A ZIF-derived zinc-cadmium sulfur photocatalyst, its preparation method and application

Abstract

A ZIF-derived zinc-cadmium sulfide photocatalyst, its preparation method, and its application are disclosed. The catalyst, by molar fraction, comprises: 35-50% 2-methylimidazole; 0-7.7% divalent cadmium ion compound; 0-7.7% divalent zinc ion compound; 7-10% thioacetamide; and 35-50% amines. The preparation method involves: preparing a 2-methylimidazole solution and a cadmium-zinc mixed solution separately; then preparing a ZIF precursor solution with cadmium and zinc as the central metals; adding thioacetamide to the precursor solution; transferring the solution to a polytetrafluoroethylene liner and hydrothermally treating it; finally collecting the hydrothermally treated solution, centrifuging, washing, drying, and grinding to obtain the ZIF-derived zinc-cadmium sulfide photocatalyst. The catalyst prepared by this invention has a large specific surface area and exhibits significant catalytic effects in photocatalytic water splitting for hydrogen production. Furthermore, the catalyst has a stable structure and can be recycled for a long period without a significant decrease in the hydrogen production rate.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic nanomaterial preparation and photocatalytic water splitting for hydrogen production technology, and specifically relates to a ZIF-derived zinc-cadmium sulfur photocatalyst, its preparation method and application. Background Technology

[0002] Hydrogen energy is a highly promising green and clean high-energy source. Mainstream green hydrogen production methods include photocatalytic water splitting, electrocatalytic water splitting, and photoelectrocatalysis. Photocatalytic water splitting uses solar energy to drive a semiconductor-based photocatalyst to generate photogenerated holes and electrons. The electrons' reducing power is then used to reduce protons in the water to produce hydrogen. This provides a promising and sustainable paradigm for solar energy utilization technology and has become a hot research topic in recent years.

[0003] Currently, the efficiency of photocatalytic water splitting for hydrogen production still falls short of the economic standards for large-scale application. The main limiting factors include the performance of photocatalyst materials, reaction conditions, and the structural design of the photocatalytic reaction device. Among these, modifying the photocatalyst and developing efficient and stable novel catalysts are key to improving the efficiency of photocatalytic water splitting for hydrogen production. The separation and transport of photogenerated electrons and holes during the reaction process play a crucial role in the activity of the photocatalyst and the reaction temperature. Therefore, it is necessary to rationally design the structure and surface of the materials to develop efficient and stable photocatalysts. In recent years, some novel catalysts such as TiO2, C3N4, and CdZnS have been extensively studied. However, they still suffer from low efficiency and poor stability, requiring further improvement. This means that the field of photocatalytic water splitting still faces many challenges.

[0004] However, current CdZnS photocatalysts generally have some problems: such as the high photogenerated electron-hole recombination rate of cadmium-sulfur photocatalysts, which may lead to relatively low photocatalytic activity; cadmium-sulfur photocatalysts may exhibit photocorrosion under certain circumstances, resulting in poor cycle stability and short service life.

[0005] Recently, Professor Hao Xuqiang's research group proposed in Applied Catalysis B: Environment and Energy 357(2024)124313 that a method of combining CdZnS with MXene (Mo2TiC2) can be used to improve the photocatalytic decomposition rate. Utilizing the terminal groups on the surface of MXene (Mo2TiC2) as active and adsorption sites, the electron transport distance is shortened, promoting the separation of photogenerated electrons and holes, thereby enhancing the hydrogen evolution capacity. This resulted in a photocatalytic activity of up to 17.73 mmol / h for 25% Mo2TiC2 / CdZnS. -1 g -1 However, this method has high overall cost and a long preparation cycle. Summary of the Invention

