CN101618322A - Photocatalysis antibacterial material excited by visible light and application thereof - Google Patents

Abstract

The invention relates to a photocatalytic antibacterial material excited by visible light and its application. It is characterized in that any metal of Pd, Pt, Au or Ag noble metal or Cu and Ni is loaded on the Bi _{2 WO 6 material in the form of nitrate while Bi 2 WO 6 is} generated to form metal-supported Bi ₂ WO ₆ material system. By adjusting the amount of the loaded noble metal or any one of Ni and Cu, the control of the loading amount is realized. The amount of metal loaded is 0.0025M-0.05M. Combining the synergy between noble metals or any one of Ni and Cu and semiconductors, the visible light photocatalytic antibacterial performance of Bi _{2 WO 6 is greatly improved by loading noble metals on the surface of Bi 2} WO ₆ , and the antibacterial rate reaches over 99.9% after 30 minutes of light irradiation. The loading process is simple, and it is a potential visible light photocatalytic antibacterial material. It overcomes the limitation that an ultraviolet light source must be added when photocatalytic materials are used outdoors or indoors. If sunlight is used as a light source, the utilization rate of sunlight can be greatly improved.

Description

Visible light-excited photocatalytic antibacterial materials and their applications

technical field

The invention relates to a photocatalytic antibacterial material excited by visible light, which is used for sewage treatment, indoor and outdoor air purification and sterilization, as well as various building material fields such as coatings, glass, lamps, roads, and daily necessities.

Background technique

Since Fujishima (Nature, 238 (1972), 37-38) first discovered in 1972 that single crystal TiO ₂ electrodes can photocatalytically split water, Carey et al. successfully used TiO ₂ for photocatalytic degradation of organic pollutants in water, semiconductor Photocatalysis has quickly attracted widespread attention from environmental and energy researchers in various countries. Due to some shortcomings of the traditional water disinfection technology, such as chlorination disinfection, research shows that it will produce toxic by-products that are harmful to human health, so the traditional water disinfection technology cannot be well promoted. In 1985, Japanese scientist Matsunaga (FEMS Microbiology Letters 29 (1985), 211-214) found that TiO ₂ has a bactericidal effect under ultraviolet light irradiation. This discovery makes photocatalytic technology have the potential to replace traditional water disinfection technology. Due to the advantages of safety, stability and low cost, TiO ₂ has been extensively studied for its photocatalytic antibacterial properties. However, _TiO2 only responds in the ultraviolet range, and the ultraviolet light with a wavelength below 400nm is less than 5% of the total energy of sunlight. Therefore, in order to improve the utilization rate of solar energy, a new type of photocatalyst that responds to visible light has been mentioned on the agenda. There are currently two main ideas in the research of new photocatalytic antimicrobial agents that respond to visible light: one is to modify TiO ₂ to redshift the response wavelength to the visible region, mainly including metal/non-metal doping, dye photosensitization, narrow-band Semiconductor (CdS, etc.) recombination and other means. The other is to design new visible light-responsive nano-photocatalytic materials, and this research direction has attracted more and more attention.

Bi ₂ WO ₆ is one of the simplest composite oxides in the Aurivillius family, and its molecular formula is Bi ₂ A _n-1 B _n O _3n+3 (A=Ca, Sr, Ba, Pb, Bi, Na, K, B =Ti, Nb, Ta, Mo, W, Fe). Previous literature reports on Bi ₂ WO ₆ showed that (J.Phys.Chem.B, 109(2005), 22432-22439): Bi ₂ WO ₆ has high photocatalytic degradation activity of organic matter and good stability. are getting more and more attention.

Contents of the invention

The purpose of the present invention is to provide a non-TiO ₂ system, photocatalytic antibacterial material excited by visible light and its application. The visible photocatalytic antibacterial material Bi ₂ WO ₆ material and metal-supported Bi ₂ WO ₆ material system, the latter has not been reported so far, the metal is a noble metal including Ag, Pt, Pd or Au, and also includes Ni Or metal supported Bi ₂ WO ₆ such as Cu. In order to achieve the improvement of its photocatalytic antibacterial performance.

The metal-supported Bi ₂ WO ₆ material system is characterized in that Pd, Pt, Au or Ag noble metal or any metal in Cu and Ni is supported on Bi _{2 WO 6 in the form of nitrate while Bi 2 WO 6} is generated. On the WO ₆ material, a metal-supported Bi ₂ WO ₆ material system is formed. The load control is achieved by adjusting the quality of the loaded noble metal or any one of Ni and Cu. The amount of metal loaded is 0.0025M-0.05M.

