A method for preparing a metal-kieselguhr carrier for use in electrocatalytic water splitting

Abstract

The present application relates to the carrier technology of inorganic catalyst, aiming at providing a preparation method of metal-kieselguhr carrier applied to electrocatalytic water decomposition. The method comprises: sieving and acid immersion treatment of kieselguhr; putting the acid immersion kieselguhr into deionized water, and carrying out ultrasonic dispersion treatment to obtain kieselguhr turbidity; then adding metal acetate solution, carrying out ultrasonic and stirring treatment after mixing; transferring the mixture into a hydrothermal kettle to carry out hydrothermal reaction, and carrying out filtration and cleaning of the solid after the reaction to obtain metal-kieselguhr used as a carrier. The kieselguhr carrier prepared by the present application has developed pore structure and large specific surface area, which is helpful to uniform dispersion of the catalyst, exposes more active sites, and thus improves the catalytic activity; the carrier can be used as part of the raw material of the supported catalyst, or directly used as the catalyst applied to electrocatalytic water decomposition; when applied to HER / OER, the carrier has lower overpotential, smaller Tafel slope, higher turnover frequency and better stability.

Description

Technical Field

[0001] This invention pertains to inorganic catalyst support technology, and particularly relates to a method for preparing a metal-diatomite support for electrocatalytic water splitting. Background Technology

[0002] To alleviate the increasingly severe energy shortage and environmental pollution problems, there is an urgent need to find new energy sources to replace carbon-based energy. Hydrogen, with its high energy density and lack of environmental pollution, is one of the best alternatives to fossil fuels. Electrocatalytic water splitting, with its high conversion efficiency, high hydrogen purity, and commercial value, is currently one of the best methods for hydrogen production. However, water splitting requires a high overpotential to overcome the slow kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). To improve the performance of electrocatalytic water splitting, current research mainly focuses on the development of novel catalysts, and new strategies are needed to further enhance catalytic performance.

[0003] Catalyst supports typically possess a large specific surface area, enabling uniform catalyst dispersion and effectively addressing catalyst agglomeration issues. This exposes more active sites, thereby improving catalytic efficiency. Catalyst supports can enhance metal atom utilization, reduce metal consumption, and lower costs. Furthermore, the interaction between the support and the catalyst can further improve catalyst stability and catalytic activity. Therefore, using suitable catalyst supports to load electrocatalysts can effectively improve the performance of electrocatalytic water splitting, and researchers in the field have proposed various types of electrocatalysts.

[0004] Currently, various supports have been applied to supported electrocatalysts. The most common supports are carbon supports, such as porous carbon nanotubes, graphene, and carbon nanotubes. However, carbon is unstable in OER processes under strong acidic or oxidizing environments and can be oxidized or participate in the reaction. Non-carbon supports such as metal oxides, carbides, and nitrides exhibit excellent durability and strong electronic interactions with the catalyst. However, the relatively high cost of these catalyst supports limits their large-scale application. Therefore, there is a need to develop more stable and inexpensive catalyst supports.

[0005] Diatomaceous earth, formed from the sedimentary remains of diatoms, is primarily composed of amorphous silica. As a natural mineral, it is abundant, inexpensive, and environmentally friendly. Diatomaceous earth possesses excellent chemical and thermal stability, as well as strong adsorption capacity. Its good hydrophilicity allows catalysts to better contact with water molecules, while its porous structure accelerates mass transfer. Furthermore, its unique three-dimensional porous framework structure gives it a large specific surface area, effectively enabling the uniform dispersion of the supported catalyst. Diatomaceous earth has been extensively studied as an excellent natural catalyst support. However, current applications based on diatomaceous earth supports often suffer from poor intrinsic conductivity and alkali resistance, hindering its large-scale application in electrocatalytic water splitting.

[0006] Therefore, it is necessary to propose new and improved technologies for the application of diatomaceous earth carriers to meet the needs of electrocatalytic water splitting applications. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the difficulties of poor conductivity and poor alkali resistance when diatomite is used as a carrier in electrocatalytic water splitting in the prior art, and to provide a method for preparing a metal-diatomite carrier for electrocatalytic water splitting.