[0006] To overcome the shortcomings of the existing technology, the present invention aims to provide a ZIF-derived zinc-cadmium sulfur photocatalyst, its preparation method, and its application, by constructing a Cd... 2+ and Zn 2+ Bimetallic organic frameworks (MOFs) coordinated with organic ligands are used as precursors, which are then sulfided to prepare ZIF-derived CdZnS photocatalysts. Taking advantage of their regular morphology, large specific surface area, and adjustable size, the contact area between the catalyst and the reactants is increased, the separation of photogenerated electrons and holes is improved, and the efficiency of hydrogen evolution reaction is further enhanced, thus achieving high-efficiency hydrogen production.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] A ZIF-derived zinc-cadmium sulfur photocatalyst, comprising the following raw materials:

[0009] 2-Methylimidazole, with a molar fraction of 35-50%;

[0010] Divalent cadmium ion compounds, with a molar fraction of 0-7.7%;

[0011] Divalent zinc ion compounds, with a molar fraction of 0-7.7%;

[0012] Thioacetamide, with a molar fraction of 7-10%;

[0013] Amines, with a molar fraction of 35-50%.

[0014] The amines include any one of aniline, benzylamine, or oleylamine.

[0015] The divalent cadmium ion compound includes cadmium acetate dihydrate and cadmium chloride dihydrate; preferably cadmium acetate dihydrate.

[0016] The divalent zinc ion compound includes zinc acetate dihydrate and zinc chloride dihydrate; zinc acetate dihydrate is preferred.

[0017] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0018] Step 1: Weigh 35-50% 2-methylimidazole and dissolve it in deionized water to obtain a 2-methylimidazole solution.

[0019] Step 2: Weigh out divalent cadmium ion compound and divalent zinc ion compound with a molar fraction of 0-7.7% respectively, dissolve them in deionized water to obtain divalent cadmium ion compound solution and divalent zinc ion compound solution respectively, and mix the two to prepare cadmium-zinc mixed solution;

[0020] Step 3: Slowly add the cadmium-zinc mixed solution obtained in Step 2 to the 2-methylimidazole solution prepared in Step 1, and then add an amine substance with a molar fraction of 35-50% to it. The reaction yields a ZIF precursor solution with cadmium and zinc as the central metals.

[0021] Step 4: Weigh out 7-10% thioacetamide and add it to the precursor solution prepared in step 3.

[0022] Step 5: Transfer the solution obtained in Step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment;

[0023] Step 6: Collect the solution after hydrothermal treatment in step 5, centrifuge, wash and dry it, and then grind it to obtain the ZIF-derived zinc cadmium sulfur photocatalyst.

[0024] The concentration of the 2-methylimidazole solution obtained in step 1 is 0.34-0.48 mol / L. -1 .

[0025] In step 2, the concentrations of both the divalent cadmium ion compound solution and the divalent zinc ion compound solution are 0-0.075 mol / L. -1 .

[0026] In step 3, the cadmium-zinc mixed solution obtained in step 2 is used with 20 μL s -1 -30μL s -1 The solution was slowly added dropwise to the 2-methylimidazole solution obtained in step 1, followed by the slow addition of an amine as a ZIF size regulator, at a rotation speed of 700-900 rpm. -1 Stir the reaction for 4-6 hours to obtain the precursor solution.

[0027] In step 4, thioacetamide is slowly added to the precursor solution obtained in step 3, and the mixture is stirred for 13-20 minutes.

[0028] The hydrothermal reaction in step 5 is carried out at a temperature of 90-160℃ for 16-24 hours.

[0029] The centrifugation, washing, and drying process in step 6 specifically involves centrifuging the solution after hydrothermal treatment in step 5 at a speed of 8000-12000 r / min for 5-10 min. Then, the product is collected and ultrasonically dispersed and washed 2-3 times each with deionized water and anhydrous ethanol. The washed product is then vacuum dried at 60-80℃ for 10-12 h, and finally, the product is ground into powder.

