Composite visible-light-driven photocatalyst as well as preparation and application thereof
Through Ni, Co bimetal doping and ZIF-8 coating technology, the photocatalytic activity and stability of CdS are improved, the problems of low catalytic reaction activity and inability to regulate the H2/CO ratio are solved, and efficient CO2 reduction and synthesis gas regulation are achieved.
Patent Information
- Application Number
- CN202311561754.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-05-23
AI Technical Summary
When CdS is used to photocatalyze the reduction of CO2 and H2O to syngas, the catalytic reaction activity is low, the product H2/CO ratio cannot be regulated, and the photochemical stability is poor.
By doping CdS with Ni and Co bimetallic elements and wrapping ZIF-8 on the surface of doped CdS, a heterostructure is constructed to improve photogenerating and migration of photogenerated carriers and increase catalytic activity and photochemical stability.
The activity of catalytic CO2 and H2O reduction reactions is improved, and the H2/CO ratio in the synthesis gas can be regulated and photochemical stability is maintained.
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Figure CN120022947A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photocatalysts, and in particular to a composite visible light catalyst and its preparation and application. Background Art
[0002] As the amount of fossil energy consumed by human industrial production and daily life increases, the amount of CO in the atmosphere 2 The rising concentration has caused a series of energy and environmental problems. Therefore, it is urgent to develop technologies that can reduce atmospheric CO 2 Sustainable and green conversion technology for CO 2 and H 2 O reduction to synthesis gas technology has the characteristics of clean and green reaction process, and does not require additional fossil energy to drive the reaction process, so it plays an important role in achieving "carbon neutrality" and CO 2 It has broad application prospects in resource utilization. Synthesis gas is composed of H 2 and CO. Synthesis gas can be used in industrial production to produce methanol, diesel and other hydrocarbon products. However, the required synthesis gas contains H 2 / CO ratio is different (Angew. Chem. Int. Ed., 2016, 55, 14262-14266; Nat. Catal., 2020, 3: 843-850.). Therefore, it is necessary to develop a method that can adjust the H content in the photocatalytic reduction reaction product. 2 / CO ratio of the catalyst, thereby further improving the utilization value of the process and broadening the application range of the reaction products.
[0003] Cadmium sulfide (CdS) has the advantages of being cheap, readily available, and having a stable structure. Its band gap is about 2.4 eV, so it can absorb visible light and has a suitable 2 The conduction band position of CO is reduced to that of CdS, so CdS is very suitable for CO 2 Semiconductor photocatalytic materials that selectively reduce to CO. However, the photogenerated carrier lifetime of CdS is short and the photogenerated carrier recombination rate is fast, which makes its photocatalytic activity weak and prone to photocorrosion; in addition, the surface of CdS lacks catalytic reaction sites, which is not conducive to CO 2 Adsorption and activation not only seriously limit the CdS photocatalytic CO 2 and H 2 O reduction reaction efficiency, and in the photocatalytic CO 2 and H 2 O reduction to produce synthesis gas cannot control the H 2 / CO ratio. Summary of the invention
[0004] In order to solve the problem of CdS photocatalytic CO2 and H 2 O reduction to produce synthesis gas has low catalytic activity and the product H 2 In order to solve the problems that the ratio of / CO cannot be adjusted and the photochemical stability is poor, the present invention aims to provide a composite visible light catalyst and its preparation and application.
[0005] The present invention can construct a heterogeneous structure on the surface of CdS to promote the generation and migration of photogenerated carriers, and can also be used as a catalyst for CO 2 and H 2 O reduction reaction active sites, effectively improving CdS catalytic CO 2 and H 2 O reduction reaction catalytic activity; metal organic frameworks (MOFs) have rich and adjustable pore structure and ultra-high specific surface area, rich functional sites and other characteristics make them popular in catalysis, gas adsorption, drug delivery and other fields, especially ZIF-8 as a classic MOFs structure with mild preparation conditions and stable chemical properties. By wrapping ZIF-8 on the surface of doped CdS to prepare a composite material, on the one hand, the specific surface area of the composite material can be increased, thereby improving the photocatalytic CO 2 On the other hand, the activity of the reduction reaction can also inhibit the photocorrosion of CdS and improve the photochemical stability of the composite material.
