Cs-WO3-X / Zn0. 5Cd0. 5S composite catalyst for photocatalytic hydrogen production as well as preparation method and application thereof

Abstract

The invention discloses a Cs-WO3-X / Zn0. 5Cd0. 5S composite catalyst for photocatalytic hydrogen production as well as a preparation method and application thereof, and belongs to the technical field of preparation of photocatalytic materials with visible spectrum response. The preparation method comprises the following steps: dissolving CsCl3, WCl6 and CO (NH2) 2 in ethanol, and carrying out hydrothermal reaction to obtain Cs-WO3-x powder; the preparation method comprises the following steps: dissolving CdCl2. 5H2O, ZnCl2 and Na2S. 9H2O in water, then adding the Cs-WO3-x powder, stirring at room temperature, centrifuging, washing and drying to obtain the Cs-WO3-X / Zn0. 5Cd0. 5S composite catalyst. The Cs-WO3-X / Zn0. 5Cd0. 5S composite heterojunction catalyst prepared by the preparation method disclosed by the invention integrates the advantages of single Cs-WO3-X and single Zn0. 5Cd0. 5S, and a heterojunction is constructed to form a built-in electric field, so that carrier recombination is inhibited by the heterojunction, the light absorption rate is improved, and the hydrogen evolution yield is improved.

Description

Technical Field

[0001] This invention belongs to the field of visible spectrum-responsive photocatalytic material preparation technology, specifically relating to a Cs-WO3 material for photocatalytic hydrogen production. 3-X / Zn 0.5 Cd 0.5 S-composite catalysts, their preparation methods, and applications. Background Technology

[0002] Hydrogen is a widely used and promising new energy source, thanks to its numerous advantages, such as a highly clean and environmentally friendly atmosphere, zero emissions during combustion (producing only water), and a lower hydrogen content (142 kJ·kg⁻¹) compared to traditional hydrocarbon fuels. -1 Due to its superior calorific value, current research on hydrogen energy mainly focuses on hydrogen production, transportation, hydrogen production through electricity, combustion, green hydrogen production, performance, safety, and life cycle assessment. Widely used hydrogen production processes include fossil fuel-based hydrogen production and water electrolysis. Fossil fuel-based hydrogen production still relies on traditional fossil fuels such as methane, and environmental pollution is unavoidable during the process. Water electrolysis produces hydrogen at the cathode and oxygen at the anode. While this process produces no other byproducts, it still depends on an external power source and inevitably causes environmental pollution. As the efficient conversion of solar energy into hydrogen energy becomes a research hotspot, photocatalysis technology has emerged.

[0003] Photocatalytic water splitting is a technology that uses light energy to catalyze the splitting of water to produce hydrogen, offering advantages such as being green, environmentally friendly, and sustainable. However, most photocatalytic semiconductors can only absorb ultraviolet light and some short-wavelength visible light, failing to absorb most visible and near-infrared light, resulting in extremely low utilization of sunlight. Therefore, broadening the light absorption range of photocatalysts and utilizing infrared irradiation-driven hydrogen evolution is crucial for the utilization, conversion, and storage of solar energy, and is a key research topic in the field of photocatalysis.

[0004] Zn 0.5 Cd 0.5 S is a ternary metal sulfide with strong visible light absorption capabilities, which can fully utilize sunlight to excite and complete the catalytic cracking of water to produce hydrogen. However, due to severe carrier recombination, it exhibits unsatisfactory photocatalytic efficiency.

[0005] To address the aforementioned technical problems, the present invention aims to provide an innovative method for preparing a photocatalytic hydrogen production agent, which involves doping Cs with oxygen vacancies (O... V ) Defects leading to non-stoichiometric forms of WO 3-x Improve WO 3-x Oxygen vacancies (O V) concentration, to enhance absorption capacity in the ultraviolet-visible region, through WO 3-x The surface plasmon resonance (LSPR) effect enhances its absorption of near-infrared light and reduces WO3. 3-x The bandgap width, and Zn 0.5 Cd 0.5 S constructs a heterojunction, and with WO 3-X / Zn 0.5 Cd 0.5 Compared to S composite catalysts, Cs-WO 3-X / Zn 0.5 Cd 0.5 S-composite catalysts can more effectively improve solar energy utilization, possess stronger charge separation capabilities, and more effectively suppress carrier recombination, thus promoting e-carrier synthesis. - —h + The separation further enhances Zn 0.5 Cd 0.5 S photocatalytic activity. In summary, Cs-WO3 was prepared. 3-X / Zn 0.5 Cd 0.5 S composite catalyst is a photocatalyst with full-spectrum response and high photocatalytic efficiency. Summary of the Invention

[0006] To solve or partially solve the problems existing in related technologies, the present invention provides a Cs-WO3 for photocatalytic hydrogen production. 3-X / Zn 0.5 Cd 0.5 S-composite catalysts, their preparation methods, and applications.

