative study of the density, kinematic viscosity, and induction period of the fuel samples: un-hydrogenated (BD1), partially hydrogenated BD1 (H-BD1), and jatropha biodiesel blended with 20% LP5 (BD1-BL).</p> Full article ">Figure 9
<p>The FTIR analysis of the jatropha biodiesel (BD1), partially hydrogenated jatropha biodiesel (H-BD1), Un-hydrogenated jatropha biodiesel blended with 20% LP5 (BD1–20), and the diesel samples after 6 months of storage at room temperature.</p> Full article ">Scheme 1
<p>(<b>a</b>) Reaction scheme for the synthesis of ligand <b>L1</b> and the corresponding metal complexes. (<b>b</b>) Reaction scheme for the synthesis of ligand <b>L2</b> and the corresponding metal complexes.</p> Full article ">Scheme 2
<p>Transesterification of linoleic acid.</p> Full article ">Scheme 3
<p>Hydrogenation of methyl linoleate to methyl stearate through the formation of methyl oleate as an intermediate. Letters a–h represent the protons expected from the labelled components of fatty acid methyl esters.</p> Full article ">
14 pages, 28964 KiB  
Article
The Contradicting Influences of Silica and Titania Supports on the Properties of Au0 Nanoparticles as Catalysts for Reductions by Borohydride
by Gifty Sara Rolly, Alina Sermiagin, Krishnamoorthy Sathiyan, Dan Meyerstein and Tomer Zidki
Catalysts 2024, 14(9), 606; https://doi.org/10.3390/catal14090606 - 9 Sep 2024
Cited by 1 | Viewed by 736
Abstract
This study investigates the significant impact of metal–support interactions on catalytic reaction mechanisms at the interface of oxide-supported metal nanoparticles. The distinct and contrasting effects of SiO2 and TiO2 supports on reaction dynamics using NaBD4 were studied and focused on [...] Read more.
This study investigates the significant impact of metal–support interactions on catalytic reaction mechanisms at the interface of oxide-supported metal nanoparticles. The distinct and contrasting effects of SiO2 and TiO2 supports on reaction dynamics using NaBD4 were studied and focused on the relative yields of [HD]/[H2] and [D2]/[H2]. The findings show a consistent increase in HD yields with rising [BD4−] concentrations. Notably, the sequence of HD yield enhancement follows the order of TiO2-Au0-NPs < Au0-NPs < SiO2-Au0-NPs. Conversely, the rate of H2 evolution during BH4- hydrolysis exhibits an inverse trend, with TiO2-Au0-NPs outperforming the others, followed by Au0-NPs and SiO2-Au0-NPs, demonstrating the opposing effects exerted by the TiO2 and SiO2 supports on the catalytic processes. Further, the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) confirms the catalytic mechanism, with TiO2-Au0-NPs demonstrating superior activity. The catalytic activity observed aligns with the order of TiO2-Au0-NPs > Au0-NPs > SiO2-Au0-NPs, suggesting that SiO2 donates electrons to Au0-NPs, while TiO2 withdraws them. It is of interest to note that two very different processes, that clearly proceed via different mechanisms, are affected similarly by the supports. This study reveals that the choice of support material influences catalytic activity, impacting overall yield and efficiency. These findings underscore the importance of selecting appropriate support materials for tailored catalytic outcomes. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>TEM images of (<b>A</b>–<b>C</b>) Au<sup>0</sup>-NPs (4.2 nm), (<b>D</b>–<b>F</b>) SiO<sub>2</sub>-Au<sup>0</sup>-NPs (Au<sup>0</sup> = 3.5 nm), and (<b>G</b>–<b>I</b>) TiO<sub>2</sub>-Au<sup>0</sup>-NPs (Au<sup>0</sup> = 3.8 nm) at different scales.</p> Full article ">Figure 2