[0008] To solve the technical problem, the solution of the present invention is:

[0009] A method for preparing a metal-diatomite support for electrocatalytic water splitting is provided, comprising the following steps:

[0010] (1) Sifting diatomaceous earth

[0011] Diatomaceous earth is placed in sufficient deionized water, heated and stirred to disperse it fully, resulting in a diatomaceous earth suspension; then it is sieved and dried to obtain diatomaceous earth.

[0012] (2) Diatomaceous earth acid leaching

[0013] The sieved diatomaceous earth is soaked in a sufficient amount of dilute acid, heated, filtered, washed, and dried to obtain acid-leached diatomaceous earth.

[0014] (3) Loading metal ions onto diatomaceous earth

[0015] Acid-leached diatomaceous earth was placed in deionized water and ultrasonically dispersed to obtain a diatomaceous earth turbid liquid. Then, a metal acetate solution was added, and the mixture was ultrasonically and stirred. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, the solid was filtered and washed to obtain metal-diatomaceous earth used as a carrier.

[0016] When calculating the amount of metal acetate added, the molecular formula of the acid-leached diatomaceous earth is regarded as SiO2, and the molar ratio of metal acetate to diatomaceous earth is 1:2.

[0017] As a preferred embodiment of the present invention, in step (1), the overall shape of the diatomite particles is similar to that of a cylindrical filter element. Its main structure is a hollow cylinder with dense holes on the side wall and blocked by adhering impurities. The sieve aperture size is 1000 to 1600 mesh, and the size range of the diatomite particles obtained after sieving is 11 to 15 μm.

[0018] As a preferred embodiment of the present invention, in step (1), the heating is carried out under a water bath at 90°C, the stirring time is 1-2 hours, and the drying temperature is 60°C.

[0019] As a preferred embodiment of the present invention, in step (2), the dilute acid is a diluted solution of hydrochloric acid, sulfuric acid or nitric acid, with a concentration of 1 to 3 mol / L.

[0020] As a preferred embodiment of the present invention, in step (2), the acid leaching is carried out under a water bath at 70-90°C for 2 hours.

[0021] As a preferred embodiment of the present invention, in step (3), the method for preparing the metal acetate solution is to add an appropriate amount of metal acetate to deionized water and sonicate until it is completely dissolved.

[0022] The metal acetate is any one of nickel acetate, cobalt acetate, zinc acetate, and copper acetate; or, it is an acetate precursor formed by mixing sodium acetate with any one of nickel sulfate tetrahydrate, nickel nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, zinc sulfate heptahydrate, and copper nitrate trihydrate.

[0023] As a preferred embodiment of the present invention, in step (3), the hydrothermal reaction is controlled at a temperature of 140-180°C and a time of 12-24 hours.

[0024] The present invention further provides an application method for the metal-diatomite support prepared by the aforementioned method, wherein the metal-diatomite support is directly used as a catalyst for electrocatalytic water splitting to produce hydrogen.

[0025] The present invention also provides another application method of the metal-diatomite support prepared by the aforementioned method, which is to use the metal-diatomite support as a carrier and then use it for electrocatalytic water splitting to produce hydrogen after further loading an electrocatalyst.

[0026] As a preferred embodiment of the present invention, the further loading of the electrocatalyst includes: adding the electrocatalyst to deionized water and ultrasonically dispersing it until completely dissolved; then transferring it to a stirred hydrothermal reactor and carrying out a hydrothermal reaction under stirring conditions; during the reaction, the stirring shaft speed is set to 700 rpm, the reaction temperature is 140-200℃, and the reaction time is 12-24 h; after the reaction is completed, the solid is filtered and washed to obtain a metal-diatomaceous earth supported catalyst for electrocatalytic water splitting to produce hydrogen; the electrocatalyst is a high-entropy material catalyst or a transition metal sulfide catalyst.

[0027] Description of the invention principle:

[0028] Diatomaceous earth's unique porous structure provides a large specific surface area, offering numerous active sites. Simultaneously, its channel structure provides rapid diffusion pathways for mass transfer. The hydrophilic silanol groups on the diatomaceous earth surface facilitate water molecule adsorption and also provide anchoring sites for the catalyst, enhancing its stability. Furthermore, various elements in diatomaceous earth, such as aluminum and iron, can enhance the catalytic activity of the catalyst through synergistic effects.

