Preparation method of metal-diatomite carrier applied to electro-catalytic water decomposition

Abstract

The invention relates to a carrier technology of an inorganic catalyst, and aims to provide a preparation method of a metal-diatomite carrier applied to electro-catalytic water decomposition. The method comprises the following steps: diatomite sieving and acid leaching treatment; putting the acid-leached diatomite into deionized water, and carrying out ultrasonic dispersion treatment to obtain a diatomite turbid solution; adding a metal acetate solution, mixing, and carrying out ultrasonic and stirring treatment; and transferring the mixture into a hydrothermal kettle for hydrothermal reaction, filtering after the reaction is finished, and cleaning the solid to obtain the metal-diatomite used as the carrier. The diatomite carrier prepared by the invention has a developed pore structure and a large specific surface area, and is beneficial to uniform dispersion of a catalyst and exposure of more active sites, so that the catalytic activity is improved; the carrier can be used as a part of raw materials for loading a catalyst, or can be directly used as a catalyst to be applied to electro-catalytic water decomposition; when the material is applied to HER / OER, the overpotential is low, the Tafel slope is small, the conversion frequency is high, and the stability is good.

Description

Technical Field

[0001] The invention belongs to the carrier technology of inorganic catalysts, and in particular relates to a preparation method of a metal-diatomaceous earth carrier used for electrocatalytic water decomposition. Background Art

[0002] In order to alleviate the increasingly serious energy shortage and environmental pollution problems, it is urgent to find new energy sources to replace carbon-based energy. Hydrogen has high energy density and is environmentally friendly, and is one of the best substitutes for fossil fuels. Electrocatalytic water splitting has high conversion efficiency, hydrogen production purity and commercial value, and is currently one of the best ways to produce hydrogen. However, the decomposition of water requires a higher overpotential to overcome the slow kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes. In order to improve the performance of electrocatalytic water splitting, current research mainly focuses on the development of new catalysts, and new strategies need to be developed to further improve the catalytic performance.

[0003] Catalyst carriers usually have a large specific surface area, which can make the catalyst evenly dispersed and effectively solve the problem of catalyst agglomeration, thereby exposing more active sites and improving catalytic efficiency. Catalyst carriers can improve the utilization rate of metal atoms, reduce metal consumption, and reduce costs. In addition, the stability and catalytic activity of the catalyst can be further improved through the interaction between the carrier and the catalyst. Therefore, the use of suitable catalyst carriers to load electrocatalysts can effectively improve the performance of electrocatalytic water splitting, and researchers in the industry have proposed a variety of types of electrocatalysts.

[0004] Currently, a variety of carriers have been used to load electrocatalysts. The most common carriers are carbon carriers, such as porous nanocarbon, graphene, carbon nanotubes, etc., but in the OER process in a strongly acidic or oxidizing environment, carbon is unstable and will be oxidized or participate in the reaction. Non-carbon carriers such as metal oxides, carbides and nitrides have excellent durability and strong electronic interactions with catalysts. However, the cost of these catalyst carriers is relatively high, which limits their large-scale application. Therefore, it is necessary to develop more stable and low-cost catalyst carriers.

[0005] Diatomaceous earth is formed by the deposition of diatom remains, and its main component is amorphous silicon dioxide. As a natural mineral, it is abundant in reserves, inexpensive, and green and pollution-free. Diatomaceous earth has excellent chemical stability and thermal stability, and strong adsorption capacity. The good hydrophilicity of diatomaceous earth enables the catalyst to better contact with water molecules, and the porous channel structure can accelerate the mass transfer rate. In addition, the unique three-dimensional porous skeleton structure gives diatomaceous earth a large specific surface area, which can effectively disperse the loaded catalyst evenly. As an excellent natural catalyst carrier, diatomaceous earth has considerable research results. However, the existing applications based on diatomaceous earth carriers usually have the problems of poor intrinsic conductivity and poor alkali resistance, which makes it difficult to be widely used in electrocatalytic water decomposition.