[0006] The purpose of the present invention can be achieved by the following technical solutions:
[0007] The first object of the present invention is to provide a method for preparing a composite visible light photocatalyst, comprising the following steps:
[0008] (S1) cadmium salt, nickel salt, cobalt salt, thiourea and polyvinyl pyrrolidone are dissolved and mixed, and then reacted, and then post-treated to obtain Ni and Co bimetallic doped CdS;
[0009] (S2) dispersing the Ni, Co bimetallic doped CdS prepared in step (S1) and mixing it with 2-methylimidazole and zinc nitrate in sequence, and then post-treating it to obtain a composite photocatalyst.
[0010] In one embodiment of the present invention, in step (S1), the molar ratio of the cadmium salt to thiourea is 1:10-50, the molar ratio of the cadmium salt to the nickel salt is 2-8:1, the molar ratio of the nickel salt to the cobalt salt is 3:1-1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 10-30:1.
[0011] In one embodiment of the present invention, the molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 6:1, the molar ratio of the nickel salt to the cobalt salt is 1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:6.
[0012] In one embodiment of the present invention, the molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 2:1, the molar ratio of the nickel salt to the cobalt salt is 3:1, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:6.
[0013] In one embodiment of the present invention, the cadmium salt is selected from one or more of cadmium nitrate, cadmium sulfate, cadmium acetate or cadmium chloride;
[0014] The nickel salt is selected from one or more of nickel nitrate, nickel sulfate, nickel acetate or nickel chloride;
[0015] The cobalt salt is selected from one or more of cobalt nitrate, cobalt sulfate, cobalt acetate or cobalt chloride.
[0016] In one embodiment of the present invention, in step (S1), during the reaction, the temperature is 120 to 150° C. and the time is 2 to 8 hours;
[0017] Preferably, during the reaction, the temperature is 135-145° C. and the reaction time is 3-7 hours.
[0018] In one embodiment of the present invention, in step (S1), the post-treatment is cooling to room temperature after the reaction, separating the solid by centrifugation, washing with ethanol and distilled water for several times, and vacuum drying.
[0019] In one embodiment of the present invention, in step (S2), the mass ratio of Ni, Co bimetallic doped CdS, 2-methylimidazole and zinc nitrate is 1:5-20:5-25.
[0020] In one embodiment of the present invention, in step (S2), Ni, Co bimetallic doped CdS is dispersed in methanol, and the usage ratio of Ni, Co bimetallic doped CdS to methanol is 1 mg: 1-5 mL.
[0021] In one embodiment of the present invention, in step (S2), the post-treatment is to centrifuge and discard the supernatant, wash the precipitate with ethanol and distilled water for several times respectively, and then dry it in vacuum.
[0022] The second object of the present invention is to provide a composite visible light photocatalyst prepared by the above method.
[0023] The third object of the present invention is to provide a composite visible light catalyst for photocatalytic CO 2 and H 2 The application of O reduction in the reaction of producing synthesis gas comprises the following steps:
[0024] (A1) dissolving the composite visible light photocatalyst in water and mixing it with an electron sacrificial agent to obtain a mixed solution;
[0025] (A2) placing the mixed solution prepared in step (A1) in a closed CO 2 In a saturated atmosphere, the catalytic CO 2 and H 2 O reduction to produce synthesis gas.
[0026] In one embodiment of the present invention, in step (A1), in the mixed solution, the concentration of the composite visible light catalyst is 0.01-0.1 mg / mL; the concentration of the electron sacrificial agent is 0.5-1.5 mol / L.
[0027] In one embodiment of the present invention, the electron sacrificial agent is selected from one of triethylamine and triethanolamine.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] The preparation method of the composite visible light photocatalyst provided by the present invention is to prepare Ni and Co bimetallic doped CdS by utilizing the difference in solubility product constants (K sp,NiS ≈K sp,CoS >K sp,CdS ) has realized the construction of heterostructure on the CdS surface, which can promote the generation and migration of photogenerated carriers, thereby improving the catalytic activity of the reaction. At the same time, different Ni and Co element doping ratios can be used to control the H content in the reaction product synthesis gas. 2 / CO ratio; using ZIF-8 to coat Ni, Co bimetallic element doped CdS can utilize the higher specific surface area and stability of ZIF-8 to make the obtained composite visible light catalyst have a higher specific surface area and improve the photochemical stability of the composite photocatalyst.