[0007] This invention provides a Cs-WO3 for photocatalytic hydrogen production. 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst includes the following steps: (1) Dissolve CsCl3, WCl6 and CO(NH2)2 in ethanol, then add water and continue stirring until the solution is colorless and transparent to prepare a precursor solution; (2) The precursor solution was subjected to a hydrothermal reaction, the sample was collected by centrifugation and dried to obtain Cs-WO3. 3-x powder; (3) Dissolve CdCl2·2.5H2O, ZnCl2 and Na2S·9H2O in water to prepare a precursor solution; (4) Cs-WO 3-x The powder was added to the precursor solution from step (3), stirred at room temperature, centrifuged, washed, and dried to obtain Cs-WO. 3-X / Zn 0.5 Cd0.5 S composite catalyst.

[0008] Preferably, the mass ratio of WCl6 to CO(NH2)2 is 10:1, and the molar ratio of Cs to W in CsCl3 and WCl6 is 1%.

[0009] Preferably, in step (1), the volume ratio of ethanol to water is 80:1.

[0010] Preferably, the hydrothermal reaction is carried out at a temperature of 180-200°C for 18 hours.

[0011] Preferably, the molar ratio of CdCl2·2.5H2O, ZnCl2, and Na2S·9H2O is 1:1:10.

[0012] Preferably, the Cs-WO 3-x Powder and Zn 0.5 Cd 0.5 The mass ratio of S is 3%.

[0013] Preferably, in step (4), the stirring time at room temperature is 1 hour.

[0014] This invention also claims protection for the Cs-WO3 used in photocatalytic hydrogen production. 3-X / Zn 0.5 Cd 0.5 Cs-WO3 prepared by the method of preparing S composite catalyst 3-X / Zn 0.5 Cd 0.5 S composite catalyst, Zn 0.5 Cd 0.5 S-coated in Cs-WO 3-X Above, Cs-WO 3-X Cs-doped WO 3-X Materials, and Cs-WO 3-X Contains oxygen vacancies, 0 <X<1。

[0015] This invention also claims protection for the Cs-WO3 used in photocatalytic hydrogen production. 3-X / Zn 0.5 Cd 0.5 Application of S composite catalyst in photocatalytic hydrogen production.

[0016] The technical solution provided by this invention has the following beneficial effects: the Cs-WO prepared by this invention 3-X / Zn 0.5 Cd 0.5 S-composite heterojunction catalyst combines the properties of single Cs-WO3 catalysts. 3-X and single Zn 0.5 Cd 0.5The advantages of S are utilized, and a heterojunction is constructed to form a built-in electric field. The heterojunction suppresses carrier recombination, improves light absorption, and increases hydrogen evolution yield. Attached Figure Description

[0017] Figure 1 Cs-WO prepared in Example 1 of this invention 3-X SEM image.

[0018] Figure 2 Cs-WO prepared in Example 1 of this invention 3-X XRD pattern.

[0019] Figure 3 Cs-WO prepared in Example 1 of this invention 3-X / Zn 0.5 Cd 0.5 Scanning electron microscope image of the S composite catalyst.

[0020] Figure 4 Cs-WO prepared in Example 1 of this invention 3-X / Zn 0.5 Cd 0.5 Transmission electron microscopy image of the S composite catalyst.

[0021] Figure 5 Cs-WO prepared in Example 1 of this invention 3-X / Zn 0.5 Cd 0.5 XRD pattern of the S composite catalyst.

