Preparation method of hollow spherical bimetallic oxide cluster photocatalyst

Abstract

The invention relates to a preparation method of a hollow spherical bimetallic oxide cluster photocatalyst, and belongs to the field of preparation of inorganic nano materials. The method comprises the following steps: dissolving dichloro-metallocene and polyacid in a solvent to obtain a precursor solution; adding alkali liquor to adjust the pH after stirring for the first time; stirring for the second time, transferring into a polytetrafluoroethylene lining, and sealing in a stainless steel high-pressure reaction kettle; and putting the mixture into a drying oven to react at a set temperature, and after the reaction is finished, carrying out centrifugal washing and drying to obtain the hollow spherical bimetallic oxide cluster photocatalyst. According to the preparation method, the precursor structure is regulated and controlled through step-by-step stirring and pH regulation by utilizing the dynamic difference between metallocene dichloride and polyacid hydrolysis, and a hollow spherical structure is formed through hydrothermal treatment. The obtained product is large in specific surface area, active sites are fully exposed, the bimetal components synergistically enhance light absorption and carrier separation efficiency, and the product shows high activity, high selectivity and good stability in photocatalytic CO2 reduction.

Description

Technical Field

[0001] This invention relates to the field of inorganic nanomaterial preparation technology, specifically to a method for preparing a hollow spherical bimetallic oxide cluster photocatalyst. Background Technology

[0002] Photocatalytic reduction of carbon dioxide (CO2) technology can directly utilize solar energy to drive the reaction and shows significant application potential in converting CO2 into high-value-added chemicals (such as carbon monoxide, methane, formic acid, etc.), making it one of the research hotspots in the field of photocatalysis.

[0003] In the photocatalytic reduction of CO2, light absorption and charge generation, charge separation and migration, and surface catalytic reactions are three core stages that collectively constrain the improvement of overall catalytic efficiency. However, existing photocatalytic materials still suffer from several technical shortcomings in these stages: First, traditional single-component metal oxides (such as titanium dioxide and zinc oxide) have large band gaps and narrow visible light absorption ranges, making it difficult to efficiently capture the most abundant visible light portion of sunlight, resulting in low efficiency in the light absorption and charge generation processes. Second, due to their continuous and dense material structure, traditional bulk catalysts have long transport paths for photogenerated charge carriers to migrate from the material interior to the surface, leading to rapid recombination of electron-hole pairs within the bulk phase, significantly reducing the effective charge carrier utilization rate and severely restricting the charge separation and migration processes. Furthermore, the limited specific surface area of ​​solid-structure materials results in insufficient exposure of active sites, making it difficult for reactant molecules to effectively contact the catalytic surface, thereby inhibiting the efficiency of surface catalytic reactions. These problems are interconnected, and a single strategy cannot simultaneously overcome them.

[0004] To address the aforementioned technical challenges, researchers have attempted improvements through strategies such as morphology control and component composites. For example, constructing hollow structures can shorten carrier transport distances and increase specific surface area; introducing bimetallic components can modulate band structure and enhance light absorption. However, existing preparation methods still struggle to simultaneously achieve precise morphology control and uniform cluster dispersion, especially when using organometallic compounds as raw materials. The hydrolysis rate is difficult to coordinately control, easily leading to structural collapse or component segregation, thus limiting further improvements in material performance. Therefore, developing a photocatalyst preparation method capable of precisely constructing hollow spherical structures and achieving uniform dispersion of bimetallic components is of great significance for improving CO2 photocatalytic reduction efficiency. Summary of the Invention

[0005] In order to solve the problems of the prior art, the present invention provides a method for preparing hollow spherical bimetallic oxide cluster photocatalysts.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: First aspect: A method for preparing a hollow spherical bimetallic oxide cluster photocatalyst, characterized by comprising the following steps: S1, dissolve dichlorodicyclopentene and polyacid in a solvent to obtain a precursor solution; S2, After stirring the precursor solution prepared in step S1 for the first time, add alkaline solution to adjust the pH; S3, the mixed solution in step S2 is stirred for a second time, then transferred to a polytetrafluoroethylene liner and sealed in a stainless steel high-pressure reactor; S4. Place the stainless steel high-pressure reactor from step S3 in an oven and react at a set temperature. After the reaction is complete, centrifuge and wash the product, and then dry it to obtain a hollow spherical bimetallic oxide cluster photocatalyst.