The preparation of Bi ₂ WO ₆ loaded noble metal or metal is:

(a) 0.01M～0.1M Bi(NO ₃ ) ₃ ·5H ₂ O and 0.01M～0.1M Na ₂ WO ₄ ·2H ₂ O are used as raw materials, according to the stoichiometric ratio of Bi ₂ WO ₆ , add 0.025 M～0.05M nitrates of metal-loaded ions are stirred into a precursor solution with ethanol, glycerol or ethylene glycol as a solvent;

(b) putting the precursor solution prepared in step a into a hydrothermal kettle, and heat-treating at 100-200°C;

(c) filter the precipitate after the reaction in step b, first wash with deionized water, then with absolute ethanol, and then dry at 40-80°C;

The metal supporting ion is any one of Pt, Pd, Au or Ag noble metal and Ni or Cu.

in,

(1) The heat treatment time of the hydrothermal kettle is 6～24 hours in the step b;

(2) Filtration in step c is to use deionized water first, and then wash with absolute ethanol for 5 to 10 times;

(3) Ethanol, glycerol or ethylene glycol is used as both a solvent and a reducing agent for metal sources.

The components provided by the present invention are Bi ₂ WO ₆ and its metal-supported Bi ₂ WO ₆ material system, combined with the synergistic effect of noble metals or any metal among Ni and Cu and Bi ₂ WO ₆ , under the irradiation of visible light, it can In a short period of time, it has a good inhibitory effect on Gram-negative bacteria Escherichia coli, Gram-positive bacteria surface Staphylococcus, Staphylococcus aureus, etc.

The visible light photocatalytic antibacterial material of the present invention has good photocatalytic antibacterial activity under outdoor sunlight and indoor natural light, improves the utilization rate of visible light, and also overcomes the fact that the photocatalytic material can only be used outdoors or indoors. The limitations of the UV light source must be added. At the same time, a method for supporting noble metals and Cu or Ni is provided to improve its performance.

Description of drawings

Fig. 1 is the Bi ₂ WO ₆ XRD diffraction pattern prepared in embodiment 1;

Figure 2 is the picture of plate counting experiment results: A. Blank sample; B. No sample with light for 2 hours; C. Add sample with no light for 2 hours; D. Add sample with light for 2 hours;

Fig. 3 is the antibacterial curve of Bi ₂ WO ₆ ;

Figure 4 is the XRD diffraction pattern of Ag loaded Bi ₂ WO ₆ ;

Figure 5 is the UV/Vis diffuse reflectance spectrum of Ag loaded Bi ₂ WO ₆ ;

Fig. 6 is a bar graph of the antibacterial rate of pure Bi ₂ WO ₆ and Ag-loaded Bi ₂ WO ₆ .

Detailed ways

Example 1 Preparation of pure Bi ₂ WO ₆ and its use in the detection of photocatalytic antibacterial activity

Bi ₂ WO ₆ was synthesized using Bi(NO ₃ ) ₂ ·5H ₂ O and Na ₂ WO ₄ ·2H ₂ O as raw materials. According to the stoichiometric ratio, 0.97g Bi(NO ₃ ) ₂ ·5H ₂ O (analytical pure ) was dissolved in 20 mL of water, then 0.210 g of citric acid was added, stirred for 30 minutes, 0.329 g of Na ₂ WO ₄ ·2H ₂ O (analytical grade) was dissolved in 20 mL of water, and the two were mixed and stirred to form a white suspension precursor. Then take a certain volume and put it into a hydrothermal kettle, and treat it at a temperature of 180° C. for 24 hours. After the reaction, the obtained pale yellow precipitate was filtered, washed with deionized water and absolute ethanol five times each, and then dried at 80°C. As shown in Figure 1, it was determined to be Bi ₂ WO ₆ by XRD phase analysis. Through the measurement of the UV/Visible diffuse reflectance spectrum of the product, the photocatalyst has photoresponse from the ultraviolet region to the visible region, and the estimated band gap is 2.76eV.

