Preparation of cadmium vacancy regulated zinc cadmium sulfide catalyst
The preparation of zinc cadmium sulfide catalysts regulated by cadmium vacancies solved the efficiency limitation of pure-phase zinc cadmium sulfide in photocatalytic water splitting, achieving high efficiency and stability in photocatalytic hydrogen production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-21
- Publication Date
- 2026-04-07
AI Technical Summary
Pure-phase zinc cadmium sulfide suffers from problems such as low visible light energy utilization efficiency, unsatisfactory photogenerated carrier separation efficiency, and insufficient surface catalytic activity in photocatalytic water splitting, which limit its catalytic efficiency.
The preparation method of zinc cadmium sulfide catalyst with cadmium vacancy regulation includes stirring the reaction solution at room temperature, ultrasonic treatment, hydrothermal reaction and washing of the precipitate to obtain zinc cadmium sulfide catalyst with cadmium vacancy.
It improved the separation efficiency of photogenerated electrons and holes, enhanced photocatalytic activity, and achieved a high photocatalytic hydrogen production rate of 27.17 mmol g⁻¹h⁻¹, while maintaining good stability in multiple cycle tests.
Smart Images
Figure HDA0005750972990000011 
Figure HDA0005750972990000012 
Figure HDA0005750972990000021
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of photocatalytic hydrogen evolution. BACKGROUND
[0002] As a clean and renewable energy source with abundant reserves, the efficient conversion and utilization of solar energy is one of the key paths to solve the global energy crisis and environmental problems. Solar-driven water splitting for hydrogen production has become a research hotspot in the field of sustainable energy due to its unique advantage of directly converting light energy into hydrogen energy. The light absorption range, photo-generated carrier separation efficiency and surface catalytic activity of the catalyst, as the core functional component of this technology, determine the energy conversion efficiency and industrial application prospect of water splitting for hydrogen production. Therefore, developing a catalyst material with wide spectral response, high carrier separation efficiency and stable catalytic performance is a technical bottleneck that needs to be broken through in this field.
[0003] As a kind of inorganic semiconductor material, cadmium zinc sulfide has a tunable band gap structure and a high light absorption coefficient, and has potential application value in the field of photocatalytic water splitting. However, the pure phase cadmium zinc sulfide has significant performance short boards. First, the intrinsic band gap is only suitable for the short-wave region of ultraviolet-visible light, and the utilization rate of visible light long-wave and near-infrared regions, which account for a higher proportion in the solar spectrum, is very low, and the solar energy capture efficiency is insufficient. Second, the photo-generated electron-hole separation ability is weak, and the recombination rate is fast, so a large number of carriers are deactivated without participating in the reaction, which seriously restricts the catalytic efficiency. Third, the number of surface catalytic active sites is limited and the activity is insufficient, which limits the kinetic rate of water splitting reaction. SUMMARY
[0004] In order to overcome the problems of low visible light energy utilization efficiency and unsatisfactory photo-generated carrier separation efficiency of cadmium zinc sulfide, the present application provides a preparation method of cadmium zinc sulfide catalyst with cadmium vacancy regulation.
[0005] The purpose of the present application is achieved as follows:
[0006] The preparation method of the cadmium zinc sulfide catalyst with cadmium vacancy regulation comprises the following steps:
[0007] (1) 1.08g of zinc acetate, 1.14g of cadmium chloride, 0.38g of thiourea and 0.45g of polyvinylpyrrolidone are weighed, and then added together into 36mL of deionized water, and continuously stirred at a stable stirring speed for 15 minutes at room temperature, so that the raw materials are fully dissolved and uniformly mixed to form a uniform reaction solution, and then 2mL of 40% mass fraction of hydrazine hydrate solution is added to the solution;
[0008] (2) The above solution is subjected to ultrasonic treatment, and the ultrasonic time is set to 30 minutes to further promote the dispersion and mixing between molecules and enhance the uniformity of the reaction system. After ultrasonic treatment, the solution is evenly divided into three parts and transferred into three 20mL reaction kettles respectively to ensure that the amount of reactants in each reaction kettle is consistent.
[0009] (3) The reaction kettle containing the reaction solution is placed in a blast drying oven with a set temperature of 220 DEG C, and the temperature is kept for 24 hours to make the reaction fully proceed. After the reaction is completed, the sample is naturally cooled to room temperature to avoid the influence of sudden temperature change on the structure of the product.
[0010] (4) The cooled sample is washed with deionized water and anhydrous ethanol respectively for three times to remove the impurities and unreacted raw materials possibly remaining on the surface of the sample. After washing, the precipitate is collected by centrifugation to obtain a yellow precipitate product. The precipitate product is placed in a blast drying oven with a temperature of 60 DEG C for drying for 24 hours to remove the water in the product, and finally the cadmium vacancy regulated zinc sulfide cadmium catalyst material is obtained.