[0006] Therefore, it is necessary to propose new improved technologies for the application of diatomaceous earth carriers to meet the needs of electrocatalytic water decomposition application scenarios. Summary of the invention

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

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

[0009] Provided is a method for preparing a metal-diatomaceous earth carrier for electrocatalytic water decomposition, comprising the following steps:

[0010] (1) Diatomaceous earth screening

[0011] The diatomaceous earth is placed in sufficient deionized water, heated and stirred to be fully dispersed to obtain a diatomaceous earth suspension; and then sieved and dried to obtain diatomaceous earth;

[0012] (2) Diatomite acid leaching

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

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

[0015] The acid-leached diatomite is placed in deionized water and subjected to ultrasonic dispersion treatment to obtain a diatomite turbid liquid; then a metal acetate solution is added, and after mixing, ultrasonic and stirring treatment is performed; the mixture is then transferred to a hydrothermal kettle for hydrothermal reaction, and after the reaction is completed, the solid is filtered and washed to obtain a metal-diatomite used as a carrier;

[0016] When calculating the amount of metal acetate to be added, the molecular formula of the diatomaceous earth after acid leaching 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 appearance of the diatomaceous earth particles is similar to a cylindrical filter element, and its main structure is a hollow cylinder, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 mesh, and the size range of the diatomaceous earth particles obtained after sieving is 11-15 μm.

[0018] As a preferred embodiment of the present invention, in the step (1), the heating is carried out in a water bath at 90°C, the stirring time is 1 to 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, and the concentration is 1 to 3 mol / L.

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

[0021] As a preferred embodiment of the present invention, in step (3), the preparation method of the metal acetate solution is to add an appropriate amount of metal acetate into deionized water and perform ultrasonic treatment 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), during the hydrothermal reaction, the temperature is controlled to be 140 to 180° C. and the time is 12 to 24 hours.

[0024] The present invention further provides an application method of the metal-diatomaceous earth carrier prepared by the above method, which is to use the metal-diatomaceous earth carrier directly as a catalyst for electrocatalytic decomposition of water to produce hydrogen.

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

[0026] As a preferred embodiment of the present invention, the operation of further loading the electrocatalyst includes: adding the electrocatalyst into deionized water, ultrasonically dispersing until completely dissolved; then transferring to a stirred hydrothermal kettle, and performing a hydrothermal reaction under stirring conditions; during the reaction, the speed of the stirring shaft is set to 700 rpm, the reaction temperature is 140-200°C, and the reaction time is 12-24 hours; after the reaction is completed, filtering and washing the solid to obtain a metal-diatomaceous earth-loaded catalyst for electrocatalytic decomposition of water to produce hydrogen; the electrocatalyst is a high entropy material catalyst or a transition metal sulfide catalyst.

[0027] Description of the invention principle:

[0028] The special porous structure of diatomite has a large specific surface area and can provide a large number of active sites. At the same time, the channel structure of diatomite provides a fast diffusion channel for mass transfer. The hydrophilicity of the silanol groups on the surface of diatomite is conducive to the adsorption of water molecules. At the same time, the silanol groups provide anchoring points for the catalyst, which improves the stability of the catalyst. In addition, various elements in diatomite, such as aluminum and iron, can improve the catalytic activity of the catalyst through synergistic effects with the catalyst.

[0029] However, most of the existing diatomite carriers are only treated by acid-base leaching or calcination of diatomite, which usually has the problems of poor intrinsic conductivity and poor alkali resistance, making it difficult to obtain large-scale application in electrocatalytic water decomposition. In view of the situation that the micropores in untreated diatomite are blocked, the present invention first uses acid leaching treatment to dredge the micropores, effectively removes the adhered impurities on the surface of diatomite, and fully displays the porous structure of diatomite, while fully exposing the silanol group on the surface of diatomite, providing a larger specific surface area and more anchoring points for the metal load. Then, metal is loaded on the surface of diatomite, which not only improves the alkali resistance of the diatomite carrier, but also enhances its electrical conductivity. The sheet structure formed on the surface of diatomite after loading can further increase its specific surface area.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

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

[0032] 2. After screening, the required filter element diatomaceous earth content can reach more than 90%, and the acid leaching treatment can further dredge the blocked micropores of the diatomaceous earth and increase the specific surface area of ​​the diatomaceous earth.

[0033] 3. The diatomaceous earth carrier prepared by the present invention has a developed pore structure and a large specific surface area, which helps to evenly disperse the catalyst and expose more active sites, thereby improving the catalytic activity.

[0034] 4. The metal-diatomaceous earth carrier prepared in the present invention can be used as part of the raw material for loading the catalyst, and can also be directly used as a catalyst for electrocatalytic water decomposition.

[0035] 5. The diatomite carrier-supported catalyst applied to HER / OER will have lower overpotential, smaller Tafel slope, higher conversion frequency and better stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the SEM morphology of the sieved diatomaceous earth in Example 1.

[0037] Figure 2 This is the SEM morphology of the diatomite after acid leaching in Example 1.