The photocatalytic antibacterial activity of prepared Bi ₂ WO ₆ was estimated by plate counting method. Escherichia coli cultured with LB medium overnight, collected, centrifuged, washed three times with 0.9% physiological saline, and finally diluted to ~10 ⁷ cfu/ml suspension for future use. A 500W-Xe lamp is used as the light source, and a λ>420nm filter is added to ensure that the ultraviolet band is filtered out. The photocatalyst concentration is 0.5mg/ml, and the antibacterial efficiency reaches more than 95% after 2 hours of light. As shown in Figure 2, the results of two comparative experiments without adding samples for 2 hours of light and adding samples for 2 hours without light showed that the number of bacteria basically did not change, indicating that the tested samples themselves were not toxic to bacteria. Two comparative experiments show that Bi ₂ WO ₆ has a killing effect on bacteria and has antibacterial properties under light.

Example 2 Preparation of Bi ₂ WO ₆ materials loaded with different amounts of Ag ions and their use in photocatalytic antibacterial testing

a) The whole system is an ethanol system, stir 0.01M Bi(NO ₃ ) ₂ ·5H ₂ O (analytical pure) and 0.01M Na ₂ WO ₄ ·2H ₂ O (analytical pure) evenly, add 0.0025M AgNO _3. Stir for 10 minutes to mix evenly. Then take a certain volume of the precursor and put it into a hydrothermal kettle, and treat it at a temperature of 160°C for 24 hours. After the reaction, the obtained precipitate was filtered, washed with deionized water and absolute ethanol five times each, and then dried at 60°C. As shown in Figure 4, due to the small amount of Ag, the characteristic peak of Ag cannot be clearly seen in the XRD spectrum (AB-0.1), but it can be seen in the UV/Vis diffuse reflectance spectrum caused by the surface plasmon resonance absorption of Ag At the same time, Ag peaks can be seen in the energy spectrum, and the combination of the two can confirm that the loading of Ag has been successfully achieved. Visible light photocatalytic antibacterial experiment results show that the photocatalytic antibacterial performance of Ag loaded Bi ₂ WO ₆ is greatly improved. After 30 minutes of light, the antibacterial rate reaches 99%.

b) The whole system is glycerol system, stir 0.1M Bi(NO ₃ ) ₂ ·5H ₂ O (analytical pure) and 0.1M Na ₂ WO ₄ ·2H ₂ O (analytical pure) evenly, add 0.05M AgNO ₃ , stirred for 10 minutes to mix well. Then take a certain volume of the precursor and put it into a hydrothermal kettle, and treat it at a temperature of 160°C for 24 hours. After the reaction, the obtained precipitate was filtered, washed with deionized water and then with absolute ethanol for 8 times, and then dried at 60°C. The characteristic peak of Ag can be clearly seen in the XRD spectrum (AB-1.0), and the bulge caused by the surface plasmon resonance absorption of Ag can also be seen in the UV/Vis diffuse reflectance spectrum (Figure 5). As shown in Figure 6, the visible light photocatalytic antibacterial experiment results show that the photocatalytic antibacterial performance is slightly higher than that of Example 1, and is similar to that of Example (a).

c) The whole system is an ethylene glycol system. Stir 0.05M Bi(NO ₃ ) ₂ ·5H ₂ O (analytical pure) and 0.05M Na ₂ WO ₄ ·2H ₂ O (analytical pure) evenly, add 0.005M AgNO ₃ , stirred for 10 minutes to mix well. Then take a certain volume of the precursor and put it into a hydrothermal kettle, and treat it at a temperature of 160°C for 24 hours. After the reaction, the obtained precipitate was filtered, washed with deionized water and then with absolute ethanol for 10 times, and then dried at 60°C. The product was determined to be Ag/Bi ₂ WO ₆ by XRD and energy spectrum composition analysis, and the photocatalytic antibacterial performance of Ag-loaded Bi ₂ WO ₆ was greatly improved. After 30 minutes of light, the antibacterial rate reaches 99.9%.

In this example, Ag loading was replaced by Pd, Pt or Au with similar results.

Example 3 Preparation of Ni ion-loaded Bi ₂ WO ₆ material and its use in photocatalytic antibacterial testing

The whole system is ethylene glycol system, 0.05M Bi(NO ₃ ) ₂ 5H ₂ O (analytical pure) and 0.05M Na ₂ WO ₄ 2H ₂ O (analytical pure) are stirred evenly, and 0.005M Ni (NO ₃ ) ₂ ·6H ₂ O, stirred for 10 minutes, and mixed evenly. Then take a certain volume of the precursor and put it into a hydrothermal kettle, and treat it at a temperature of 160°C for 24 hours. After the reaction, the obtained precipitate was filtered, washed with deionized water and absolute ethanol five times each, and then dried at 60°C. The product was determined to be Ni/Bi ₂ WO ₆ by XRD and energy spectrum composition analysis, and the photocatalytic antibacterial performance of Ni-loaded Bi ₂ WO ₆ was greatly improved. After 30 minutes of light, the antibacterial rate reaches 99%. All the other are with embodiment 2.