[0011] The application method is as follows: 5mg of the cadmium vacancy regulated zinc sulfide cadmium is added into 20mL of deionized water containing 0.25mol of sodium sulfite and 0.35mol of sodium sulfide mixture, and after ultrasonic treatment, a uniform suspension is formed and then transferred into a 30mL reactor. A 500W xenon lamp equipped with a cutoff filter is placed on the side of the reactor, and the light experiment is started. During the experiment, 200ul of gas is extracted from the reactor every 1 hour, injected into a GC9800 type gas chromatograph to determine the hydrogen content and record it. The results show that the hydrogen production rate of the cadmium vacancy regulated zinc sulfide cadmium catalyst can reach 27.17mmol g -1 h -1 In addition, the catalyst is subjected to a continuous cycle test for 30 hours for a total of 5 times, and during the 5 cycles, the catalyst exhibits good stability, and the photocatalytic hydrogen production performance does not decrease significantly after the cycle test, which provides a strong stability guarantee for its practical application.
[0012] Compared with the prior art, the application has the following characteristics:
[0013] The one-step hydrothermal method greatly simplifies the preparation process, all reactions are completed in the same reaction kettle, and the interstitial site regulated zinc cadmium sulfide catalyst is prepared, the electron paramagnetic resonance test shows that the prepared interstitial site regulated zinc cadmium sulfide exists interstitial site, the photoluminescence spectrum shows that the interstitial site regulated zinc cadmium sulfide has lower fluorescence intensity than pure phase zinc cadmium sulfide, so that the photo-generated electrons can migrate more quickly, promoting the effective separation of photo-generated electrons and holes; the photoelectric current response test shows that the interstitial site regulated zinc cadmium sulfide has higher transient photocurrent intensity than pure phase zinc cadmium sulfide, which makes it have the ability to inhibit the recombination of photo-generated electrons and holes, and improves the separation efficiency of photo-generated electron-hole pairs, the hydrogen production rate of the interstitial site regulated zinc cadmium sulfide of the present application under visible light reaches 27.17 mmol g -1 h -1 , and in the multiple cycle test, the catalyst can still maintain good structural stability and catalytic activity, the interstitial site regulated zinc cadmium sulfide catalyst of the present application is applied to the field of photocatalytic water hydrogen production. BRIEF DESCRIPTION OF DRAWINGS
[0014] Figure 1 The X-ray diffraction pattern of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application.
[0015] Figure 2 The scanning electron microscope image of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application.
[0016] Figure 3 The electron paramagnetic resonance comparison chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application and pure phase zinc cadmium sulfide.
[0017] Figure 4 The electrochemical impedance comparison chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application and pure phase zinc cadmium sulfide.
[0018] Figure 5 The photoluminescence comparison chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application and pure phase zinc cadmium sulfide.
[0019] Figure 6 The photoelectric current response comparison chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application and pure phase zinc cadmium sulfide.
[0020] Figure 7 The hydrogen production rate comparison chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application and pure phase zinc cadmium sulfide.
[0021] Figure 8 The hydrogen production cycle test chart of the interstitial site regulated zinc cadmium sulfide catalyst prepared in Example 1 of the present application.
[0022] Figure 9 The X-ray diffraction patterns of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of this invention before and after cycle testing are shown.
[0023] Figure 10 This is a flowchart illustrating the preparation process of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention. Detailed Implementation
[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0025] Example 1 illustrates the application of vacancy-controlled zinc cadmium sulfide catalysts, comprising the following preparation steps:
[0026] (1) Weigh 1.08g of zinc acetate, 1.14g of cadmium chloride, 0.38g of thiourea and 0.45g of polyvinylpyrrolidone, and add them together to 36mL of deionized water. Stir at a stable stirring speed for 15 minutes at room temperature to fully dissolve and mix the raw materials to form a homogeneous reaction solution. Then add 2mL of 40% hydrazine hydrate solution to the solution.
[0027] (2) The above solution was subjected to ultrasonic treatment for 30 minutes to further promote the dispersion and mixing between molecules and enhance the uniformity of the reaction system. After ultrasonic treatment, the solution was divided into three equal parts and transferred to three 20 mL reaction vessels to ensure that the amount of reactants in each reaction vessel was consistent.
[0028] (3) Place the reaction vessel containing the reaction solution into a forced-air drying oven set at 220°C and maintain the temperature for 24 hours to allow the reaction to proceed fully. After the reaction is completed, allow the sample to cool naturally to room temperature to avoid the impact of sudden temperature changes on the product structure.