[0007] In one specific embodiment of the first aspect, the amount of dichlorodicyclopentene used in step S1 is 1~100 mg, the amount of polyacid is 1~100 mg, and the amount of solvent is 5~50 mL.

[0008] In one specific embodiment of the first aspect, the alkaline solution in step S2 is an aqueous solution of NaOH or ammonia, with a volume of 0.1 to 3 mL and a concentration of 5 to 30 wt.%.

[0009] In one specific embodiment of the first aspect, the dichlorodicenocene metal in step S1 is selected from one of dichlorodicenocene zirconium, dichlorodicenocene titanium, and dichlorodicenocene hafnium; the polyacid is selected from one of phosphotungstic acid, phosphomolybdic acid, and undecyltungstencobalt indium acid; and the solvent used is one of ethanol, acetone, or a mixture of ethanol and acetone.

[0010] In one specific embodiment of the first aspect, the stirring speed in step S2 is 500~2000 r / min, and the stirring time is 10~120 min.

[0011] In one specific embodiment of the first aspect, the stirring speed in step S3 is 1000~3000 r / min, and the stirring time is 10~60 min.

[0012] In one specific embodiment of the first aspect, the reaction conditions in step S4 are: reacting at 150~220°C for 6~24 h.

[0013] In one specific embodiment of the first aspect, the centrifugal washing in step S4 is performed at a speed of 9000~12000 r / min, the centrifugation time is 2~10 min, and the washing reagent is ethanol; the drying conditions are drying in a vacuum environment at 60°C for 6~24 h.

[0014] Secondly, a hollow spherical bimetallic oxide cluster photocatalyst is prepared by a method, wherein the size of the cluster is 50~1000 nm.

[0015] In one specific embodiment of the second aspect, the application of hollow spherical bimetallic oxide cluster photocatalysts in photocatalytic CO2 reduction.

[0016] The present invention provides a method for preparing hollow spherical bimetallic oxide cluster photocatalysts, using dichlorodicyclopentene and polyacids as raw materials. A precursor is constructed by controlling the difference in hydrolysis kinetics between the two: the two raw materials are dissolved in a weakly acidic solvent. Due to the high hydrolysis constant and fast rate of the metal ions in dichlorodicyclopentene, they preferentially react with OH-. - The process involves the formation of primary hydroxide particles. Heteropolyanions generated from the dissociation of polyacids are electrostatically adsorbed onto the particle surface, forming a "hydroxide-polyacid" composite core. After adjusting the pH with dilute ammonia and continuing stirring, metal ions with slower hydrolysis rates from the polyacid dissociation gradually migrate towards the composite core and deposit as a thin layer of hydroxide on its outer surface. This precursor is then transferred to a reactor for hydrothermal reaction. Under high temperature and pressure, the polyacid in the middle layer dissociates and dissolves in the hydrothermal liquid phase; the inner and outer hydroxide layers simultaneously dehydrate and oxidize to oxides, ultimately forming hollow spherical bimetallic oxide clusters.

[0017] The preparation method provided by this invention can significantly improve the controllability of material morphology, greatly increase the specific surface area, and promote the exposure of catalytic active sites. The synthesized hollow spherical bimetallic oxide cluster photocatalyst has significantly better photocatalytic performance than uncomposite dichlorodicenocene and polyacids, and has broad application prospects and important significance in the field of carbon dioxide reduction.