[0030] Therefore, the composite visible light photocatalyst obtained by the present invention can efficiently catalyze CO under visible light irradiation. 2 and H 2 O reduction to produce synthesis gas, and the H content in the product synthesis gas can be regulated 2 / CO ratio and maintain photochemical stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is a SEM image of the composite photocatalyst prepared in Example 1;
[0032] Figure 2 TEM image of the composite photocatalyst prepared in Example 1;
[0033] Figure 3 This is the XRD pattern of the composite photocatalyst prepared in Example 1;
[0034] Figure 4The photocatalytic activity results of the composite photocatalyst prepared in Example 1 after four recycling cycles. DETAILED DESCRIPTION
[0035] The present invention provides a method for preparing a composite visible light catalyst, comprising the following steps:
[0036] (S1) cadmium salt, nickel salt, cobalt salt, thiourea and polyvinyl pyrrolidone are dissolved and mixed, and then reacted, and then post-treated to obtain Ni and Co bimetallic doped CdS;
[0037] (S2) dispersing the Ni, Co bimetallic doped CdS prepared in step (S1) and mixing it with 2-methylimidazole and zinc nitrate in sequence, and then post-treating to obtain a composite photocatalyst.
[0038] Furthermore, in step (S1), the molar ratio of the cadmium salt to thiourea is 1:10-50, the molar ratio of the cadmium salt to the nickel salt is 2-8:1, the molar ratio of the nickel salt to the cobalt salt is 3:1-1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 10-30:1.
[0039] Furthermore, the molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 6:1, the molar ratio of the nickel salt to the cobalt salt is 1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:6.
[0040] Furthermore, the molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 2:1, the molar ratio of the nickel salt to the cobalt salt is 3:1, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:6.
[0041] Further, the cadmium salt is selected from one or more of cadmium nitrate, cadmium sulfate, cadmium acetate or cadmium chloride;
[0042] The nickel salt is selected from one or more of nickel nitrate, nickel sulfate, nickel acetate or nickel chloride;
[0043] The cobalt salt is selected from one or more of cobalt nitrate, cobalt sulfate, cobalt acetate or cobalt chloride.
[0044] Furthermore, in step (S1), during the reaction, the temperature is 120 to 150° C. and the time is 2 to 8 hours;
[0045] Preferably, during the reaction, the temperature is 135-145° C. and the reaction time is 3-7 hours.
[0046] Furthermore, in step (S1), the post-treatment is cooling to room temperature after the reaction, separating the solid by centrifugation, washing with ethanol and distilled water for several times, and vacuum drying.
[0047] Furthermore, in step (S2), the mass ratio of Ni, Co bimetallic doped CdS, 2-methylimidazole and zinc nitrate is 1:5-20:5-25.
[0048] Furthermore, in step (S2), Ni, Co bimetallic doped CdS is dispersed in methanol, and the usage ratio of Ni, Co bimetallic doped CdS to methanol is 1 mg: 1-5 mL.
[0049] Furthermore, in step (S2), the post-treatment is to centrifuge and discard the supernatant, wash the precipitate with ethanol and distilled water for several times respectively, and then vacuum dry it.
[0050] The invention provides a composite visible light catalyst prepared by the method.
[0051] The present invention provides a composite visible light catalyst for photocatalytic CO 2 and H 2 The application of O reduction in the reaction of producing synthesis gas comprises the following steps:
[0052] (A1) dissolving the composite visible light photocatalyst in water and mixing it with an electron sacrificial agent to obtain a mixed solution;
[0053] (A2) placing the mixed solution prepared in step (A1) in a closed CO 2 In a saturated atmosphere, the catalytic CO 2 and H 2 O reduction to produce synthesis gas.
[0054] Furthermore, in step (A1), in the mixed solution, the concentration of the composite visible light catalyst is 0.01-0.1 mg / mL; and the concentration of the electron sacrificial agent is 0.5-1.5 mol / L.
[0055] Furthermore, the electron sacrificial agent is selected from one of triethylamine and triethanolamine.
[0056] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
[0057] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.
[0058] Example 1
[0059] (1) Preparation of Ni, Co bimetallic doped CdS: 0.69 g (3 mmol) cadmium acetate, 0.27 g (1.5 mmol) nickel acetate, 0.27 g (1.5 mmol) cobalt acetate, 3.0 g (40.0 mmol) thiourea, 0.06 g polyvinyl pyrrolidone and 75 mL distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 140°C for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and stored in a vacuum dryer.