<p>EDX spectra of Au<sup>0</sup>-NPs (<b>A</b>), SiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>B</b>), and TiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>C</b>).</p> Full article ">Figure 3
<p>PXRD of Au<sup>0</sup>-NPs (<b>A</b>), SiO<sub>2</sub>-Au<sup>0</sup>-NPs and SiO<sub>2</sub> (<b>B</b>), and TiO<sub>2</sub>-Au<sup>0</sup>-NPs and TiO<sub>2</sub> (<b>C</b>).</p> Full article ">Figure 4
<p>The correlations between %HD and %D<sub>2</sub>, as obtained for the NaBD<sub>4</sub> reaction with bare Au<sup>0</sup>-NPs (<b>A</b>,<b>B</b>), SiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>C</b>,<b>D</b>), and TiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>E</b>,<b>F</b>).</p> Full article ">Figure 5
<p>Kinetic plots of hydrogen formation in the hydrolysis of BH<sub>4</sub><sup>−</sup> in the presence of Au<sup>0</sup>-NPs (<b>A</b>), SiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>B</b>), TiO<sub>2</sub>-Au<sup>0</sup>-NPs (<b>C</b>) at pH 9.0 and the dependence of the observed rate constants on [Au<sup>0</sup>] (<b>D</b>). [BH<sub>4</sub><sup>−</sup>] = 0.50 mM, pH 9.0, the ratios [Au<sup>0</sup>/TiO<sub>2</sub>] and [Au<sup>0</sup>/SiO<sub>2</sub>] were constant. Note [Au<sup>0</sup>] was the [Au<sup>III</sup>] used to prepare the NPs, and [TiO<sub>2</sub>] was the [TiCl<sub>4</sub>] used to prepare NPs.</p> Full article ">Figure 6
<p>Time-dependent UV-visible spectra of the catalytic reduction of 4-nitrophenol using SiO<sub>2</sub>-Au<sup>0</sup>-NPs, TiO<sub>2</sub>-Au<sup>0</sup>-NPs, and bare Au<sup>0</sup>-NPs at pH 9.0. The time interval between the cycles was 0.050 min. The concentration of gold was 0.020 mM (in terms of the [Au<sup>III</sup>] used to prepare the NPs). For better clarity, the absorption spectra shown are at intervals of 0.30 min for TiO<sub>2</sub>-Au<sup>0</sup>-NPs and 0.70 min for Au<sup>0</sup>-NPs and SiO<sub>2</sub>-Au<sup>0</sup>-NPs.</p> Full article ">Figure 7
<p>Kinetic traces of 4-NP reduction monitored at 400 nm using SiO<sub>2</sub>-Au<sup>0</sup>-NPs, TiO<sub>2</sub>-Au<sup>0</sup>-NPs, and bare Au<sup>0</sup>-NPs measured every 0.050 min. The concentration of gold was 0.020 mM (in terms of the [Au<sup>III</sup>] used to prepare the NPs).</p> Full article ">Scheme 1
<p>The catalytic reduction of 4-NP to 4-AP by NaBH<sub>4</sub> on Au<sup>0</sup>-NPs, SiO<sub>2</sub>-Au<sup>0</sup>-NPs, and TiO<sub>2</sub>-Au<sup>0</sup>-NPs catalysts.</p> Full article ">
18 pages, 2411 KiB  
Article
Heterogeneous Photo-Fenton Degradation of Azo Dyes over a Magnetite-Based Catalyst: Kinetic and Thermodynamic Studies
by Jackson Anderson S. Ribeiro, Júlia F. Alves, Bruno César B. Salgado, Alcineia C. Oliveira, Rinaldo S. Araújo and Enrique Rodríguez-Castellón
Catalysts 2024, 14(9), 591; https://doi.org/10.3390/catal14090591 - 3 Sep 2024
Viewed by 953
Abstract
Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the [...] Read more.