[0030] The ZIF-derived zinc-cadmium sulfur photocatalyst prepared according to the above-described photocatalyst preparation method is applied by loading noble metal materials onto the surface of the ZIF-derived zinc-cadmium sulfur photocatalyst to construct a heterojunction, thereby enhancing the electron-hole separation efficiency and improving the photocatalytic hydrogen production performance; the noble metal materials include Pt and Ru.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. In the specific operation of the preparation method of the ZIF-derived zinc-cadmium sulfur photocatalyst described in this invention, Zn is used... 2+ and Cd 2+ As a metal center, 2-methylimidazolium is used as an organic ligand to form MOF precursors. By using the regular porous structure of MOFs as the catalyst framework, the long transport path effectively improves the electron-hole separation efficiency, and the large specific surface area can provide more reaction sites to promote the reaction. Then, thioacetamide is used to sulfide to form ZIF-derived CdZnS photocatalyst to optimize the structure and carrier transport performance of the thio-zinc-cadmium photocatalyst.

[0033] 2. In the actual operation of preparing this catalyst, the ratio of cadmium ions to zinc ions and the amount of amine substances added as MOF size regulators can be flexibly controlled. The addition of amine regulators not only regulates the size of MOFs, but also provides a weakly alkaline atmosphere for the reaction environment, so as to achieve the expected optimal photocatalytic hydrogen production activity and excellent cycle stability.

[0034] 3. Further heterojunctions can be constructed by loading materials onto the catalyst surface to enhance electron-hole separation efficiency, such as by depositing noble metals like Pt and Ru, thereby exhibiting better photocatalytic hydrogen production performance. It also has extremely high application potential and value in photocatalytic reactors with very low catalyst usage, such as photocatalytic microchannel reactors.

[0035] In summary, this invention constructs Cd 2+ and Zn 2+ Bimetallic organic frameworks (MOFs) coordinated with organic ligands were used as precursors, followed by sulfidation to prepare ZIF-derived CdZnS photocatalysts. Utilizing their regular morphology, large specific surface area, and adjustable size, the contact area between the catalyst and reactants was increased. The addition of amine modifiers not only regulated the size of the MOFs but also provided a weakly alkaline atmosphere for the reaction, effectively solving the instability problem of sulfur-zinc-cadmium catalysts. This improved the separation of photogenerated electrons and holes, further enhancing the efficiency of the hydrogen evolution reaction. Attached Figure Description

[0036] Figure 1 The image shows the XRD pattern of the material synthesized in this invention.

[0037] Figure 2 TEM image of the material synthesized in this invention;

[0038] Figure 3a The graphs show the hydrogen production performance of Examples 1-5;

[0039] Figure 3b The hydrogen production performance diagrams for Examples 6 and 7 are shown.

[0040] Figure 3c The hydrogen production performance diagrams for Examples 8-10 are shown.

[0041] Figure 4 0.5 wt% Pt-Cd prepared in Example 8 of this invention 0.33 Zn 0.67 S-PhA hydrogen production cycle performance diagram. Detailed Implementation

[0042] To clearly illustrate the content of this invention, the following examples provide a more detailed description of the invention. However, the scope of protection of this invention is not limited to the content described. All chemical reagents used in the examples are of analytical grade.

[0043] Example 1

[0044] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0045] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0046] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0047] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0048] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0049] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0050] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-PhA.

[0051] The Cd obtained by weighing 0.33 Zn 0.67 5 mg of S-PhA photocatalyst was dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution in a 40 ml side-illuminated quartz window container. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and controlled temperature of 35 °C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting rate for hydrogen production was 38.592 mmol / h within 3 h. -1 g -1 See Figure 3.

[0052] Figure 2 The TEM image of the Cd0.33Zn0.67S-PhA catalyst prepared in Example 1 shows that the catalyst has a morphology of dispersed nanoparticles on a tetrahedral matrix. The large specific surface area provides more reaction sites for the reaction, which also provides theoretical proof for improving hydrogen production performance.

[0053] Example 2

[0054] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0055] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0056] Step 2: Weigh 1.5 mmol of cadmium acetate dihydrate and dissolve it in 20 ml of deionized water to obtain a concentration of 0.075 mol / L. -1 Cadmium acetate dihydrate solution;

[0057] Step 3: Dissolve the solution obtained in Step 2 in 25 μL s -1The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium as the central metal.