Example 4 Preparation of Cu ion-loaded Bi ₂ WO ₆ material and its use in photocatalytic antibacterial testing

The whole system is a glycerol system. Stir 0.1M Bi(NO ₃ ) ₂ ·5H ₂ O (analytical pure) and 0.1M Na ₂ WO ₄ ·2H ₂ O (analytical pure) evenly, add 0.05M Cu (NO ₃ ) ₂ ·3H ₂ O, stirred for 10 minutes, and mixed evenly. Then take a certain volume of the precursor and put it into a hydrothermal kettle, and treat it at a temperature of 160°C for 24 hours. After the reaction, the obtained precipitate was filtered, washed with deionized water and absolute ethanol 8 times each, and then dried at 60°C. The product was identified as Cu/Bi ₂ WO ₆ by XRD and energy spectrum composition analysis, and the photocatalytic antibacterial performance of Cu loaded Bi ₂ WO ₆ was greatly improved. The photocatalytic antibacterial performance is slightly higher than that of Example 1, and slightly lower than that of Example 2 (c). All the other are with embodiment 2.

Claims (8)

1. Photocatalytic materials excited by visible light, including Bi ₂ WO ₆ , characterized in that Pd, Pt, Au or Ag noble metal or any metal of Cu and Ni is in the form of nitrate, and Bi ₂ WO ₆ is generated at the same time loaded onto Bi ₂ WO ₆ material to form a metal supported Bi ₂ WO ₆ material system. 2. The visible light-excited photocatalytic material according to claim 1, characterized in that the loading amount is controlled by adjusting the weight of the loaded noble metal or any one of Ni and Cu. 3. The visible light-excited photocatalytic material according to claim 1 or 2, characterized in that the amount of supported metal is 0.0025M-0.05M. 4. The method for preparing the photocatalytic material excited by visible light as claimed in claim 1, characterized in that it comprises: (a) 0.01M～0.1M Bi(NO ₃ ) ₃ ·5H ₂ O and 0.01M～0.1M Na ₂ WO ₄ ·2H ₂ O are used as raw materials, according to the stoichiometric ratio of Bi ₂ WO ₆ , add 0.025 M～0.05M nitrates of metal-loaded ions are stirred into a precursor solution with ethanol, glycerol or ethylene glycol as a solvent; (b) putting the precursor solution prepared in step a into a hydrothermal kettle, and heat-treating at 100-200°C; (c) Filtration of the precipitate after the reaction in step b is first washed with deionized water, then washed with absolute ethanol, and then dried at 40-80°C; The metal supporting ion is any one of Pt, Pd, Au or Ag noble metal and Ni or Cu. 5. The method for preparing photocatalytic materials excited by visible light according to claim 4, characterized in that: (1) The heat treatment time of the hydrothermal kettle is 6～24 hours in the step b; (2) Filtration in step c is performed by first washing with deionized water and then with absolute ethanol for 5 to 10 times. 6. The method for preparing photocatalytic materials excited by visible light according to claim 4, characterized in that ethanol, glycerol or ethylene glycol is also used as a reducing agent for the metal source. 7. The application of the photocatalytic material excited by visible light according to claim 1, characterized in that: (1) The pure Bi ₂ WO ₆ material has antibacterial properties under light, and the antibacterial efficiency is over 95%; (2) The Bi ₂ WO ₆ material system supported by Pt, Pd, Au or Ag noble metal; or any one of Ni and Cu has better antibacterial performance than Bi ₂ WO ₆ ; The bacteria are Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus surface or Staphylococcus aureus. 8. The application of the photocatalytic material excited by visible light according to claim 1, characterized in that: a) The photocatalytic antibacterial property of Ag-loaded Bi ₂ WO ₆ material, under 30min light, the antibacterial rate reaches 99-99.9%; b) The photocatalytic antibacterial property of Ni loaded Bi ₂ WO ₆ material, the antibacterial rate reached 99% under 30min light; c) The photocatalytic antibacterial activity of Cu-loaded _Bi2WO6 material _is higher than that of pure _{Bi2WO6 material} , but _lower than that of Ag-loaded _Bi2WO6 material.

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