[0022] Figure 6 Cs-WO prepared in Example 1 of this invention 3-X / Zn 0.5 Cd 0.5 S composite catalyst and Zn prepared in Comparative Example 2 0.5 Cd 0.5 Hydrogen production performance diagram of S. Detailed Implementation Example 1

[0023] A Cs-WO3 photocatalytic hydrogen production method 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst includes the following steps: (1) Prepare 9g·ml -1A CsCl3 anhydrous ethanol solution was prepared. Next, 0.8 g of WCl6 and 0.08 g of CO(NH2)2 were accurately weighed and transferred to a 100 ml beaker. 4 ml of the prepared CsCl3 was added dropwise to the beaker, making the molar ratio of Cs to W 1%. Then, 76 ml of anhydrous ethanol was added to the beaker to bring the total anhydrous ethanol content to 80 ml. The solution was stirred with a magnetic stirrer at room temperature for 1 h until completely dissolved. 1 ml of deionized water was slowly added dropwise while continuing to stir with a magnetic stirrer until the solution became colorless and transparent. The solution was then placed in a 100 ml tetrafluoroethylene-lined container and sealed in a hydrothermal reactor. The reactor was incubated at 200 °C for 18 h. After natural cooling, the precipitate was washed three times by centrifugation using deionized water and anhydrous ethanol, respectively. The centrifuged product was ultrasonically dispersed in deionized water and dried in a drying oven at 30 °C for 24 h to obtain blue Cs-WO3. 3-x Powder. Its electron microscope image is as follows: Figure 1 The nanowires are visibly arranged in a uniform and orderly manner. (Cs-WO) 3-x XRD characterization of powder as follows Figure 2 As can be seen from the figure, Cs-WO 3-X It exhibits good crystallinity, is stable in phase, and does not show diffraction peaks of other phases.

[0024] (2) Dissolve 0.128g CdCl2·2.5H2O, 0.076g ZnCl2 and 1.345g Na2S·9H2O in 30ml of deionized water, and take 0.01g Cs-WO3. 3-x The powder was ultrasonically vibrated, then added to a beaker and stirred at room temperature for 1 hour. After centrifugation with ethanol, washing, and drying, a yellow powder was obtained, yielding Cs-WO3. 3-X / Zn 0.5 Cd 0.5 The S composite catalyst, and its scanning electron microscope (SEM) and transmission electron microscope (TEM) images are shown below. Figure 3 , Figure 4 As shown, by Figure 3 Zn can be clearly observed 0.5 Cd 0.5 S quantum dots coated with Cs-W 3-X Nanowires; Figure 4 It can be seen that Cs-WO 3-X With Zn 0.5 Cd 0.5 The S-contact was good, and a heterojunction was successfully formed. The XRD characterization of the composite catalyst is as follows: Figure 5 As can be seen from the figure, Cs-WO 3-X and Zn 0.5 Cd 0.5 Both S and S exhibit good crystallinity and phase stability, with no diffraction peaks from other phases.

[0025] Comparative Example 1 A Cs-WO 3-X The catalyst preparation method includes the following steps: 9g·ml -1 A CsCl3 anhydrous ethanol solution was prepared. Next, 0.8 g of WCl6 and 0.08 g of CO(NH2)2 were accurately weighed and transferred to a 100 ml beaker. 4 ml of the prepared CsCl3 was added dropwise to the beaker, making the molar ratio of Cs to W 1%. Then, 76 ml of anhydrous ethanol was added to the beaker to bring the total anhydrous ethanol content to 80 ml. The solution was stirred with a magnetic stirrer at room temperature for 1 h until completely dissolved. 1 ml of deionized water was slowly added dropwise while continuing to stir with a magnetic stirrer until the solution became colorless and transparent. The solution was then placed in a 100 ml tetrafluoroethylene-lined container and sealed in a hydrothermal reactor. The reactor was incubated at 200 °C for 18 h. After natural cooling, the precipitate was washed three times by centrifugation using deionized water and anhydrous ethanol, respectively. The centrifuged product was ultrasonically dispersed in deionized water and dried in a drying oven at 30 °C for 24 h to obtain blue Cs-WO3. 3-x powder.

[0026] Comparative Example 2 A type of Zn 0.5 Cd 0.5 The preparation method of S catalyst includes the following steps: Dissolve 0.128 g CdCl2·2.5H2O, 0.076 g ZnCl2, and 1.328 g Na2S·9H2O in 30 ml of deionized water, stir at room temperature for 1 h, centrifuge with ethanol, wash, and dry to obtain a yellow powder, thus yielding Zn. 0.5 Cd 0.5 S catalyst.

[0027] Comparative Example 3 A kind of WO 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst includes the following steps: (1) Accurately weigh 0.8 g WCl6 and 0.08 g CO(NH2)2 respectively and transfer them to a 100 ml beaker. Then, add 80 ml of anhydrous ethanol to the beaker and stir with a magnetic stirrer at room temperature for 1 h until completely dissolved. Slowly add 1 ml of deionized water and continue stirring with a magnetic stirrer until the solution becomes colorless and transparent. Then, place it in a 100 ml tetrafluoroethylene-lined container and transfer it to a hydrothermal reactor and seal it. Keep it at 200 ℃ for 18 h. After natural cooling, wash the precipitate three times by centrifugation with deionized water and anhydrous ethanol respectively. Sonicately disperse the centrifuged product in deionized water and dry it in a drying oven at 30 ℃ for 24 h to obtain WO3. 3-x powder.