[0060] (2) Preparation of ZIF-8-wrapped Ni, Co bimetallic doped CdS composite visible light photocatalyst: 5 mg Ni, Co bimetallic doped CdS was dispersed in 20 mL methanol, and then 49 mg 2-methylimidazole was added and ultrasonically dispersed for 30 minutes. Then, 45 mg zinc nitrate methanol solution was added to the dispersion and ultrasonicated for 5 minutes. The dispersion was kept in the dark for 3 hours. The solid nanoparticles were separated by centrifugation, washed with ethanol and distilled water several times, and vacuum dried to obtain a composite visible light photocatalyst (the SEM image of which is shown in FIG. 2 ). Figure 1 As shown in the TEM image Figure 2 As shown, the XRD pattern is Figure 3 shown).
[0061] Composite visible light photocatalyst for CO catalysis 2 and H 2 O reduction to synthesis gas reaction: 1 mg of composite visible light photocatalyst was added into 20 mL of deionized water, and then 20 mmol of electron sacrificial agent triethanolamine was added. After ultrasonic dispersion, mixed solution A was obtained. The mixed solution A was transferred to a photocatalytic reaction bottle, the air in the system was removed, and CO was introduced into the solution. 2 The gas was saturated, the system was sealed, and a 300W xenon lamp (equipped with a >400nm filter) was used as a visible light source to irradiate the photocatalytic reaction bottle for catalytic reaction at room temperature. The results are shown in Table 1.
[0062] The photocatalytic activity of the composite photocatalyst prepared in this example after recycling and using it four times is shown in FIG. Figure 4 As shown, through Figure 4 It can be found that the composite photocatalyst prepared in this example can still maintain its original catalytic activity after five recycling cycle catalytic experiments, proving that it can maintain photochemical stability.
[0063] Example 2
[0064] Except that in step (1), 0.69 g (3 mmol) of cadmium acetate, 0.27 g (1.5 mmol) of nickel acetate, 0.089 g (0.5 mmol) of cobalt acetate, 3.0 g (40.0 mmol) of thiourea, 0.06 g of polyvinyl pyrrolidone and 75 mL of distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 145° C. for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps were the same as those in Example 1.
[0065] Example 3
[0066] Except that in step (1), 0.69 g (3 mmol) of cadmium acetate, 0.088 g (0.5 mmol) of nickel acetate, 0.27 g (1.5 mmol) of cobalt acetate, 3.0 g (40.0 mmol) of thiourea, 0.06 g of polyvinyl pyrrolidone and 75 mL of distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 145° C. for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps were the same as those in Example 1.
[0067] Example 4
[0068] Except that in step (1), 0.69 g (3 mmol) of cadmium acetate, 0.27 g (1.5 mmol) of nickel acetate, 0.13 g (0.75 mmol) of cobalt acetate, 3.0 g (40.0 mmol) of thiourea, 0.06 g of polyvinyl pyrrolidone and 75 mL of distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 140° C. for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps were the same as those in Example 1.
[0069] Example 5
[0070] Except that in step (1), 0.69 g (3 mmol) of cadmium acetate, 0.13 g (0.75 mmol) of nickel acetate, 0.27 g (1.5 mmol) of cobalt acetate, 3.0 g (40.0 mmol) of thiourea, 0.06 g of polyvinyl pyrrolidone and 75 mL of distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 140° C. for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps were the same as those in Example 1.
[0071] Example 6
[0072] Except that in step (2), 5 mg of Ni, Co bimetallic doped CdS was dispersed in 20 mL of methanol, 75 mg of 2-methylimidazole was added and ultrasonically dispersed for 45 minutes, 45 mg of zinc nitrate methanol solution was added to the dispersion and ultrasonicated for 5 minutes, and the dispersion was kept in dark for 3 hours. Solid nanoparticles were separated by centrifugation, washed with ethanol and distilled water several times, and vacuum dried to obtain a composite visible light photocatalyst. The other steps were the same as those in Example 1.
[0073] Example 7
[0074] Except that in step (2), 5 mg of Ni, Co bimetallic doped CdS was dispersed in 20 mL of methanol, 49 mg of 2-methylimidazole was added and ultrasonically dispersed for 30 minutes, 100 mg of zinc nitrate methanol solution was added to the dispersion and ultrasonicated for 10 minutes, and the dispersion was kept in dark for 3 hours. The solid nanoparticles were separated by centrifugation, washed with ethanol and distilled water several times, and vacuum dried to obtain a composite visible light photocatalyst. The other steps were the same as those in Example 1.