[0038] Figure 3 This is the SEM morphology of nickel / cobalt-diatomaceous earth in Example 1.

[0039] Figure 4 This is the SEM morphology of nickel / zinc-diatomaceous earth in Example 2.

[0040] Figure 5 This is the SEM morphology of nickel / copper-diatomaceous earth in Example 3.

[0041] Figure 6 This is the SEM morphology of nickel-diatomite in Example 4.

[0042] Figure 7 This is the SEM morphology of nickel / cobalt / copper-diatomaceous earth in Example 5.

[0043] Specific implementation content

[0044] In order to clarify the implementation objectives, technical solutions and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation modes.

[0045] Part I Overview of the Implementation Scheme of the Invention

[0046] The method for preparing the metal-diatomaceous earth carrier for electrocatalytic water decomposition of the present invention comprises the following steps:

[0047] (1) Diatomaceous earth screening

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

[0049] The overall appearance of diatomaceous earth particles is similar to a cylindrical filter element, and its main structure is a hollow cylinder with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 mesh, and the size range of the diatomaceous earth particles obtained after screening is 11-15μm.

[0050] (2) Diatomite acid leaching

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

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

[0053] An appropriate amount of metal acetate is added to deionized water and subjected to ultrasonic treatment until it is 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] The acid-leached diatomite is placed in deionized water and subjected to ultrasonic dispersion treatment to obtain a diatomite turbid liquid; then the metal acetate solution is added to the diatomite turbid liquid, mixed and subjected to ultrasonic and stirring treatment; the mixture is then transferred to a hydrothermal kettle for hydrothermal reaction, with the temperature controlled at 140-180°C and the time being 12-24 hours. The hydrothermal reaction can be achieved without stirring, but stirring can make the reaction system more uniform and increase the reaction rate. After the reaction is completed, the solid is filtered and washed to obtain the metal-diatomite used as a carrier. When calculating the amount of metal acetate added, the molecular formula of the acid-leached diatomite is regarded as SiO2, and the molar ratio of metal acetate to diatomite is 1:2.

[0055] The metal-diatomaceous earth carrier prepared by the above process can be directly used as a catalyst for electrocatalytic decomposition of water to produce hydrogen.

[0056] Alternatively, the metal-diatomite carrier is used as a carrier, and after further loading an electrocatalyst, it is used for electrocatalytic decomposition of water to produce hydrogen. For example, the electrocatalyst is added to deionized water, ultrasonically dispersed until completely dissolved; then transferred to a stirred hydrothermal kettle, and a hydrothermal reaction is carried out under stirring conditions; during the reaction, the speed of the stirring shaft is set to 700 rpm, the reaction temperature is 140-200°C, and the reaction time is 12-24 hours; after the reaction is completed, the solid is filtered and cleaned to obtain a metal-diatomite-loaded catalyst for electrocatalytic decomposition of water to produce hydrogen; the electrocatalyst is a transition metal sulfide or high entropy material catalyst, and existing public technology can be used.

[0057] Part II: Examples of the implementation of the present invention

[0058] Example 1

[0059] This example provides a nickel / cobalt-diatomaceous earth for use as an electrocatalyst support.

[0060] The preparation method is as follows:

[0061] (1) Diatomaceous earth screening

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

[0063] The diatomaceous earth particles obtained after sieving are in the shape of a filter element as a whole, and the main structure thereof is a hollow column, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 meshes, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0064] (2) Diatomite acid leaching

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

[0066] (3) Loading nickel / cobalt on diatomite

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

[0068] The diatomite turbid liquid was added to the metal acetate solution, mixed and ultrasonicated for 10 minutes, and then stirred for 30 minutes; the mixture was then transferred to a hydrothermal kettle for hydrothermal reaction, the temperature was controlled at 140°C, and the reaction time was 12 hours. After the reaction, the solid was filtered and washed to obtain nickel / cobalt-diatomite.

[0069] Example 2

[0070] This example provides a nickel / zinc-diatomaceous earth for use as an electrocatalyst support.