Textile wastewater containing dyes poses significant environmental hazards. Advanced oxidative processes, especially the heterogeneous photo-Fenton process, are effective in degrading a wide range of contaminants due to high conversion rates and ease of catalyst recovery. This study evaluates the heterogeneous photodegradation of the azo dyes Acid Red 18 (AR18), Acid Red 66 (AR66), and Orange 2 (OR2) using magnetite as a catalyst. The magnetic catalyst was synthesized via a hydrothermal process at 150 °C. Experiments were conducted at room temperature, investigating the effect of catalyst dosage, pH, and initial concentrations of H2O2 and AR18 dye. Kinetic and thermodynamic studies were performed at 25, 40, and 60 °C for the three azo dyes (AR18, AR66, and OR2) and the effect of the dye structures on the degradation efficiency was investigated. At 25 °C for 0.33 mmolL−1 of dye at pH 3.0, using 1.4 gL−1 of the catalyst and 60 mgL−1 of H2O2 under UV radiation of 16.7 mWcm−2, the catalyst showed 62.3% degradation for AR18, 79.6% for AR66, and 83.8% for OR2 in 180 min of reaction. The oxidation of azo dyes under these conditions is spontaneous and endothermic. The pseudo-first-order kinetic constants indicated a strong temperature dependence with an order of reactivity of the type OR2 > AR66 > AR18, which is associated with the molecular size, steric hindrance, aromatic conjugation, electrostatic repulsion, and nature of the acid–base interactions on the catalytic surface. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Figure 1

Figure 1
<p>Effects of AR18 degradation at 25 °C with <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>. (<b>a</b>) Initial catalyst dosage using a <span class="html-italic">C</span><sub>0</sub>(AR18) of ca. 60 mgL<sup>−1</sup> and <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) of ca. 30 mgL<sup>−1</sup> at a pH of 3.0 during 120 min of reaction time. (<b>b</b>) Blank runs of the degradation of AR18 over magnetite in distinct reaction conditions. <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(AR18) = 60 mgL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>, and a pH of 3.0 at 120 min.</p> Full article ">Figure 2
<p>(<b>a</b>) Influence of pH with an initial catalyst dosage <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) of 1.4 gL<sup>−1</sup> at a fixed condition of <span class="html-italic">C</span><sub>0</sub>(AR18) = 60 mgL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 30 mgL<sup>−1</sup> within 120 min. (<b>b</b>) Influence of the initial H<sub>2</sub>O<sub>2</sub> concentration using <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) of 1.4 gL<sup>−1</sup> and <span class="html-italic">C</span><sub>0</sub>(AR18) of about 60 mgL<sup>−1</sup> at a pH of 3.0 for 120 min. (<b>c</b>) Effect of <span class="html-italic">C</span><sub>0</sub>(AR18) with a <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) of 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) of 60 mgL<sup>−1</sup>, and a pH of 3.0 for 120 min. (<b>d</b>) Reuse of the Fe<sub>3</sub>O<sub>4</sub> at 25 °C after the heterogeneous photo-Fenton reaction using a 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(AR18) of 60 mg L<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mW cm<sup>−2</sup>, at a pH of 3.0 and <span class="html-italic">t</span> = 120 min.</p> Full article ">Figure 3
<p>Degradation of AR18, AR66, and OR2 in a heterogeneous photo-Fenton-like process as a function of time. Reaction conditions: <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(dye) = 0.33 mmolL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mg L<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>, and a pH of ca. 3.0.</p> Full article ">Figure 4
<p>Arrhenius plots for heterogeneous photo-Fenton degradation of AR18, AR66, and OR2. <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(dye) = 0.33 mmolL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>, and a pH of ca. 3.0.</p> Full article ">Figure 5
<p>The van’t Hoff plots for the heterogeneous photo-Fenton degradation of AR18, AR66, and OR2. <span class="html-italic">C</span><sub>0</sub>(Fe<sub>3</sub>O<sub>4</sub>) = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(dye) = 0.33 mmolL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>, and a pH of ca. 3.0.</p> Full article ">Figure 6