[0075] Example 8
[0076] Except that in step (1), 0.55 g (3 mmol) of cadmium chloride, 0.19 g (1.5 mmol) of nickel chloride, 0.20 g (1.5 mmol) of cobalt chloride, 6.1 g (80.0 mmol) of thiourea and 0.05 g of polyvinyl pyrrolidone were dissolved and 75 mL of distilled water were added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 140° C. for 6 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps were the same as those in Example 1.
[0077] Example 9
[0078] Except that in step (1), 0.71 g (3 mmol) of cadmium nitrate, 0.27 g (1.5 mmol) of nickel nitrate, 0.27 g (1.5 mmol) of cobalt nitrate, 7.6 g (100.0 mmol) of thiourea and 0.07 g of polyvinyl pyrrolidone are dissolved and 75 mL of distilled water is added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 135° C. for 4 hours. After the reaction solution is cooled to room temperature, the solid nanoparticles are separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps are the same as those in Example 1.
[0079] Example 10
[0080] Except that in step (1), 0.63 g (3 mmol) of cadmium sulfate, 0.23 g (1.5 mmol) of nickel sulfate, 0.23 g (1.5 mmol) of cobalt sulfate, 7.6 g (100.0 mmol) of thiourea and 0.06 g of polyvinyl pyrrolidone are dissolved and 75 mL of distilled water is added to a 100 mL hydrothermal kettle, stirred at room temperature until completely dissolved, and reacted at 145° C. for 3 hours. After the reaction solution is cooled to room temperature, the solid nanoparticles are separated by centrifugation, washed several times with ethanol and water respectively, and vacuum dried for storage. The other steps are the same as those in Example 1.
[0081] Comparative Example 1
[0082] Preparation of CdS photocatalyst: 0.69g cadmium acetate, 3.0g thiourea and 0.06g polyvinyl pyrrolidone were dissolved and added into 100mL hydrothermal kettle with 75mL distilled water, stirred at room temperature until completely dissolved, and reacted at 140℃ for 4 hours. After the reaction solution was cooled to room temperature, solid nanoparticles were separated by centrifugation, washed with ethanol and water several times respectively, and vacuum dried for storage. The CdS photocatalyst was obtained.
[0083] CdS photocatalyst for CO catalysis 2 and H 2 O reduction to produce synthesis gas reaction: 1 mg CdS photocatalyst was added to 20 mL deionized water, and then 20 mmol of electron sacrificial agent triethanolamine was added. After ultrasonic dispersion, mixed solution A was obtained. The mixed solution A was transferred to a photocatalytic reaction bottle, the air in the system was removed, and CO was introduced into the solution. 2 The gas was saturated, the system was sealed, and a 300W xenon lamp (equipped with a >400nm filter) was used as a visible light source to irradiate the photocatalytic reaction bottle for catalytic reaction at room temperature. The results are shown in Table 1.
[0084] Table 1 Specific surface area and photocatalytic reaction results of the composite visible light catalysts of Examples 1 to 10 and Comparative Example 1
[0085]
[0086] As shown in Table 1, the composite visible light photocatalyst obtained in the present invention exhibits a larger specific surface area and a higher catalytic CO 2 The results of Examples 1 to 5 show that different doping ratios of Ni and Co bimetallic elements can achieve the reduction of H in the reaction product synthesis gas. 2 The regulation of the CO / CO ratio between 1:0.26 and 3.4 is beneficial to the further industrial application of the reaction products.
[0087] Depend on Figures 1 to 3It can be seen that Example 1 completes the preparation of the composite visible light photocatalyst, and the crystal structure of the product is the same as that of the standard substance. It can be confirmed that Ni and Co bimetallic doped CdS is synthesized and ZIF-8 is successfully wrapped on its surface.
[0088] In summary, the preparation method of the composite visible light photocatalyst provided by the present invention is to prepare a bimetallic element doped CdS with a Ni and Co element ratio, by utilizing the difference in the solubility product constant of metal sulfides (K sp,NiS ≈K sp,CoS >K sp,CdS ) has realized the construction of heterostructures on the CdS surface, which can promote the generation and migration of photogenerated carriers, thereby improving the catalytic activity of the reaction and regulating the H in the reaction product by using different doping ratios of Ni and Co bimetallic elements. 2 / CO ratio, using ZIF-8 to coat the bimetallic element doped CdS, the higher specific surface area and stability of ZIF-8 can be utilized to make the resulting composite photocatalyst have a higher specific surface area and improve the photochemical stability of the composite photocatalyst.