[0029] However, most existing diatomaceous earth carriers only involve acid and alkali leaching or calcination, which typically results in poor intrinsic conductivity and alkali resistance, hindering their large-scale application in electrocatalytic water splitting. Given the clogged micropores in untreated diatomaceous earth, this invention first employs acid leaching to unclog the micropores, effectively removing adhering impurities from the diatomaceous earth surface and fully revealing its porous structure. This also fully exposes the silanol groups on the diatomaceous earth surface, providing a larger specific surface area and more anchoring points for metal loading. Subsequently, metal is loaded onto the diatomaceous earth surface, which not only improves the alkali resistance of the diatomaceous earth carrier but also enhances its conductivity. The sheet-like structure formed on the diatomaceous earth surface after loading further increases its specific surface area.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. Diatomaceous earth is abundant and inexpensive, and its use as a catalyst carrier can effectively reduce production costs.

[0032] 2. After sieving, the required diatomaceous earth content in the filter cartridge form can reach more than 90%, and the acid leaching treatment can further unclog the blocked micropores of the diatomaceous earth and increase its specific surface area.

[0033] 3. The diatomaceous earth support prepared by this invention has a well-developed pore structure and a large specific surface area, which helps to uniformly disperse the catalyst, expose more active sites, and thus improve catalytic activity.

[0034] 4. The metal-diatomite support prepared by this invention can be used as part of the raw material for supported catalysts, or it can be used directly as a catalyst for electrocatalytic water splitting.

[0035] 5. Using this diatomaceous earth support to support the catalyst and applying it to HER / OER will result in lower overpotential, smaller Tafel slope, higher switching frequency and better stability. Attached Figure Description

[0036] Figure 1 The image shows the SEM morphology of the diatomaceous earth after sieving in Example 1.

[0037] Figure 2 This is a SEM image of the diatomaceous earth after acid leaching in Example 1.

[0038] Figure 3 The image shows the SEM morphology of the nickel / cobalt-diatomite in Example 1.

[0039] Figure 4 This is a SEM image of the nickel / zinc-diatomite in Example 2.

[0040] Figure 5 This is a SEM image of the nickel / copper-diatomite in Example 3.

[0041] Figure 6 This is a SEM image of the nickel-diatomite from Example 4.

[0042] Figure 7 The image shows the SEM morphology of the nickel / cobalt / copper-diatomite in Example 5.

[0043] Specific implementation details

[0044] To clarify the purpose, technical solution, and advantages of this invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0045] Part 1: Overview of the Implementation Schemes of the Invention

[0046] The method for preparing the metal-diatomite support for electrocatalytic water splitting according to the present invention includes the following steps:

[0047] (1) Sifting diatomaceous earth

[0048] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1-2 hours to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0049] The overall shape of diatomaceous earth particles is similar to that of a cylindrical filter element. Its main structure is a hollow cylinder with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of diatomaceous earth particles obtained after sieving is 11-15 μm.

[0050] (2) Diatomaceous earth acid leaching

[0051] The sieved diatomaceous earth is soaked in a sufficient amount of diluted hydrochloric acid, sulfuric acid or nitric acid solution with a concentration of 1-3 mol / L, heated in a water bath at 70-90℃ for 2 hours, filtered, washed and dried to obtain acid-impregnated diatomaceous earth.

[0052] (3) Loading metal ions onto diatomaceous earth

[0053] Add an appropriate amount of metal acetate to deionized water and sonicate until completely dissolved to obtain a metal acetate solution; the metal acetate is any one of nickel acetate, cobalt acetate, zinc acetate, and copper acetate; or, it is an acetate precursor formed by mixing sodium acetate with any one of nickel sulfate tetrahydrate, nickel nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, zinc sulfate heptahydrate, and copper nitrate trihydrate.

[0054] Acid-leached diatomaceous earth was placed in deionized water and ultrasonically dispersed to obtain a diatomaceous earth turbidity. Then, a metal acetate solution was added to the diatomaceous earth turbidity, mixed, and subjected to ultrasonication and stirring. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction, controlled at 140–180℃ for 12–24 hours. The hydrothermal reaction can be carried out without stirring, but stirring can make the reaction system more homogeneous and increase the reaction rate. After the reaction, the solid was filtered and washed to obtain the metal-diatomaceous earth used as a carrier. When calculating the amount of metal acetate added, the molecular formula of the acid-leached diatomaceous earth was considered as SiO2, and the molar ratio of metal acetate to diatomaceous earth was 1:2.

[0055] The metal-diatomite support prepared by the above process can be directly used as a catalyst for electrocatalytic water splitting to produce hydrogen.