[0058] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0059] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0060] Step 6: Collect the solution after hydrothermal treatment in step 5, centrifuge it at a speed of 10000 r / min for 5 min, then collect the product, and wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product, vacuum dry it at 60℃ for 12 h, and grind the final product into powder to obtain the ZIF-derived photocatalyst CdS-PhA.

[0061] 5 mg of the obtained CdS-PhA photocatalyst was weighed into a 40 ml side-illuminated quartz window container and dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and temperature control at 35 °C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting to hydrogen production rate was 8.572 mmol / h within 3 h. -1 g -1 ,See Figure 3a .

[0062] Example 3

[0063] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0064] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0065] Step 2: Weigh 1.0 mmol of cadmium acetate dihydrate and 0.5 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.05 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.025 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0066] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0067] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0068] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0069] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.67 Zn 0.33 S-PhA.

[0070] The Cd obtained by weighing 0.67 Zn 0.33 5 mg of S-PhA photocatalyst was dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution in a 40 ml side-illuminated quartz window container. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and temperature control at 35°C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting rate for hydrogen production was 4.478 mmol / h within 3 h. -1 g -1 ,See Figure 3a .

[0071] Example 4

[0072] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0073] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0074] Step 2: Weigh 0.75 mmol of cadmium acetate dihydrate and 0.75 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.0375 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.0375 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0075] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0076] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0077] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0078] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.5 Zn 0.5 S-PhA.

[0079] The Cd obtained by weighing 0.5 Zn 0.5 5 mg of S-PhA photocatalyst was dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution in a 40 ml side-illuminated quartz window container. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and controlled temperature of 35 °C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting rate for hydrogen production was 23.674 mmol / h within 3 h. -1 g -1 ,See Figure 3a .

[0080] Example 5

[0081] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0082] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0083] Step 2: Weigh 1.5 mmol of zinc acetate dihydrate and dissolve it in 20 ml of deionized water to obtain a concentration of 0.075 mol / L. -1 Zinc acetate dihydrate solution;

[0084] Step 3: Dissolve the solution obtained in Step 2 in 25 μL s -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0085] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0086] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0087] Step 6: Collect the solution after hydrothermal treatment in step 5, centrifuge it at a speed of 10000 r / min for 5 min, then collect the product, and wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product, vacuum dry it at 60℃ for 12 h, and grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst ZnS-PhA.

[0088] 5 mg of the obtained ZnS-PhA photocatalyst was weighed into a 40 ml side-illuminated quartz window container and dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and temperature control at 35 °C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting hydrogen production rate was 4.568 mmol / h within 3 h. -1 g -1 ,See Figure 3a .

[0089] Figure 1The XRD patterns of the zinc-cadmium sulfur catalysts prepared in Examples 1-5 are in excellent agreement with the hexagonal phase of the CZS solid solution. No impurity flare peaks were detected in the XRD patterns, indicating that zinc-cadmium sulfur catalysts with high purity and crystallinity were prepared.

[0090] Example 6

[0091] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0092] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0093] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0094] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of benzylamine, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0095] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0096] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0097] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-BA.

[0098] The Cd obtained by weighing 0.33 Zn 0.675 mg of S-BA photocatalyst was dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution in a 40 ml side-illuminated quartz window container. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas Ar was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and controlled temperature of 35°C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting rate for hydrogen production was 4.392 mmol / h within 3 h. -1 g -1 ,See Figure 3b .

[0099] Example 7

[0100] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0101] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0102] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0103] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of oleylamine, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0104] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0105] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0106] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-YA.

[0107] The Cd obtained by weighing 0.33 Zn 0.67 5 mg of S-YA photocatalyst was dispersed in 20 ml of a 10% (v / v) lactic acid aqueous solution in a 40 ml side-illuminated quartz window container. The mixture was then sonicated for 10 min to ensure homogeneity. Inert gas (Ar) was then introduced for 15 min to purge the air from the container. The reaction was then carried out under stirring and controlled temperature of 35 °C. Samples were taken every 30 min for gas chromatography analysis. The photocatalytic water splitting rate for hydrogen production was 29.849 mmol / h within 3 h. -1 g -1 ,See Figure 3b .