[0018] The beneficial effects of this invention are as follows: 1. This invention utilizes the difference in hydrolysis kinetics between dichlorodicyclopentene and polyacids as raw materials, combined with stepwise stirring and pH adjustment processes, to achieve precise control over the precursor structure. During the reaction, the faster-hydrolyzing metallocene preferentially forms hydroxide cores, while polyacid anions are electrostatically adsorbed and coated onto the surface. Subsequently, hydrothermal treatment causes the middle layer polyacid to dissociate and the inner and outer layers of hydroxides to simultaneously dehydrate and oxidize, thereby precisely constructing a bimetallic oxide cluster with a hollow spherical structure. This hollow structure effectively increases the specific surface area of ​​the material, significantly shortens the carrier transport path, suppresses electron-hole recombination, and promotes the full exposure of active sites, solving the key technical problems of low mass transfer efficiency and insufficient active sites in traditional bulk catalysts.

[0019] 2. The hollow spherical bimetallic oxide cluster photocatalyst prepared by the method of this invention effectively modulates the band structure through the synergistic effect of the bimetallic components, broadens the visible light response range, and enhances light absorption capacity and charge separation efficiency. As shown in the examples, this catalyst exhibits excellent catalytic activity, high selectivity, and good cycling stability in the photocatalytic CO2 reduction reaction, providing a new, efficient, and controllable preparation route for the application of photocatalytic materials in environmental governance and energy conversion, and has broad prospects for industrial application. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope (SEM) image of the hollow spherical bimetallic oxide cluster photocatalyst in Example 1 of this application.

[0021] Figure 2 This is a test diagram of the photocatalytic performance of the hollow spherical bimetallic oxide cluster photocatalyst in Example 1 of this application.

[0022] Figure 3 This is a scanning electron microscope (SEM) image of the hollow spherical bimetallic oxide cluster photocatalyst in Example 2 of this application.

[0023] Figure 4 This is a test diagram of the photocatalytic performance of the hollow spherical bimetallic oxide cluster photocatalyst in Example 2 of this application.

[0024] Figure 5 This is a scanning electron microscope (SEM) image of the hollow spherical bimetallic oxide cluster photocatalyst in Example 3 of this application.

[0025] Figure 6 This is a test diagram of the photocatalytic performance of the hollow spherical bimetallic oxide cluster photocatalyst in Example 3 of this application. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figures 1 to 6 This paper presents a method for preparing a hollow spherical bimetallic oxide cluster photocatalyst.

[0028] This invention provides a method for preparing hollow spherical bimetallic oxide cluster photocatalysts, comprising the following steps: S1 dissolves dichlorodicyclopentene and polyacids in a solvent; S2 is the precursor solution prepared in step S1, which is stirred for the first time and then ammonia is added; The mixed solution in step S2 in step S3 is stirred for a second time, and then transferred to a polytetrafluoroethylene liner, which is then sealed in a stainless steel high-pressure reactor. S4. The stainless steel high-pressure reactor from step S3 is placed in an oven and reacted at a set temperature. After obtaining the product, it is centrifuged and washed three times, and then dried to obtain a hollow spherical bimetallic oxide cluster photocatalyst.

[0029] This invention provides a method for preparing hollow spherical bimetallic oxide cluster photocatalysts, which first involves dissolving raw materials dichlorodicenocene and polyacids in a solvent to obtain a precursor solution.

[0030] In this invention, the preferred mass of the dichlorodicyclopentene is 1-100 mg, more preferably 10-50 mg; the preferred mass of the polyacid is 1-100 mg, more preferably 10-50 mg; the preferred amount of the solvent is 5-50 mL, more preferably 5-20 mL; the preferred amount of NaOH aqueous solution or ammonia water is 0.1-3 mL, with a concentration of 5-30 wt.%, more preferably 0.1-1 mL, with a concentration of 15-30 wt.%; the preferred dichlorodicyclopentene is one of zirconium dichlorodicyclopentene, titanium dichlorodicyclopentene, and hafnium dichlorodicyclopentene; the preferred polyacid is one of phosphotungstic acid, phosphomolybdic acid, and undecyltungstencobalt indium acid; the preferred solvent is one of ethanol, acetone, and a mixture of ethanol and acetone.