[0056] Alternatively, the metal-diatomaceous earth support can be used as a carrier for further loading an electrocatalyst for electrocatalytic water splitting to produce hydrogen. For example, the electrocatalyst is added to deionized water and ultrasonically dispersed until completely dissolved; then transferred to a stirred hydrothermal reactor for hydrothermal reaction under stirring conditions; the stirring shaft speed is set at 700 rpm, the reaction temperature at 140–200 °C, and the reaction time at 12–24 h; after the reaction, the solid is filtered and washed to obtain a metal-diatomaceous earth supported catalyst for electrocatalytic water splitting to produce hydrogen; the electrocatalyst is a transition metal sulfide or high-entropy material catalyst, and existing publicly available technologies can be used.

[0057] Part Two: Examples of Implementation of the Invention

[0058] Example 1

[0059] This embodiment provides a nickel / cobalt-diatomite as an electrocatalyst support.

[0060] Its preparation method is as follows:

[0061] (1) Sifting diatomaceous earth

[0062] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1 hour to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0063] The diatomaceous earth particles obtained after sieving are generally in the shape of a filter element. Its main structure is a hollow column with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0064] (2) Diatomaceous earth acid leaching

[0065] The sieved diatomaceous earth was soaked in a sufficient amount of 2 mol / L sulfuric acid solution, heated in a water bath at 80°C for 2 hours, filtered, washed and dried to obtain acid-leached diatomaceous earth.

[0066] (3) Loading nickel / cobalt onto diatomaceous earth

[0067] 0.5 mmol nickel sulfate tetrahydrate, 0.5 mmol cobalt sulfate heptahydrate, and 4 mmol anhydrous sodium acetate were dissolved in 20 mL of deionized water and sonicated until completely dissolved to obtain a mixed solution of metal acetates (the total molar amount of metal acetates contained was 1 mmol); 120 mg of acid-leached diatomaceous earth (equivalent to 2 mmol) was placed in 15 mL of deionized water and sonicated to obtain a diatomaceous earth turbidity.

[0068] The diatomaceous earth turbidity was added to a metal acetate solution, mixed, and sonicated for 10 min, followed by stirring for 30 min. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction at 140℃ for 12 h. After the reaction, the solid was filtered and washed to obtain nickel / cobalt-diatomaceous earth.

[0069] Example 2

[0070] This embodiment provides a nickel / zinc-diatomite as an electrocatalyst support.

[0071] Its preparation method is as follows:

[0072] (1) Sifting diatomaceous earth

[0073] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1 hour to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0074] The diatomaceous earth particles obtained after sieving are generally in the shape of a filter element. Its main structure is a hollow column with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0075] (2) Diatomaceous earth acid leaching

[0076] The sieved diatomaceous earth was soaked in a sufficient amount of 1 mol / L nitric acid solution, heated in a water bath at 70°C for 2 hours, filtered, washed and dried to obtain acid-impregnated diatomaceous earth.

[0077] (3) Loading nickel / zinc onto diatomaceous earth

[0078] Add 0.5 mmol nickel acetate and 0.5 mmol zinc acetate to 20 mL of deionized water and sonicate until completely dissolved to obtain a mixed solution; add 120 mg acid-leached diatomaceous earth to 15 mL of deionized water and sonicate to disperse to obtain a diatomaceous earth turbid solution.

[0079] The diatomaceous earth turbidity was added to a metal acetate solution, mixed, and sonicated for 10 min, followed by stirring for 30 min. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction at 160℃ for 18 h. After the reaction, the solid was filtered and washed to obtain nickel / zinc-diatomaceous earth used as a carrier.

[0080] Example 3

[0081] This embodiment provides a nickel / copper-diatomite as an electrocatalyst support.

[0082] Its preparation method is as follows:

[0083] (1) Sifting diatomaceous earth

[0084] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1 hour to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0085] The diatomaceous earth particles obtained after sieving are generally in the shape of a filter element. Its main structure is a hollow column with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0086] (2) Diatomaceous earth acid leaching

[0087] The sieved diatomaceous earth was soaked in a sufficient amount of 2 mol / L nitric acid solution, heated in a water bath at 70°C for 2 hours, filtered, washed and dried to obtain acid-leached diatomaceous earth.