[0108] Example 8

[0109] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0110] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0111] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0112] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0113] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0114] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0115] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-PhA.

[0116] The Cd obtained by weighing 0.33 Zn 0.67 100 mg of S-PhA photocatalyst was dispersed in 125 ml of a side-illuminated quartz window container in 120 ml of a 20% (v / v) methanol-water solution. Then, 0.5% (w / w) of Pt was added, followed by sonication for 10 min to ensure homogeneity. An inert gas (Ar) was then introduced for 15 min to purge the air from the container. The mixture was then irradiated with a 300 W xenon lamp under stirring for 1 h. Pt metal was deposited on the catalyst surface via hydrogen photoreduction. After the reaction, the reaction solution was collected, centrifuged, and washed three times each with deionized water and anhydrous ethanol. The solution was then vacuum-dried at 60 °C for 12 h. Finally, the solid catalyst was collected and ground to obtain a yellow-green 0.5 wt% Pt-Cd. 0.33 Zn 0.67 S-PhA; samples were taken every 30 minutes for gas chromatography detection, and the photocatalytic water splitting hydrogen production rate was 270.6 mmol / h within 3 hours. -1 g -1 ,See Figure 3c .

[0117] Example 9

[0118] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0119] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0120] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0121] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0122] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0123] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0124] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-PhA.

[0125] The Cd obtained by weighing 0.33 Zn 0.67 100 mg of S-PhA photocatalyst was dispersed in 125 ml of a side-illuminated quartz window container in 120 ml of a 20% (v / v) methanol-water solution. Then, 0.3% (w / w) of Pt was added, followed by sonication for 10 min to ensure homogeneity. An inert gas (Ar) was then introduced for 15 min to purge the air from the container. The mixture was then irradiated with a 300 W xenon lamp under stirring for 1 h. Pt metal was deposited on the catalyst surface via hydrogen photoreduction. After the reaction, the reaction solution was collected, centrifuged, and washed three times each with deionized water and anhydrous ethanol. The solution was then vacuum-dried at 60 °C for 12 h. Finally, the solid catalyst was collected and ground to obtain a yellow-green 0.3 wt% Pt-Cd. 0.33 Zn 0.67S-PhA; samples were taken every 30 minutes for gas chromatography detection, and the photocatalytic water splitting hydrogen production rate was 196.4 mmol / h within 3 hours. -1 g -1 ,See Figure 3c .

[0126] Example 10

[0127] A method for preparing a ZIF-derived zinc-cadmium sulfur photocatalyst specifically includes the following steps:

[0128] Step 1: Weigh 8 mmol of 2-methylimidazole and dissolve it in 20 ml of deionized water to obtain a concentration of 0.4 mol / L. -1 2-methylimidazole solution;

[0129] Step 2: Weigh 0.5 mmol of cadmium acetate dihydrate and 1.0 mmol of zinc acetate dihydrate, and dissolve them separately in 20 ml of deionized water to obtain a concentration of 0.025 mol / L. -1 Cadmium acetate dihydrate solution with a concentration of 0.05 mol / L -1 A zinc acetate dihydrate solution was mixed with the zinc acetate solution to prepare a cadmium-zinc mixed solution.

[0130] Step 3: Dissolve the cadmium-zinc mixed solution obtained in Step 2 in 25 μL solutions. -1 The solution was slowly added dropwise to the 2-methylimidazole solution prepared in step 1, followed by the addition of 8 mmol of aniline, and the mixture was stirred at a speed of 800 rpm. -1 The reaction was stirred for 4 hours to obtain a ZIF precursor solution with cadmium and zinc as the central metals.

[0131] Step 4: Weigh 1.875 mmol of thioacetamide and add it to the precursor solution prepared in step 3. Stir the reaction for 15 min.

[0132] Step 5: Transfer the solution obtained in step 4 into a polytetrafluoroethylene liner and perform hydrothermal treatment. The hydrothermal reaction temperature is 125℃ and the reaction time is 20h.