[0029] (4) After cooling, the sample was washed three times with deionized water and anhydrous ethanol to remove any impurities and unreacted raw materials that may remain on the sample surface. After washing, the precipitate was collected by centrifugation and a yellow precipitate was obtained. The precipitate was then dried in a forced-air drying oven at 60°C for 24 hours to remove the moisture and finally obtain the cadmium vacancy-controlled zinc cadmium sulfide catalyst material.
[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments: Attached Figure Description
[0032] (i) X-ray diffraction tests were performed on the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention. We compared it with the standard diffraction pattern and determined that the molecular formula of the vacancy-controlled zinc cadmium sulfide is ZnCdS (PDF#00-040-0835). The diffraction peaks at 2θ of 25.2°, 26.9°, 28.6°, 37.0°, 44.4°, 48.6° and 51.8° correspond to the (100), (002), (101), (102), (110), (103) and (200) crystal planes of zinc cadmium sulfide.
[0033] Figure 1 The image shows the X-ray diffraction pattern of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of this invention.
[0034] (ii) Scanning electron microscopy tests were performed on the zinc cadmium sulfide catalyst with vacancy control prepared in Example 1 of the present invention. It can be seen that the zinc cadmium sulfide with vacancy control exhibits a blocky morphology.
[0035] Figure 2 This is a scanning electron microscope image of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention.
[0036] (III) Electron paramagnetic resonance tests were performed on the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and the pure phase zinc cadmium sulfide. It can be seen that the vacancy-controlled zinc cadmium sulfide has peak values of a certain intensity at Landes g factors of 1.99 and 2.03, indicating that vacancy-controlled zinc cadmium sulfide has cadmium vacancies, while the pure phase zinc cadmium sulfide does not have peak values at Landes g factors of 1.99 and 2.03, indicating that the pure phase zinc cadmium sulfide does not have cadmium vacancies.
[0037] Figure 3 This is a comparison diagram of electron paramagnetic resonance between the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and pure phase zinc cadmium sulfide.
[0038] (iv) Electrochemical impedance spectroscopy was performed on the zinc cadmium sulfide catalyst with vacancy-controlled structure prepared in Example 1 of the present invention and pure zinc cadmium sulfide. It can be seen that the impedance arc radius of zinc cadmium sulfide with vacancy-controlled structure is smaller than that of pure zinc cadmium sulfide, indicating that zinc cadmium sulfide with vacancy-controlled structure has a faster charge transfer rate.
[0039] Figure 4 This is a comparison diagram of the electrochemical impedance spectroscopy between the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and pure phase zinc cadmium sulfide.
[0040] (V) Photoluminescence tests were performed on the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and the pure phase zinc cadmium sulfide. It can be seen that the fluorescence intensity of the vacancy-controlled zinc cadmium sulfide is less than that of the pure phase zinc cadmium sulfide. This indicates that the vacancy-controlled zinc cadmium sulfide can effectively suppress the recombination process of photogenerated electrons and holes, promote the migration rate of charge carriers, and thus improve the photocatalytic activity.
[0041] Figure 5 This is a comparison of the photoluminescence of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and pure phase zinc cadmium sulfide.
[0042] (vi) The photocurrent response test was performed on the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and the pure phase zinc cadmium sulfide. It can be seen that under the same light intensity, the pure phase zinc cadmium sulfide exhibits a lower photocurrent intensity, while the transient photocurrent intensity of the vacancy-controlled zinc cadmium sulfide is significantly enhanced, indicating that the vacancy-controlled zinc cadmium sulfide has better photosensitivity and a faster photogenerated electron transfer rate.
[0043] Figure 6 This is a comparison diagram of the photocurrent response of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and pure phase zinc cadmium sulfide.
[0044] (vii) Hydrogen production tests were conducted on the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of this invention and on pure-phase zinc cadmium sulfide. It was observed that the average hydrogen production rate of pure-phase zinc cadmium sulfide was 8.52 mmol g. -1 h -1 The average hydrogen production rate of the vacancy-controlled zinc cadmium sulfide catalyst was 27.17 mmol g. -1 h -1 .
[0045] Figure 7 This is a comparison chart of the hydrogen production rates of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention and pure phase zinc cadmium sulfide.
[0046] (viii) Hydrogen production cycle test was conducted on the zinc cadmium sulfide catalyst with vacancy control prepared in Example 1 of the present invention. It can be seen that the zinc cadmium sulfide catalyst with vacancy control exhibited good catalytic activity in a continuous cycle test of 30 hours and a total of 5 cycles.
[0047] Figure 8 This is a hydrogen production cycle test diagram of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention.
[0048] (ix) X-ray diffraction tests were performed on the zinc cadmium sulfide catalyst with vacancy-controlled hydrogen production cycle test prepared in Example 1 of the present invention before and after the hydrogen production cycle test. It can be seen that the X-ray diffraction of the zinc cadmium sulfide catalyst with vacancy-controlled hydrogen production cycle test before and after the test is highly consistent, indicating that it has good structural stability.