[0088] (3) Loading nickel / copper onto diatomite

[0089] Add 0.5 mmol nickel acetate and 0.5 mmol copper acetate to deionized water and sonicate until completely dissolved to obtain a mixed solution; add 120 mg acid-leached diatomaceous earth to deionized water and sonicate to disperse to obtain a diatomaceous earth turbid solution.

[0090] The diatomaceous earth turbidity was added to a metal acetate solution, mixed, and sonicated for 10 min, followed by stirring for 30 min. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction at 160℃ for 18 h. After the reaction, the solid was filtered and washed to obtain nickel / copper-diatomaceous earth used as a carrier.

[0091] Example 4

[0092] This embodiment provides a diatomaceous earth composite catalyst for alkaline OER / HER, which uses nickel-diatomaceous earth as a support to further load molybdenum disulfide, resulting in a nickel-doped molybdenum disulfide composite catalyst supported on diatomaceous earth.

[0093] Its preparation method is as follows:

[0094] (1) Sifting diatomaceous earth

[0095] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1 hour to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0096] The diatomaceous earth particles obtained after sieving are generally in the shape of a filter element. Its main structure is a hollow column with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0097] (2) Diatomaceous earth acid leaching

[0098] The sieved diatomaceous earth was soaked in a sufficient amount of 3 mol / L hydrochloric acid solution, heated in a water bath at 70°C for 2 hours, filtered, washed and dried to obtain acid-leached diatomaceous earth.

[0099] (3) Loading nickel onto diatomaceous earth

[0100] 1 mmol of nickel acetate was dissolved in 20 mL of deionized water and sonicated until completely dissolved to obtain a nickel acetate solution; 120 mg of acid-leached diatomaceous earth was placed in 15 mL of deionized water and sonicated to obtain a diatomaceous earth turbidity.

[0101] The diatomaceous earth turbidity was added to a metallic nickel solution, mixed, and sonicated for 10 minutes, followed by stirring for 30 minutes. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the solid was filtered and washed to obtain nickel-diatomaceous earth as a carrier.

[0102] (4) Molybdenum disulfide loaded on nickel-diatomite

[0103] 1 mmol of sodium molybdate dihydrate and 5 mmol of thiourea were dissolved in deionized water and sonicated until completely dissolved. 120 mg of nickel-diatomaceous earth was then added. The solution was transferred to a stirred hydrothermal reactor and hydrothermally heated at 200 °C for 20 h to obtain a nickel-doped molybdenum disulfide composite catalyst supported on diatomaceous earth.

[0104] Example 5

[0105] This embodiment provides a diatomaceous earth composite catalyst for alkaline OER / HER, which uses nickel / cobalt / copper-diatomaceous earth as a support and further loads iron and molybdenum to obtain a diatomaceous earth-supported nickel / cobalt / copper / iron / molybdenum catalyst.

[0106] Its preparation method is as follows:

[0107] (1) Sifting diatomaceous earth

[0108] Diatomaceous earth was placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1 hour to fully disperse it, thus obtaining a diatomaceous earth suspension; then it was sieved and dried in an oven at 60°C to obtain diatomaceous earth.

[0109] The diatomaceous earth particles obtained after sieving are generally in the shape of a filter element. Its main structure is a hollow column with numerous pores on the side walls that are blocked by adhering impurities. The sieve size is 1000-1600 mesh, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0110] (2) Diatomaceous earth acid leaching

[0111] The sieved diatomaceous earth was soaked in a sufficient amount of 1 mol / L hydrochloric acid solution, heated in a water bath at 90°C for 2 hours, filtered, washed and dried to obtain acid-impregnated diatomaceous earth.

[0112] (3) Loading nickel / cobalt / copper onto diatomite

[0113] 0.5 mmol nickel nitrate hexahydrate, 0.5 mmol cobalt nitrate hexahydrate, 0.5 mmol copper nitrate trihydrate, and 6 mmol anhydrous sodium acetate were dissolved in 20 mL of deionized water and sonicated until completely dissolved to obtain a mixed solution of metal acetates; 180 mg of acid-leached diatomaceous earth was placed in 15 mL of deionized water and sonicated to obtain a diatomaceous earth turbidity.

[0114] The diatomaceous earth turbidity was added to a metal acetate solution, mixed, and sonicated for 10 min, followed by stirring for 30 min. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction at 140℃ for 24 h. After the reaction, the solid was filtered and washed to obtain nickel / cobalt / copper-diatomaceous earth used as a carrier.