[0031] In this invention, the raw materials are thoroughly mixed through stirring during the reaction process, ensuring efficient reaction in a homogeneous system. Simultaneously, ammonia is used to regulate the pH value of the solvent within the reaction system. The introduction of ammonia not only effectively regulates the hydrolysis rate of the raw materials, enabling controllability of the intermediate formation process, but also forms a synergistic guiding effect with the solvent, significantly promoting the interaction between metallocene cation hydroxides and polyacid cation hydroxides, driving the formation of stable coordination bonds between them, thereby initially forming a spherical structure, achieving a larger specific surface area and faster mass transport, and greatly enhancing photocatalytic performance.

[0032] In this invention, the first stirring speed is preferably 500-2000 r / min, more preferably 800-1500 r / min, and the time is preferably 10-120 min, more preferably 10-60 min; the amount of NaOH aqueous solution or ammonia water is 0.1-3 mL, the concentration is 5-30 wt.%, more preferably 0.1-1 mL, and the concentration is 15-30 wt.%; the second stirring speed is preferably 1000-3000 r / min, more preferably 1200-2000 r / min, and the time is preferably 10-60 min, more preferably 20-40 min.

[0033] After completing the stirring hydrolysis process, the precursor solution is subjected to high-temperature and high-pressure treatment to obtain a hollow spherical bimetallic oxide cluster photocatalyst. In this invention, the high-temperature and high-pressure treatment is preferably hydrothermal treatment. The hydrothermal treatment and subsequent processing include the following steps: placing a stainless steel high-pressure reactor containing the precursor solution into an oven, reacting at a set temperature, centrifuging and washing the product three times, and then drying to obtain the hollow spherical bimetallic oxide cluster photocatalyst.

[0034] In this invention, the preferred temperature for the hydrothermal reaction is 150~220°C. o C, more preferably 160~200 o C; the preferred time is 6~24 h, more preferably 12~24 h. Under high temperature and high pressure, the middle layer polyacids dissociate and dissolve in the hydrothermal liquid; the inner and outer layer hydroxides simultaneously dehydrate and oxidize to oxides, thus obtaining hollow spherical bimetallic oxide clusters. In the subsequent centrifugal drying process, the preferred centrifugal speed is 9000~12000 r / min, more preferably 9000~10000 r / min, the preferred centrifugation time is 2~10 min, more preferably 3~8 min, and the drying conditions are 60 o In a vacuum environment of C, the drying time is preferably 6 to 24 hours, more preferably 6 to 12 hours.

[0035] This invention also provides the application of the hollow spherical bimetallic oxide cluster photocatalyst described in the above-mentioned technical solution in photocatalytic CO2 reduction. Preferably, the photocatalyst provided by this invention is used for photocatalytic CO2 reduction under gas-solid reaction conditions. Specifically, a high-transmittance quartz reactor is used as the photocatalytic reactor, and a calibrated, uniformly intense xenon lamp is used to simulate sunlight. The photocatalyst is weighed and uniformly dispersed at the bottom of a quartz reactor containing deionized water, ultrasonicated, and dried overnight. After this, a uniformly distributed catalyst film is obtained at the bottom of the photoreactor. Then, to ensure complete removal of air from the reactor, a mixture of H2O vapor and high-purity CO2 is continuously introduced into the quartz reactor. After the gas introduction operation is completed, the quartz photoreactor is quickly sealed, and the quartz reactor filled with the H2O vapor and high-purity CO2 mixture is placed under a xenon lamp to simulate the full spectrum of sunlight for irradiation. Circulating cooling water is used to maintain the reaction temperature. Online gas chromatography is used for qualitative and quantitative analysis of the reaction gas composition.