[0028] (2) Dissolve 0.128g CdCl2·2.5H2O, 0.076g ZnCl2 and 1.328g Na2S·9H2O in 30ml of deionized water, and take 0.01g WO3. 3-x The powder was ultrasonically vibrated, then added to a beaker and stirred at room temperature for 1 hour. After centrifugation with ethanol, washing, and drying, a yellow powder was obtained, yielding WO3. 3-X / Zn 0.5 Cd 0.5 S composite catalyst.

[0029] Example of effect Photocatalytic hydrogen production experiments were conducted using the catalysts prepared in Example 1 and Comparative Examples 1-3. These experiments were performed in a Pofil Labsolar-6A all-glass automated online trace gas analysis system. The obtained gas products were analyzed online using a Fulli GC9790Plus-TCD (thermal conductivity detector) gas chromatograph. The experiments were conducted as follows: 10 ml of 98% pure lactic acid was used as a sacrificial agent. A mixed solution of 0.01 g catalyst and 30 ml deionized water was added to a quartz reactor and mixed thoroughly. The mixture was stirred with a magnetic stirrer throughout the reaction. Circulating cooling water was used to maintain the temperature of the quartz reactor at 10°C. Before the reaction began, the quartz reactor was evacuated. After evacuation, a 300W full-spectrum xenon lamp was used to irradiate the reactants in the reactor. During the two-and-a-half-hour reaction period, gaseous products of the reaction system were collected every half hour and analyzed online by gas chromatography. The collected gaseous products were quantitatively analyzed using a thermal conductivity detector in a gas chromatograph. The results are shown in Table 1 and [Table data missing]. Figure 6 .

[0030] Table 1 Hydrogen production at 2.5 h (μmol / g) Example 1 44759 Comparative Example 1 250 Comparative Example 2 9068 Comparative Example 3 31127 The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A Cs-WO3 photocatalytic hydrogen production method 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: Includes the following steps: (1) Dissolve CsCl3, WCl6 and CO(NH2)2 in ethanol, then add water and continue stirring until the solution is colorless and transparent to prepare a precursor solution; (2) The precursor solution was subjected to a hydrothermal reaction, the sample was collected by centrifugation and dried to obtain Cs-WO3. 3-x powder; (3) Dissolve CdCl2·2.5H2O, ZnCl2 and Na2S·9H2O in water to prepare a precursor solution; (4) Cs-WO 3-x The powder was added to the precursor solution from step (3), stirred at room temperature, centrifuged, washed, and dried to obtain Cs-WO. 3-X / Zn 0.5 Cd 0.5 S composite catalyst.

2. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: The mass ratio of WCl6 to CO(NH2)2 is 10:1, and the molar ratio of Cs to W in CsCl3 and WCl6 is 1%.

3. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: In step (1), the volume ratio of ethanol to water is 80:

1.

4. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: The hydrothermal reaction was carried out at a temperature of 200°C for 18 hours.

5. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: The molar ratio of CdCl2·2.5H2O, ZnCl2, and Na2S·9H2O is 1:1:

10.

6. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: The Cs-WO 3-X Powder and Zn 0.5 Cd 0.5 The mass ratio of S is 3%.

7. The Cs-WO3 for photocatalytic hydrogen production according to claim 1 3-X / Zn 0.5 Cd 0.5 The preparation method of the S composite catalyst is characterized by: In step (4), the stirring time at room temperature is 1 hour.

8. The Cs-WO3 for photocatalytic hydrogen production according to any one of claims 1-7 3-X / Zn 0.5 Cd 0.5 Cs-WO3 prepared by the method of preparing S composite catalyst 3-X / Zn 0.5 Cd 0.5 S composite catalyst, Zn 0.5 Cd 0.5 S-coated in Cs-WO 3-X Up, 0 <X<1,Cs-WO 3-X Cs-doped WO 3-X Materials, and Cs-WO 3-X It contains oxygen vacancies.

9. The Cs-WO3 for photocatalytic hydrogen production according to claim 8 3-X / Zn 0.5 Cd 0.5 Application of S composite catalyst in photocatalytic hydrogen production.

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