<p>Azo dye structures in a study adapted from <a href="http://worlddyevariety.com" target="_blank">worlddyevariety.com</a> (accessed on 28 August 2024). (<b>a</b>) OR2. (<b>b</b>) AR18. (<b>c</b>) AR66.</p> Full article ">Figure 7
<p>Comparison of the degradation efficiency of the AR18 azo dye at 25 °C over distinct iron catalysts via the heterogeneous photo-Fenton process. Catalyst dosage = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(AR18) = 60 mgL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup>, and a pH of 3.0 at 180 min. <sup>a</sup> Synthesized according to [<a href="#B47-catalysts-14-00591" class="html-bibr">47</a>], <sup>b</sup> Synthesized according to [<a href="#B48-catalysts-14-00591" class="html-bibr">48</a>], <sup>c</sup> Commercial (Sigma-Aldrich, St. Louis, MO, USA), and <sup>d</sup> synthesized in this work.</p> Full article ">Figure 8
<p>UV–Vis spectra of Orange 2 as a function of reaction time at 60 °C in the heterogeneous photo-Fenton-like reaction. Catalyst dosage = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(dye) = 0.33 mmolL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, and <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup> at a pH of 3.0.</p> Full article ">Figure 9
<p>XPS spectra of Fe 2<span class="html-italic">p</span> core levels for magnetite. (<b>a</b>) Fresh Fe<sub>3</sub>O<sub>4</sub>, and after the heterogeneous photo-Fenton-like process with (<b>b</b>) AR18 and (<b>c</b>) AR 66. Reaction conditions: Catalyst dosage = 1.4 gL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(dye) = 0.33 mmolL<sup>−1</sup>, <span class="html-italic">C</span><sub>0</sub>(H<sub>2</sub>O<sub>2</sub>) = 60 mgL<sup>−1</sup>, and <span class="html-italic">I<sub>L</sub></span> = 16.7 mWcm<sup>−2</sup> at a pH of 3.0 at 60 °C.</p> Full article ">
24 pages, 5842 KiB  
Article
Porous Nanostructured Catalysts Based on Silicates and Their Surface Functionality: Effects of Silica Source and Metal Added in Glycerol Valorization
by José Vitor C. Carmo, Joabson Nogueira, Gabriela M. Bertoldo, Francisco E. Clemente, Alcineia C. Oliveira, Adriana F. Campos, Gian C. S. Duarte, Samuel Tehuacanero-Cuapa, José Jiménez-Jiménez and Enrique Rodríguez-Castellón
Catalysts 2024, 14(8), 526; https://doi.org/10.3390/catal14080526 - 15 Aug 2024
Viewed by 880
Abstract
A series of nanospherical-shaped silicates containing heteroatoms (Al, Zr or Ti) were successfully synthesized using tetraethylorthosilicate (TEOS) or silica colloids as a silicon source. These metallosilicate nanospheres were used as silicon nutrients to obtain silicalite zeolites with micro-mesoporosity and improved textural properties. The [...] Read more.
A series of nanospherical-shaped silicates containing heteroatoms (Al, Zr or Ti) were successfully synthesized using tetraethylorthosilicate (TEOS) or silica colloids as a silicon source. These metallosilicate nanospheres were used as silicon nutrients to obtain silicalite zeolites with micro-mesoporosity and improved textural properties. The results demonstrated that TEOS acted as a suitable silicon source to produce amorphous silicates and a spherical-type zeolite architecture with Zr and Ti heteroatoms included in their framework, with preferable particle size and crystallinity. The surface functionality of the mesostructured nanospheres and zeolite silicates provide active centers for the esterification of glycerol with acetic acid (EG) reaction. The dispersion of Cu entities on the surface of the zeolites achieved high glycerol conversions selectively producing triacetin in comparison with Fe counterparts. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Figure 1
<p>SEM micrographs, EDS mappings and EDS spectra of the as-synthesized silica-based nanospheres obtained by using the following silica sources: (<b>a</b>) TEOS and (<b>b</b>) colloidal silica. The included figures are the magnified regions of the images.</p> Full article ">Figure 1 Cont.
<p>SEM micrographs, EDS mappings and EDS spectra of the as-synthesized silica-based nanospheres obtained by using the following silica sources: (<b>a</b>) TEOS and (<b>b</b>) colloidal silica. The included figures are the magnified regions of the images.</p> Full article ">Figure 2
<p>SEM micrographs of calcined samples: (<b>a</b>) silica-based mesostructured spheres, and (<b>b</b>) as-synthesized silica-seeded mesostructured zeolites.</p> Full article ">Figure 2 Cont.