[0115] (4) Loading iron / molybdenum onto nickel / cobalt / copper-diatomite

[0116] 0.5 mmol sodium molybdate dihydrate and 0.5 mmol ferric chloride hexahydrate were dissolved in 35 mL of deionized water and sonicated until completely dissolved. 120 mg of nickel / cobalt / copper-diatomaceous earth was then added. The solution was transferred to a stirred hydrothermal reactor and hydrothermally heated at 140 °C for 24 h to obtain a diatomaceous earth-supported nickel / cobalt / copper / iron / molybdenum catalyst.

[0117] Part Three: Comparative Cases Different from the Invention

[0118] Comparative Example 1

[0119] We purchased commercially available diatomaceous earth from Shengzhou, Zhejiang Province, and used it as a catalyst.

[0120] Comparative Example 2

[0121] Referring to the description in patent document CN202011350694.3, a 1 mol / L sodium hydroxide solution was prepared, and 1 g of diatomaceous earth was weighed into the above alkaline solution and stirred at 25°C for 2 hours to serve as a catalyst.

[0122] Comparative Example 3

[0123] According to the patent document CN202311677978.7, 20g of industrial diatomaceous earth was placed in boiling water and stirred for 3 hours, then filtered to remove impurities such as mud and sand; the temperature was lowered to 50℃ and treated with hydrochloric acid for 6 hours; after filtration and drying, it was calcined at 500℃ in air atmosphere for 6 hours to obtain modified diatomaceous earth, which was used as a catalyst.

[0124] Comparative Example 4

[0125] Using diatomaceous earth from Comparative Example 1 as a catalyst support, and following the processing method of Example 4 of this invention, 1 mmol of nickel sulfate tetrahydrate was added to the solution, and nickel-doped molybdenum disulfide catalyst was further loaded to obtain catalyst number 4.

[0126] Comparative Example 5

[0127] Using diatomaceous earth from Comparative Example 1 as a catalyst support, and referring to the processing method of Example 5 of this invention, 0.5 mmol of nickel sulfate tetrahydrate, 0.5 mmol of cobalt nitrate hexahydrate, and 0.5 mmol of copper nitrate trihydrate were added to the solution, and a nickel / cobalt / copper / iron / molybdenum catalyst was further loaded to obtain catalyst number 5.

[0128] Part Four: Catalytic Performance Testing and Data Analysis

[0129] 1. Follow these steps to set up the test platform:

[0130] A coating solution was prepared by ultrasonically dispersing a mixture of 20 mg catalyst, 1 mL deionized water, 900 μL ethanol, and 100 μL Nafion solution (5%). The coating solution was then evenly dropped onto 0.5 cm x 0.5 cm carbon paper (25 μL on each side), resulting in a catalyst loading of approximately 1 mg / cm². 2 After drying, it is made into a working electrode.

[0131] A saturated Ag / AgCl electrode was used as the reference electrode, and a graphite rod was used as the counter electrode. The tests were conducted in a 1 mol / L KOH solution (oxygen was bubbled into the KOH solution for 30 min before the OER test, and nitrogen was bubbled into the KOH solution for 30 min before the HER test). Electrochemical performance was tested using an electrochemical workstation.

[0132] 2. Perform tests on each embodiment and comparative example according to the following procedures:

[0133] Alkaline OER test: First, cyclic voltammetry (CV) was used to scan 20 times in the range of 0-1.5V at a rate of 20mv / s to stabilize the catalytic performance of the catalyst; then, linear voltammetry (LSV) was used to test in the range of 0-1.5V at a rate of 5mv / s; finally, electrochemical impedance spectroscopy (EIS) was performed at a potential of 0.5V.

[0134] Alkaline HER test: First, perform CV cycling, scanning 20 times at a rate of 20 mv / s within the range of -1.8 to -1 V to stabilize the catalytic performance of the catalyst; then perform LSV test at a rate of 5 mv / s within the range of -1.8 to -1 V; and perform EIS test at a potential of -1.1 V.

[0135] According to the Nernst equation, the test potential is fully calibrated to a reversible hydrogen electrode: E RHE =E Ag / AgCl +0.059*pH+0.197 (for iR compensation).