[0133] Step 6: Collect the solution after hydrothermal treatment in Step 5, centrifuge at 10000 r / min for 5 min, then collect the product. Wash it three times each with deionized water and anhydrous ethanol using ultrasonic dispersion. Collect the washed product and vacuum dry it at 60℃ for 12 h. Grind the final product into powder to obtain the ZIF-derived zinc cadmium sulfur photocatalyst Cd. 0.33 Zn 0.67 S-PhA.

[0134] The Cd obtained by weighing 0.33 Zn 0.67100 mg of S-PhA photocatalyst was dispersed in 125 ml of a side-illuminated quartz window container in 120 ml of a 20% (v / v) methanol-water solution. Then, 1.0% (w / w) of Pt was added, followed by sonication for 10 min to ensure homogeneity. An inert gas (Ar) was then introduced for 15 min to purge the air from the container. The mixture was then irradiated with a 300 W xenon lamp under stirring for 1 h. Pt metal was deposited on the catalyst surface via hydrogen photoreduction. After the reaction, the reaction solution was collected, centrifuged, and washed three times each with deionized water and anhydrous ethanol. The solution was then vacuum-dried at 60 °C for 12 h. Finally, the solid catalyst was collected and ground to obtain a yellow-green 1.0 wt% Pt-Cd. 0.33 Zn 0.67 S-PhA; samples were taken every 30 minutes for gas chromatography detection. The photocatalytic water splitting hydrogen production rate within 3 hours was 223.4 mmol / h. -1 g -1 ,See Figure 3c .

[0135] The above embodiments show that the ZIF-derived zinc-cadmium sulfur photocatalyst of the present invention has a significant optimization effect on hydrogen production from water under mild photocatalytic water splitting.

[0136] Example 11

[0137] Catalyst stability tests were performed on the system of Example 8. The system was cycled every 3 hours for a total of 12 hours. After one cycle, the reaction was stopped, and 10 vol% lactic acid was added. The system was then purged with Ar for 15 minutes, followed by photoreaction. The results are as follows: Figure 4 As shown, it was found that the hydrogen production rate did not change significantly after four cycles, proving that the material of the present invention has good hydrogen production efficiency and excellent stability.

[0138] As can be seen from the above embodiments, compared with the prior art, the present invention constructs a ZIF precursor to derive CdZnS, thereby increasing the specific surface area of ​​the photocatalyst and improving the reaction contact area, thus greatly improving the hydrogen production performance of photocatalytic water splitting. Figure 3a It can be seen that adjusting the cadmium to zinc ratio (1:0, 2:1, 1:1, 1:2, 0:1) corresponds to a hydrogen production rate of 8.572 mmol / h. -1 g -1 4.478 mmol h -1 g -1 23.674 mmol h -1 g -1 38.592 mmol h -1 g -1 4.568 mmol h -1 g -1;Cd prepared in Example 1 0.33 Zn 0.67 S-PhA exhibits higher hydrogen production performance than directly synthesized CdZnS nanomaterials (6.122 mmol h). -1 g -1 ),Depend on Figure 3c It can be seen that in the synthesized Cd 0.33 Zn 0.67 Loading different amounts of Pt onto the S-PhA surface significantly improved its performance, with the 0.5 wt% Pt-Cd prepared in Example 8 showing the best results. 0.33 Zn 0.67 The S-PhA catalyst exhibits a hydrogen production performance as high as 270.6 mmol / h. -1 g -1 This represents the highest performance reported to date, providing a feasible strategy for the practical application of photocatalytic water splitting to produce hydrogen. Furthermore, the material exhibited excellent stability, with no performance degradation in hydrogen production during four cycles of testing. The nanomaterial synthesis method described in this invention is simple, the reaction conditions are mild, and the photocatalytic water splitting hydrogen production performance is significantly improved compared to existing technologies.