<p>SEM micrographs of calcined samples: (<b>a</b>) silica-based mesostructured spheres, and (<b>b</b>) as-synthesized silica-seeded mesostructured zeolites.</p> Full article ">Figure 3
<p>(<b>a</b>) Nitrogen physisorption isotherms and (<b>b</b>) pore-size distributions of the as-synthesized silica-based mesostructured spheres.</p> Full article ">Figure 4
<p>XRD patterns of the solids in study: (<b>a</b>) as-synthesized silica-based mesostructured spheres, (<b>b</b>) calcined silica-based mesostructured spheres and (<b>c</b>) calcined silica-seeded mesostructured zeolites.</p> Full article ">Figure 5
<p>FTIR spectra of the (<b>a</b>) as-synthesized silica-based mesostructured spheres, (<b>b</b>) calcined silica-based mesostructured spheres and (<b>c</b>) calcined silica-seeded mesostructured zeolites. The included figure is the FTIR spectrum of NZ-SAT sample.</p> Full article ">Figure 6
<p>Representative XPS spectra of selected solids: (<b>a</b>) XPS survey spectrum, (<b>b</b>) Si 2<span class="html-italic">p</span>, (<b>c</b>) O 1<span class="html-italic">s</span>, (<b>d</b>) Na 1<span class="html-italic">s</span>, (<b>e</b>) C 1<span class="html-italic">s</span> and (<b>f</b>) Al 2<span class="html-italic">p</span> core-level spectra for NZ-SAT. The XPS spectra of the STT-C and SZT-C samples corresponding to the (<b>g</b>) Ti 2<span class="html-italic">p</span> and (<b>h</b>) Zr 3<span class="html-italic">d</span> core levels.</p> Full article ">Figure 6 Cont.
<p>Representative XPS spectra of selected solids: (<b>a</b>) XPS survey spectrum, (<b>b</b>) Si 2<span class="html-italic">p</span>, (<b>c</b>) O 1<span class="html-italic">s</span>, (<b>d</b>) Na 1<span class="html-italic">s</span>, (<b>e</b>) C 1<span class="html-italic">s</span> and (<b>f</b>) Al 2<span class="html-italic">p</span> core-level spectra for NZ-SAT. The XPS spectra of the STT-C and SZT-C samples corresponding to the (<b>g</b>) Ti 2<span class="html-italic">p</span> and (<b>h</b>) Zr 3<span class="html-italic">d</span> core levels.</p> Full article ">Figure 7
<p>The catalytic performance of the (<b>a</b>) solids in the EG reaction, and (<b>b</b>) effects of Fe and Cu on the catalytic performance of the most active solids.</p> Full article ">Figure 8
<p>Schematic representation of the synthetic route used to produce the obtained solids: (<b>a</b>) as-synthesized silica-based mesostructured spheres prepared from TEOS and colloidal silica sources, (<b>b</b>) silica-seeded mesostructured zeolites synthesis.</p> Full article ">
14 pages, 1950 KiB  
Article
One-Pot Phyto-Mediated Synthesis of Fe2O3/Fe3O4 Binary Mixed Nanocomposite Efficiently Applied in Wastewater Remediation by Photo-Fenton Reaction
by Amr A. Essawy, Tamer H. A. Hasanin, Modather. F. Hussein, Emam F. El Agammy and Abd El-Naby I. Essawy
Catalysts 2024, 14(7), 466; https://doi.org/10.3390/catal14070466 - 20 Jul 2024
Cited by 1 | Viewed by 1292
Abstract
A binary Fe2O3/Fe3O4 mixed nanocomposite was prepared by phyto-mediated avenue to be suited in the photo-Fenton photodegradation of methylene blue (MB) in the presence of H2O2. XRD and SEM analyses illustrated that [...] Read more.