[0036] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Example 1

[0037] CO2 reduction performance test of hollow spherical bimetallic oxide cluster photocatalyst: S1 dissolves 25 mg of zirconium dichlorophenocene and 26 mg of phosphotungstic acid in 8 mL of acetone; S2. Stir the precursor solution prepared in step S1 at 1000 r / min for 10 min, then add 0.35 mL of ammonia water; S3 Continue stirring the mixed solution from step S2 at 1500 r / min for 30 min, then transfer it to a polytetrafluoroethylene liner and seal the liner in a stainless steel high-pressure reactor. S4 Place the stainless steel high-pressure reactor from step S3 into an oven at 200°C. o The reaction was carried out at C for 12 h. After obtaining the product, it was washed three times by centrifugation with ethanol at 10000 r / min for 2 min, and then at 60 °C. o Spherical zirconium dichlorodichloro-zirconia-phosphotungstic acid photocatalysts were prepared by vacuum drying of C, and characterized by SEM (see [link]). Figure 1 ); S5. 10 mg of the zirconium dichlorodichloropentanoate-phosphotungstic acid photocatalyst obtained in step S4 was uniformly dispersed at the bottom of a quartz reactor containing 15 mL of deionized water, and heated at 60 °C. oAfter being dried overnight in an oven at C, a uniformly distributed catalyst film was obtained at the bottom of the photoreactor. The quartz reactor was a high-transmittance quartz reactor with a volume of 180 mL, which was used as the photocatalytic reactor. S6. The catalyst-containing photocatalytic reactor obtained in step S5 is continuously purged with a mixture of H2O vapor and high-purity CO2 for 30 minutes. The quartz reactor filled with the H2O vapor and high-purity CO2 mixture is then placed under a xenon lamp to simulate the full spectrum of sunlight. The reaction temperature is maintained at 15°C using circulating cooling water. o C. Qualitative and quantitative analysis of the composition of the reaction gases was performed using an online gas chromatograph (HF-901, Huifen Instruments Co., Ltd.), which yielded the following results: Figure 2 Performance test chart in the middle. Example 2

[0038] CO2 reduction performance test of hollow spherical bimetallic oxide cluster photocatalyst: S1 dissolves 20 mg of dichlorodicyclopentadiene and 30 mg of phosphomolybdic acid in 8 mL of a 1:1 mixture of ethanol and acetone. S2. Stir the precursor solution prepared in step S1 at 800 r / min for 40 min, then add 0.75 mL of ammonia water; S3 Continue stirring the mixed solution from step S2 at 1800 r / min for 60 min, then transfer it to a polytetrafluoroethylene liner and seal the liner in a stainless steel high-pressure reactor. S4 Place the stainless steel high-pressure reactor from step S3 into an oven at 180°C. o The reaction was carried out at C for 16 hours. After obtaining the product, it was washed three times by centrifugation with ethanol at 10000 r / min for 2 minutes, and then at 60 °C. o Spherical dichlorotitanthocene-phosphomolybdic acid photocatalysts were prepared by vacuum drying of C, and characterized by SEM (see [link]). Figure 3 ); S5. 20 mg of the dichlorodichlorotitanium-phosphomolybdic acid photocatalyst obtained in step S4 was uniformly dispersed at the bottom of a quartz reactor containing 20 ml of deionized water, and incubated at 60 °C. o After being dried overnight in an oven at C, a uniformly distributed catalyst film was obtained at the bottom of the photoreactor. The quartz reactor was a high-transmittance quartz reactor with a volume of 180 mL, which was used as the photocatalytic reactor. S6. The catalyst-containing photocatalytic reactor obtained in step S5 is continuously purged with a mixture of H2O vapor and high-purity CO2 for 30 minutes. The quartz reactor filled with the H2O vapor and high-purity CO2 mixture is then placed under a xenon lamp to simulate the full spectrum of sunlight. The reaction temperature is maintained at 15°C using circulating cooling water. oC. Qualitative and quantitative analysis of the composition of the reaction gases was performed using an online gas chromatograph (HF-901, Huifen Instruments Co., Ltd.), which yielded the following results: Figure 4 Performance test chart in the middle. Example 3