Claims

1. Use of a ZIF-derived sulfurized zinc cadmium photocatalyst in photocatalytic hydrogen production, characterized in that, The preparation method of the sulfur zinc cadmium photocatalyst comprises the following steps: Step 1, 2-methylimidazole with a mass fraction of 35-50% is weighed, and deionized water is used for dissolving treatment to prepare a 2-methylimidazole solution; Step 2, divalent cadmium ion compound and divalent zinc ion compound with a mass fraction of 0-7.7% and not zero are respectively weighed, and deionized water is used for dissolving to obtain a divalent cadmium ion compound solution and a divalent zinc ion compound solution, and the two are mixed to prepare a cadmium zinc mixed solution; the divalent cadmium ion compound is cadmium acetate dihydrate, and the divalent zinc ion compound is zinc acetate dihydrate; wherein the molar amount of the cadmium acetate dihydrate is 0.5 mmol, and the molar amount of the zinc acetate dihydrate is 1 mmol, or the molar amount of the cadmium acetate dihydrate is 0.75 mmol, and the molar amount of the zinc acetate dihydrate is 0.75 mmol; Step 3, the cadmium zinc mixed solution obtained in step 2 is slowly added into the 2-methylimidazole solution prepared in step 1, and then an amine substance with a mass fraction of 35-50% is added, and a ZIF precursor solution with cadmium and zinc as central metals is obtained; the amine substance is aniline or oleylamine; Step 4, thioacetamide with a mass fraction of 7-10% is weighed and added into the precursor solution prepared in step 3; Step 5, the solution obtained in step 4 is transferred into a polytetrafluoroethylene liner and subjected to hydrothermal treatment; Step 6, the solution after the hydrothermal treatment in step 5 is collected, centrifuged, washed and dried, and then ground to obtain a ZIF-derived sulfur zinc cadmium photocatalyst.

2. Use of the ZIF-derived zinc cadmium sulfide photocatalyst according to claim 1 for photocatalytic hydrogen production, characterized in that, The concentration of the 2-methylimidazole solution prepared in the step 1 is 0.34-0.48 mol / L -1 ; the concentration of the divalent cadmium ion compound solution and the divalent zinc ion compound solution in the step 2 is 0-0.075 mol / L -1 , and is not zero.

3. Use of the ZIF-derived zinc cadmium sulfide photocatalyst according to claim 1 in photocatalytic hydrogen production, characterized in that, The cadmium-zinc mixed solution prepared in Step 2 is slowly added to 20 μL s -1 -30 μL s -1 of the 2-methylimidazole solution obtained in Step 1 at a rate of 0.5 mL / min, followed by slow addition of the amine as a ZIF size regulator at a rate of 0.5 mL / min. The reaction is stirred at a rate of 700-900 r / min -1 for 4-6 h to obtain a precursor solution.

4. Use of the ZIF-derived zinc cadmium sulfide photocatalyst according to claim 1 in photocatalytic hydrogen production, characterized in that, In step 4, after slowly adding thioacetamide into the precursor solution prepared in step 3, stirring reaction is carried out for 13-20 min.

5. Use of the ZIF-derived zinc cadmium sulfide photocatalyst according to claim 1 in photocatalytic hydrogen production, characterized in that, In step 5, the temperature of the hydrothermal reaction is 90-160 DEG C, and the reaction time is 16-24 h.

6. Use of the ZIF-derived zinc cadmium sulfide photocatalyst according to claim 1 in photocatalytic hydrogen production, characterized in that, In step 6, the centrifugal washing and drying are specifically as follows: the solution after the hydrothermal treatment in step 5 is centrifuged at a speed of 8000-12000 r / min for 5-10 min, then the product is collected, and deionized water and anhydrous ethanol are used for ultrasonic dispersion washing for 2-3 times respectively, the washed product is collected, and vacuum drying is carried out at a temperature of 60-80 DEG C for 10-12 h, and finally the product is ground into powder.

7. Use of the ZIF-derived cadmium zinc sulfide photocatalyst according to any one of claims 1 to 6 for photocatalytic hydrogen production, characterized in that, The ZIF-derived sulfur zinc cadmium photocatalyst is loaded with noble metal materials to construct a heterojunction, so that the electron hole separation efficiency is enhanced, and the photocatalytic hydrogen production performance is improved; the noble metal materials include Pt and Ru.

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