A binary Fe2O3/Fe3O4 mixed nanocomposite was prepared by phyto-mediated avenue to be suited in the photo-Fenton photodegradation of methylene blue (MB) in the presence of H2O2. XRD and SEM analyses illustrated that Fe2O3 nanoparticles of average crystallite size 8.43 nm were successfully mixed with plate-like aggregates of Fe3O4 with a 15.1 nm average crystallite size. Moreover, SEM images showed a porous morphology for the binary Fe2O3/Fe3O4 mixed nanocomposite that is favorable for a photocatalyst. EDX and elemental mapping showed intense iron and oxygen peaks, confirming composite purity and symmetrical distribution. FTIR analysis displayed the distinct Fe-O assignments. Moreover, the isotherm of the developed nanocomposite showed slit-shaped pores in loose particulates within plate-like aggregates and a mesoporous pore-size distribution. Thermal gravimetric analysis (TGA) indicated the high thermal stability of the prepared Fe2O3/Fe3O4 binary nanocomposite. The optical properties illustrated a narrowing in the band gab (Eg = 2.92 eV) that enabled considerable absorption in the visible region of solar light. Suiting the developed binary Fe2O3/Fe3O4 nanocomposite in the photo-Fenton reaction along with H2O2 supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. The solar-driven photodegradation reactions were conducted and the estimated rate constants were 0.002, 0.0047, and 0.0143 min−1 when using the Fe2O3/Fe3O4 nanocomposite, pure H2O2, and the Fe2O3/Fe3O4/H2O2 hybrid catalyst, respectively. Therefore, suiting the developed binary Fe2O3/Fe3O4 nanocomposite and H2O2 in photo-Fenton reaction supplied higher productivity of active oxidizing species and accordingly a higher degradation efficacy of MB. After being subjected to four photo-Fenton degradation cycles, the Fe2O3/Fe3O4 nanocomposite catalyst still functioned admirably. Further evaluation of Fe2O3/Fe3O4 nanocomposite in photocatalytic remediation of contaminated water using a mixture of MB and pyronine Y (PY) dyestuffs revealed substantial dye photodegradation efficiencies. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Figure 1
<p>XRD pattern with Rietveld refinement. (<b>A</b>) FTIR spectrum; (<b>B</b>) TGA profile; (<b>C</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 2
<p>SEM image. (<b>A</b>) EDX spectrum; (<b>B</b>) EDS mapping; (<b>C</b>–<b>E</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 3
<p>N<sub>2</sub> adsorption–desorption isotherm (<b>A</b>) and pore size distribution (<b>B</b>) of the developed binary Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">Figure 4
<p>UV–Visible electronic spectra of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite (<b>A</b>) and the corresponding plot of (<span class="html-italic">αhυ</span>)<sup>1/2</sup> versus <span class="html-italic">hυ</span> (<b>B</b>).</p> Full article ">Figure 5
<p>Time-dependent variations in absorption spectrum of MB during the solar-driven photo-Fenton catalytic degradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst (<b>A</b>) and the first order photodegradation kinetics for detoxification of MB using Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>, H<sub>2</sub>O<sub>2</sub>, and Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> catalysts (<b>B</b>).</p> Full article ">Figure 6
<p>Comparison of MB photodegradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>, H<sub>2</sub>O<sub>2</sub>, and Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> catalysts. (<b>A</b>) The durability study of the developed heterostructure during consecutive cycles of photo-Fenton processes (<b>B</b>).</p> Full article ">Figure 7
<p>The absorption spectra of a mixture of MB and PY dyestuff mixture before and after solar-driven photo-Fenton catalytic degradation in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst. (<b>A</b>) Comparison of the photodegradation efficiency of MB and PY in their mixture in presence of Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub>/H<sub>2</sub>O<sub>2</sub> hybrid catalyst (<b>B</b>).</p> Full article ">Figure 8
<p>A plausible mechanism for the solar-driven photo-Fenton degradation of MB in presence of biosynthesized Fe<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> nanocomposite.</p> Full article ">
16 pages, 8685 KiB  
Article
Platinum-Modified Rod-like Titania Mesocrystals with Enhanced Photocatalytic Activity
by Zhishun Wei, Yuanyuan Ji, Zuzanna Bielan, Xin Yue, Yuqi Xu, Jiajie Sun, Sha Chen, Guoqiang Yi, Ying Chang and Ewa Kowalska
Catalysts 2024, 14(4), 283; https://doi.org/10.3390/catal14040283 - 22 Apr 2024
Viewed by 1537
Abstract
Photocatalysis is considered as an environmentally friendly method for both solar energy conversion and environmental purification of water, wastewater, air, and surfaces. Among various photocatalytic materials, titania is still the most widely investigated and applied, but more efforts must be carried out considering [...] Read more.