[0136] 3. All embodiments and comparative examples are performed at a current density of 10 mA / cm². 2 The overpotentials at that time are shown in Table 1 below:

[0137] Table 1

[0138]

[0139] The test data from the various embodiments and comparative examples show that:

[0140] (1) When the metal-diatomite support is used alone as an alkaline OER / HER catalyst, the overpotential of Examples 1-3 of the present invention is significantly lower than that of the same use in Comparative Examples 1-3, thus proving that the catalytic performance of the catalyst of the present invention is superior to that of existing diatomite technology.

[0141] (2) When comparing catalytic performance in applications where a separate catalyst is loaded, Example 4 corresponds to the transition metal sulfide in Comparative Example 4, and Example 5 corresponds to the high-entropy material in Comparative Example 5. The overpotentials in the examples of this invention are also lower than those in the corresponding comparative examples, which proves that the catalytic performance of the catalyst described in this invention is still superior to that of existing diatomaceous earth technology.

[0142] Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a metal-diatomite support for electrocatalytic water splitting, characterized in that, Includes the following steps: (1) Sifting of diatomaceous earth Diatomaceous earth is placed in sufficient deionized water and heated and stirred in a water bath at 90°C for 1-2 hours to fully disperse it, thus obtaining a diatomaceous earth suspension. After sieving and drying, diatomaceous earth is obtained. The overall shape of the diatomaceous earth particles is cylindrical, and its main structure is a hollow cylinder with dense pores on the side walls that are blocked by adhering impurities. (2) Acid leaching of diatomaceous earth The sieved diatomaceous earth was soaked in a sufficient amount of dilute acid with a concentration of 1~3 mol / L, heated in a water bath at 70~90℃ for 2 h, filtered, washed and dried to obtain acid-impregnated diatomaceous earth. (3) Loading metal ions onto diatomaceous earth Acid-leached diatomaceous earth was placed in deionized water and ultrasonically dispersed to obtain a diatomaceous earth turbid liquid. Then, a metal acetate solution was added, and the mixture was ultrasonically and stirred. The mixture was then transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, the solid was filtered and washed to obtain metal-diatomaceous earth used as a carrier. The method for preparing the metal acetate solution is to add an appropriate amount of metal acetate to deionized water and sonicate until completely dissolved; the metal acetate is any one of nickel acetate, cobalt acetate, zinc acetate, and copper acetate; or, it is an acetate precursor formed by mixing sodium acetate with any one of nickel sulfate tetrahydrate, nickel nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, zinc sulfate heptahydrate, and copper nitrate trihydrate; When calculating the amount of metal acetate added, the molecular formula of the acid-leached diatomaceous earth is regarded as SiO2, and the molar ratio of metal acetate to diatomaceous earth is 1:

2.

2. The method according to claim 1, characterized in that, In step (1), the sieve aperture size is 1000~1600 mesh, and the size range of the diatomaceous earth particles obtained after sieving is 11~15 μm.

3. The method according to claim 1, characterized in that, In step (1), the drying temperature is 60°C.

4. The method according to claim 1, characterized in that, In step (2), the dilute acid is a diluted solution of hydrochloric acid, sulfuric acid, or nitric acid.

5. The method according to claim 1, characterized in that, In step (3), the hydrothermal reaction is carried out at a temperature of 140-180°C for 12-24 hours.

6. The application method of the metal-diatomite carrier obtained by the preparation method of claim 1, characterized in that, The metal-diatomite support is used directly as a catalyst for electrocatalytic water splitting to produce hydrogen.

7. The application method of the metal-diatomite carrier obtained by the preparation method of claim 1, characterized in that, The metal-diatomite support was used as a carrier, and after further loading an electrocatalyst, it was used for electrocatalytic water splitting to produce hydrogen.

8. The application method according to claim 7, characterized in that, The further loading of the electrocatalyst includes: adding the electrocatalyst to deionized water, ultrasonically dispersing it until completely dissolved, adding a metal-diatomaceous earth support as a carrier; then transferring it to a stirred hydrothermal reactor and carrying out a hydrothermal reaction under stirring conditions; during the reaction, the stirring shaft speed is set to 700 rpm, the reaction temperature is 140~200℃, and the reaction time is 12~24 h; after the reaction, the solid is filtered and washed to obtain a metal-diatomaceous earth supported catalyst for electrocatalytic water splitting to produce hydrogen; the electrocatalyst is a high-entropy material catalyst or a transition metal sulfide catalyst.

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