[0049] Figure 9 The X-ray diffraction patterns of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of this invention before and after cycle testing are shown.
[0050] (x) The preparation process of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention uses zinc acetate, cadmium chloride, thiourea, polyvinylpyrrolidone and hydrazine hydrate solution as raw materials and adopts a hydrothermal synthesis method.
[0051] Figure 10 This is a flowchart illustrating the preparation process of the vacancy-controlled zinc cadmium sulfide catalyst prepared in Example 1 of the present invention.
[0052] In summary, this embodiment successfully prepared a vacancy-controlled zinc cadmium sulfide catalyst using a one-step hydrothermal method with zinc acetate, cadmium chloride, thiourea, polyvinylpyrrolidone, and hydrazine hydrate solution as reaction raw materials. The catalyst exhibits good catalytic activity and structural stability.
Claims
1. Preparation of cadmium vacancy-regulated zinc cadmium sulfide catalyst, the preparation method includes the following steps: (1) Weigh 1.08g of zinc acetate, 1.14g of cadmium chloride, 0.38g of thiourea and 0.45g of polyvinylpyrrolidone, and add them together to 36mL of deionized water. Stir at a stable stirring speed for 15 minutes at room temperature to fully dissolve and mix the raw materials to form a homogeneous reaction solution. Then add 2mL of 40% hydrazine hydrate solution to the solution. (2) The above solution was subjected to ultrasonic treatment for 30 minutes to further promote the dispersion and mixing between molecules and enhance the uniformity of the reaction system. After ultrasonic treatment, the solution was divided into three equal parts and transferred to three 20 mL reaction vessels to ensure that the amount of reactants in each reaction vessel was consistent. (3) Place the reaction vessel containing the reaction solution into a forced-air drying oven set at 220°C and maintain the temperature for 24 hours to allow the reaction to proceed fully. After the reaction is completed, allow the sample to cool naturally to room temperature to avoid the impact of sudden temperature changes on the product structure. (4) After cooling, the sample was washed three times with deionized water and anhydrous ethanol to remove any impurities and unreacted raw materials that may remain on the sample surface. After washing, the precipitate was collected by centrifugation and a yellow precipitate was obtained. The precipitate was then dried in a forced-air drying oven at 60°C for 24 hours to remove the moisture and finally obtain the cadmium vacancy-controlled zinc cadmium sulfide catalyst material.
2. The application of the cadmium vacancy-regulated zinc cadmium sulfide catalyst prepared by the method of claim 1, characterized in that, Cadmium vacancy-regulated zinc cadmium sulfide catalysts are applied in the field of photocatalytic water-to-hydrogen production.
3. The preparation of the cadmium vacancy-regulated zinc-cadmium sulfide catalyst according to claim 1, characterized in that... In step 1, weigh out 1.08g of zinc acetate, 1.14g of cadmium chloride, 0.38g of thiourea, and 0.45g of polyvinylpyrrolidone.
4. The preparation of the cadmium vacancy-regulated zinc-cadmium sulfide catalyst according to claim 1, characterized in that... The ultrasound time mentioned in step 2 is set to 30 minutes.
5. The preparation of the cadmium vacancy-regulated zinc cadmium sulfide catalyst according to claim 1, characterized in that... The forced-air drying oven set at 220°C as described in step 3.
6. The preparation of the cadmium vacancy-regulated zinc-cadmium sulfide catalyst according to claim 1, characterized in that... Dry in a forced-air drying oven at 60°C for 24 hours as described in step 4.
7. The application of the cadmium vacancy-regulated zinc-cadmium sulfide catalyst according to claim 1, characterized in that, The application method is as follows: Take 5 mg of cadmium vacancy-controlled zinc cadmium sulfide and add it to 20 mL of deionized water containing a mixture of 0.25 mol sodium sulfite and 0.35 mol sodium sulfide. After ultrasonic treatment to form a uniform suspension, transfer it to a 30 mL reactor. Immediately use a vacuum pump to purge the air from the reactor, and simultaneously turn on the cooling water and stirrer. Check and ensure the airtightness of the apparatus. Place a 500W xenon lamp equipped with a cutoff filter on the side of the reactor and begin the illumination experiment. During the experiment, 200 μL of gas is extracted from the reactor every hour and injected into a GC9800 gas chromatograph to determine and record the hydrogen content. The results show that the hydrogen production rate of this cadmium vacancy-controlled zinc cadmium sulfide catalyst can reach 27.17 mmol g. -1 h -1 In addition, the catalyst was subjected to a continuous cycle test lasting 30 hours and a total of 5 cycles. During the 5 cycles, the catalyst showed good stability, and its photocatalytic hydrogen production performance did not significantly decrease after the cycle test, providing a strong guarantee of stability for its practical application.