Photocatalysis is considered as an environmentally friendly method for both solar energy conversion and environmental purification of water, wastewater, air, and surfaces. Among various photocatalytic materials, titania is still the most widely investigated and applied, but more efforts must be carried out considering the synthesis of highly efficient photocatalysts for multifarious applications. It is thought that nanoengineering design of titania morphology might be the best solution. Accordingly, here, titania mesocrystals, assembled from crystallographically oriented nanocrystals, have been synthesized by an easy, cheap, and “green” solvothermal method (without the use of surfactants and templates), followed by simple annealing. The obtained materials have been characterized by various methods, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and diffuse reflectance spectroscopy (DRS). It has been found that the as-obtained photocatalysts exhibit a unique nanorod-like subunit structure with excellent crystalline and surface properties. However, pristine titania is hardly active for a hydrogen evolution reaction, and thus additional modification has been performed by platinum photodeposition (and silver as a reference). Indeed, the modification with only 2 wt% of noble metals results in a significant enhancement in activity, i.e., ca. 75 and 550 times by silver- and platinum-modified samples, respectively, reaching the corresponding reaction rates of 37 μmol h−1 and 276 μmol h−1. Additionally, titania mesocrystals exhibit high oxidation power under simulated solar light irradiation for the degradation of antibiotics within the tetracycline group (tetracycline (TC), ciprofloxacin (CIP), norfloxacin (NOR) and oxytetracycline hydrochloride (OTC)). It has been found that both experimental results and the density functional theory (DFT) calculations confirm the high ability of titania mesocrystals for oxidative decomposition of tetracycline antibiotics. Full article
(This article belongs to the Special Issue Novel Nanocatalysts for Sustainable and Green Chemistry)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>XRD patterns of PTR and TR samples.</p> Full article ">Figure 2
<p>SEM images of PTR sample: (<b>a</b>) low magnification; (<b>b</b>) high magnification.</p> Full article ">Figure 3
<p>TEM observations of TR sample: (<b>a</b>) low magnification of TEM; (<b>b</b>) high magnification of TEM; (<b>c</b>) high resolution TEM (HR-TEM); (<b>d</b>) magnification of HR-TEM; and (<b>e</b>) SAED image.</p> Full article ">Figure 4
<p>TEM observations of Pt/TR sample: (<b>a</b>) TEM; (<b>b</b>) HR-TEM; and magnification of HR-TEM; (<b>c</b>) magnification of HR-TEM.</p> Full article ">Figure 5
<p>The deconvoluted XPS spectra for: (<b>a</b>) titanium (Ti 2p), (<b>b</b>) oxygen (O 1s), (<b>c</b>) carbon (C 1s) and (<b>d</b>) platinum (Pt 4f) of Pt/TR sample.</p> Full article ">Figure 6
<p>Photoabsorption properties of pristine and modified samples: (<b>a</b>) DRS spectra, and (<b>b</b>) Tauc plots.</p> Full article ">Figure 7
<p>Photocatalytic activity for H<sub>2</sub> generation on rod-like titania mesocrystals: unmodified (TR) and modified with platinum (Pt/TR) and silver (Ag/TR).</p> Full article ">Figure 8
<p>Photocatalytic activity of unmodified and modified titania mesocrystals: (<b>a</b>) efficiency of TC degradation; and (<b>b</b>) corresponding pseudo-first-order kinetics plots.</p> Full article ">Figure 9
<p>The results of photodegradation efficiency of Pt/RT against different antibiotics from tetracycline hydrochloride group.</p> Full article ">Figure 10
<p>The recycling experiments for photocatalytic degradation of TC (100 mL) on Pt/TR for photocatalyst content of: (<b>a</b>) 30 mg; and (<b>b</b>) 150 mg.</p> Full article ">Figure 11
<p>DFT calculation of: (<b>a</b>) optimized structure of TC; (<b>b</b>) ESP mapping of TC; (<b>c</b>) the HOMO, and (<b>d</b>) the LUMO regions in TC; gray—carbon, red—oxygen, blue—nitrogen, white—hydrogen.</p> Full article ">Figure 12
<p>The photography of photoreactor system used for testing of hydrogen evolution reaction: (1) inlet of cooling water, (2) outlet of cooling water, (3) sample holder, (4) 400 W Hg lamp, (5) sample/tube reactors, (6) water bath, (7) magnetic stirrer.</p> Full article ">
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