[0089] The above embodiments are only some specific cases, but the composite visible light photocatalyst can be prepared by the preparation method of the composite visible light photocatalyst of the present invention within the following conditions:
[0090] In step (1), the molar ratio of the cadmium salt to thiourea is 1:10-50, the molar ratio of the cadmium salt to the nickel salt is 2-8:1, the molar ratio of the nickel salt to the cobalt salt is 3:1-1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 10-30:1.
[0091] In step (1), during the reaction, the temperature is 120-150° C. and the reaction time is 2-8 h;
[0092] In step (2), the mass ratio of Ni, Co bimetallic doped CdS, 2-methylimidazole and zinc nitrate is 1:5-20:5-25.
[0093] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the explanation of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.
Claims
1. A method for preparing a composite visible light photocatalyst, It is characterized in that The following steps are involved: (S1) cadmium salt, nickel salt, cobalt salt, thiourea and polyvinyl pyrrolidone are dissolved and mixed, and then reacted, and then post-treated to obtain Ni and Co bimetallic doped CdS; (S2) dispersing the Ni, Co bimetallic doped CdS prepared in step (S1) and mixing it with 2-methylimidazole and zinc nitrate in sequence, and then post-treating it to obtain a composite photocatalyst.
2. The method for preparing a composite visible light photocatalyst according to claim 1, It is characterized in that In step (S1), the molar ratio of the cadmium salt to thiourea is 1:10-50, the molar ratio of the cadmium salt to the nickel salt is 2-8:1, the molar ratio of the nickel salt to the cobalt salt is 3:1-1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 10-30:
1.
3. The method for preparing a composite visible light photocatalyst according to claim 2, It is characterized in that The molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 6:1, the molar ratio of the nickel salt to the cobalt salt is 1:3, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:
6.
4. The method for preparing a composite visible light photocatalyst according to claim 2, It is characterized in that The molar ratio of the cadmium salt to thiourea is 3:40, the molar ratio of the cadmium salt to the nickel salt is 2:1, the molar ratio of the nickel salt to the cobalt salt is 3:1, and the mass ratio of the cadmium salt to polyvinyl pyrrolidone is 69:
6.
5. The method for preparing a composite visible light photocatalyst according to claim 1, It is characterized in that The cadmium salt is selected from one or more of cadmium nitrate, cadmium sulfate, cadmium acetate or cadmium chloride; The nickel salt is selected from one or more of nickel nitrate, nickel sulfate, nickel acetate or nickel chloride; The cobalt salt is selected from one or more of cobalt nitrate, cobalt sulfate, cobalt acetate or cobalt chloride.
6. The method for preparing a composite visible light photocatalyst according to claim 1, It is characterized in that In step (S1), during the reaction, the temperature is 120-150° C. and the reaction time is 2-8 hours.
7. The method for preparing a composite visible light photocatalyst according to claim 1, It is characterized in that In step (S2), the mass ratio of Ni, Co bimetallic doped CdS, 2-methylimidazole and zinc nitrate is 1:5-20:5-25.
8. A composite visible light photocatalyst prepared by the method according to any one of claims 1 to 7.
9. A composite visible light photocatalyst as claimed in claim 8 for photocatalytic CO 2 and H 2 Application of O reduction to synthesis gas reaction, It is characterized in that The following steps are involved: (A1) dissolving the composite visible light photocatalyst according to claim 7 in water and mixing it with an electron sacrificial agent to obtain a mixed solution; (A2) placing the mixed solution prepared in step (A1) in a closed CO 2 In a saturated atmosphere, the catalytic CO 2 and H 2 O reduction to produce synthesis gas.
10. The composite visible light photocatalyst according to claim 9 for photocatalytic CO 2 and H 2 Application of O reduction to synthesis gas reaction, It is characterized in that In step (A1), in the mixed solution, the concentration of the composite visible light photocatalyst is 0.01-0.1 mg / mL; the concentration of the electron sacrificial agent is 0.5-1.5 mol / L; The electron sacrificial agent is selected from triethylamine or triethanolamine.