[0071] The preparation method is as follows:

[0072] (1) Diatomaceous earth screening

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

[0074] The diatomaceous earth particles obtained after sieving are in the shape of a filter element as a whole, and the main structure thereof is a hollow column, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 meshes, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0075] (2) Diatomite acid leaching

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

[0077] (3) Loading nickel / zinc on diatomite

[0078] 0.5 mmol nickel acetate and 0.5 mmol zinc acetate were added to 20 mL deionized water, and ultrasonic treatment was performed until they were completely dissolved to obtain a mixed solution; 120 mg acid-leached diatomaceous earth was placed in 15 mL deionized water, and ultrasonic dispersion treatment was performed to obtain a diatomaceous earth turbid solution;

[0079] The diatomite turbid liquid was added to the metal acetate solution, and then ultrasonicated for 10 minutes after mixing, and then stirred for 30 minutes; then the mixture was transferred to a hydrothermal kettle for hydrothermal reaction, and the temperature was controlled at 160°C for 18 hours. After the reaction, the solid was filtered and washed to obtain nickel / zinc-diatomite used as a carrier.

[0080] Example 3

[0081] This example provides a nickel / copper-diatomaceous earth used as an electrocatalyst support.

[0082] The preparation method is as follows:

[0083] (1) Diatomaceous earth screening

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

[0085] The diatomaceous earth particles obtained after sieving are in the shape of a filter element as a whole, and the main structure thereof is a hollow column, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 meshes, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0086] (2) Diatomite acid leaching

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

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

[0089] 0.5 mmol nickel acetate and 0.5 mmol copper acetate were added into deionized water and subjected to ultrasonic treatment until they were completely dissolved to obtain a mixed solution; 120 mg acid-leached diatomaceous earth was placed into deionized water and subjected to ultrasonic dispersion treatment to obtain a diatomaceous earth turbid solution;

[0090] The diatomite turbid liquid was added to the metal acetate solution, and then ultrasonicated for 10 minutes after mixing, and then stirred for 30 minutes; then the mixture was transferred to a hydrothermal kettle for hydrothermal reaction, and the temperature was controlled at 160°C for 18 hours. After the reaction, the solid was filtered and washed to obtain nickel / copper-diatomite used as a carrier.

[0091] Example 4

[0092] This embodiment provides a diatomaceous earth composite catalyst for alkaline OER / HER, using nickel-diatomaceous earth as a carrier to additionally load molybdenum disulfide to obtain a diatomaceous earth-loaded nickel-doped molybdenum disulfide composite catalyst.

[0093] The preparation method is as follows:

[0094] (1) Diatomaceous earth screening

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

[0096] The diatomaceous earth particles obtained after sieving are in the shape of a filter element as a whole, and the main structure thereof is a hollow column, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 meshes, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0097] (2) Diatomite acid leaching

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

[0099] (3) Loading Nickel on Diatomaceous Earth

[0100] 1 mmol of nickel acetate was dissolved in 20 mL of deionized water, and ultrasonicated 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 ultrasonically dispersed to obtain a diatomaceous earth turbid solution;

[0101] The diatomite turbid liquid was added to the nickel solution, and then ultrasonicated for 10 minutes after mixing, and then stirred for 30 minutes; then the mixture was transferred to a hydrothermal kettle for hydrothermal reaction, and the temperature was controlled at 180°C for 24 hours. After the reaction, the solid was filtered and washed to obtain nickel-diatomite used as a carrier.

[0102] (4) Loading MoS2 on Nickel-Kieselguhr

[0103] Dissolve 1 mmol of sodium molybdate dihydrate and 5 mmol of thiourea in deionized water, sonicate until completely dissolved, and add 120 mg of nickel-diatomite. Transfer the solution to a stirred hydrothermal reactor, set the speed to 700 rpm, and hydrothermal at 200°C for 20 hours to obtain a diatomite-supported nickel-doped molybdenum disulfide composite catalyst.

[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 carrier, and separately loads iron and molybdenum to obtain a diatomaceous earth-supported nickel / cobalt / copper / iron / molybdenum catalyst.

[0106] The preparation method is as follows:

[0107] (1) Diatomaceous earth screening

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

[0109] The diatomaceous earth particles obtained after sieving are in the shape of a filter element as a whole, and the main structure thereof is a hollow column, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 meshes, and the size range of the obtained diatomaceous earth particles is 11-15 μm.

[0110] (2) Diatomite acid leaching

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

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

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

[0114] The diatomite turbid liquid was added to the metal acetate solution, and then ultrasonicated for 10 minutes after mixing, and then stirred for 30 minutes; then the mixture was transferred to a hydrothermal kettle for hydrothermal reaction, and the temperature was controlled at 140°C for 24 hours. After the reaction, the solid was filtered and washed to obtain nickel / cobalt / copper-diatomite used as a carrier.