[0039] CO2 reduction performance test of hollow spherical bimetallic oxide cluster photocatalyst: S1 dissolves 30 mg of hafnium dichloroethylene and 40 mg of undecyltungsten cobalt indium acid in 10 mL of ethanol; S2. The precursor solution prepared in step S1 is stirred at 1500 r / min for 60 min, and 1 mL of NaOH aqueous solution (15 wt.%) is added. S3 Continue stirring the mixed solution from step S2 at 2000 r / min for 40 min, then transfer it to a polytetrafluoroethylene liner and seal the liner in a stainless steel high-pressure reactor. S4 Place the stainless steel high-pressure reactor from step S3 into an oven at 190°C. o The reaction was carried out at C for 12 h. After obtaining the product, it was washed three times by centrifugation with ethanol at 10000 r / min for 2 min, and then at 60 °C. o Spherical dichlorotitanium-phosphomolybdic acid photocatalyst was prepared by vacuum drying of C and characterized by SEM. S5. 10 mg of the hafnium dichlorodecane-undecaptenate-cobalt indium phosphate photocatalyst obtained in step S4 was uniformly dispersed at the bottom of a quartz reactor containing 10 ml of deionized water, and incubated at 60 °C. o After being dried overnight in an oven at C, a uniformly distributed catalyst film was obtained at the bottom of the photoreactor. The quartz reactor was a high-transmittance quartz reactor with a volume of 180 ml, which was used as the photocatalytic reactor. S6. The catalyst-containing photocatalytic reactor obtained in step S5 is continuously purged with a mixture of H2O vapor and high-purity CO2 for 30 minutes. The quartz reactor filled with the H2O vapor and high-purity CO2 mixture is then placed under a xenon lamp to simulate the full spectrum of sunlight. The reaction temperature is maintained at 15°C using circulating cooling water. o C. Qualitative and quantitative analysis of the composition of the reaction gases was performed using an online gas chromatograph (HF-901, Huifen Instruments Co., Ltd.), and performance test charts were obtained.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a hollow spherical bimetallic oxide cluster photocatalyst, characterized in that, Includes the following steps: S1, dissolve dichlorodicyclopentene and polyacid in a solvent to obtain a precursor solution; S2, After stirring the precursor solution prepared in step S1 for the first time, add alkaline solution to adjust the pH; S3, the mixed solution in step S2 is stirred for a second time, then transferred to a polytetrafluoroethylene liner and sealed in a stainless steel high-pressure reactor; S4. Place the stainless steel high-pressure reactor from step S3 in an oven and react at a set temperature. After the reaction is complete, centrifuge and wash the product, and then dry it to obtain a hollow spherical bimetallic oxide cluster photocatalyst.

2. The preparation method according to claim 1, characterized in that, In step S1, the amount of dichlorodicyclopentene is 1-100 mg, the amount of polyacid is 1-100 mg, and the amount of solvent is 5-50 mL.

3. The preparation method according to claim 1, characterized in that, The alkaline solution mentioned in step S2 is an aqueous solution of NaOH or ammonia, with a volume of 0.1 to 3 mL and a concentration of 5 to 30 wt.%.

4. The preparation method according to claim 1, characterized in that, The dichlorodicyclopentene metal mentioned in step S1 is selected from one of dichlorodicyclopentene zirconium, dichlorodicyclopentene titanium, and dichlorodicyclopentene hafnium; the polyacid is selected from one of phosphotungstic acid, phosphomolybdic acid, and undecyltungstencobalt indium acid; and the solvent used is one of ethanol, acetone, or a mixture of ethanol and acetone.

5. The preparation method according to claim 1, characterized in that, In step S2, the first stirring speed is 500~2000 r / min, and the stirring time is 10~120 min.

6. The preparation method according to claim 1, characterized in that, In step S3, the second stirring speed is 1000~3000 r / min, and the stirring time is 10~60 min.

7. The preparation method according to claim 1, characterized in that, The reaction conditions in step S4 are: react at 150~220°C for 6~24 h.

8. The preparation method according to claim 1, characterized in that, In step S4, the centrifugation speed is 9000~12000 r / min, the centrifugation time is 2~10 min, and the washing reagent is ethanol; the drying conditions are drying in a vacuum environment at 60°C for 6~24 h.

9. A hollow spherical bimetallic oxide cluster photocatalyst, characterized in that, The clusters are prepared by the method described in any one of claims 1 to 8, and the size of the clusters is 50 to 1000 nm.

10. The application of the hollow spherical bimetallic oxide cluster photocatalyst according to claim 9 in photocatalytic CO2 reduction.

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