[0115] (4) Iron / Molybdenum Loading on Nickel / Cobalt / Copper-Diatomite

[0116] Dissolve 0.5 mmol sodium molybdate dihydrate and 0.5 mmol ferric chloride hexahydrate in 35 mL deionized water, sonicate until completely dissolved, add 120 mg nickel / cobalt / copper-diatomaceous earth. Transfer the solution to a stirred hydrothermal kettle, set the speed to 700 rpm, and hydroheat at 140°C for 24 hours to obtain a diatomaceous earth-supported nickel / cobalt / copper / iron / molybdenum catalyst.

[0117] Part III. Comparative Examples Different from the Present Invention

[0118] Comparative Example 1

[0119] The commercially available Zhejiang Shengzhou diatomaceous earth was purchased and used as a catalyst.

[0120] Comparative Example 2

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

[0122] Comparative Example 3

[0123] Referring to the records in patent document CN202311677978.7, 20g of industrial diatomaceous earth was placed in boiling water and stirred for 3 hours, and impurities such as mud and sand were filtered out; the temperature was lowered to 50°C, and the mixture was soaked in hydrochloric acid for 6 hours; after filtering and drying, the mixture was calcined at 500°C in an air atmosphere for 6 hours to obtain modified diatomaceous earth, which was used as a catalyst.

[0124] Comparative Example 4

[0125] The diatomaceous earth of comparative example 1 was used as a catalyst carrier, and the treatment method of Example 4 of the present invention was referred to. At the same time, 1 mmol of nickel sulfate tetrahydrate was added to the solution, and a nickel-doped molybdenum disulfide catalyst was further added to obtain a catalyst with serial number 4.

[0126] Comparative Example 5

[0127] The diatomaceous earth of Comparative Example 1 was used as a catalyst carrier, and the treatment method of Example 5 of the present invention was referred to. At the same time, 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 added to obtain a catalyst No. 5.

[0128] Part IV Catalytic performance testing and data analysis

[0129] 1. Follow the steps below to build a test platform:

[0130] 20 mg of catalyst, 1 mL of deionized water, 900 μL of ethanol, and 100 μL of nafion solution (5%) were mixed and ultrasonically dispersed to prepare a coating solution. The coating solution was evenly dropped on 0.5 cm*0.5 cm carbon paper (25 μL on each side). The catalyst loading was about 1 mg / cm 2 , and then dried to form 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 test was carried out in a 1 mol / L KOH solution (oxygen was passed into the KOH solution for 30 min before the OER test, and nitrogen was passed into the KOH solution for 30 min before the HER test). The electrochemical performance test was carried out using an electrochemical workstation.

[0132] 2. Carry out the tests of each embodiment and comparative example according to the following operation contents:

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

[0134] Alkaline HER test: First, CV cycle was performed, and the catalytic performance of the catalyst was stabilized at a rate of 20mv / s in the range of -1.8--1V; then LSV test was performed at a rate of 5mv / s in the range of -1.8--1V; EIS test was performed at a potential of -1.1V.

[0135] The test potentials were all calibrated to a reversible hydrogen electrode according to the Nernst equation: E RHE =E Ag / AgCl +0.059*pH+0.197 (perform iR compensation).

[0136] 3. The current density of each embodiment and comparative example is 10mA / cm 2 The overpotential at this time is shown in Table 1:

[0137] Table 1

[0138]

[0139] From the test data of each embodiment and comparative example, it can be seen that:

[0140] (1) When the metal-diatomaceous earth carrier is used alone as an alkaline OER / HER catalyst, Examples 1-3 of the present invention have lower overpotentials than those of Comparative Examples 1-3 when the metal-diatomaceous earth carrier is used alone, and the difference is obvious, thus proving that the catalytic performance of the catalyst of the present invention is superior to that of the existing diatomaceous earth technology.

[0141] (2) When comparing the catalytic performance in the use scenario of separately loaded catalysts, 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 overpotential in the examples of the present invention is also lower than that in the corresponding comparative examples, which can prove that the catalytic performance of the catalyst of the present invention is still better than the existing diatomaceous earth technology.

[0142] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing a metal-diatomaceous earth carrier for electrocatalytic water decomposition, characterized in that: The following steps are involved: (1) Diatomaceous earth screening The diatomaceous earth is placed in sufficient deionized water, heated and stirred to be fully dispersed to obtain a diatomaceous earth suspension; and then sieved and dried to obtain diatomaceous earth; (2) Diatomite acid leaching The sieved diatomaceous earth is soaked in a sufficient amount of dilute acid, and after heating, filtered, washed and dried to obtain acid-leached diatomaceous earth; (3) Loading metal ions on diatomaceous earth The acid-leached diatomite is placed in deionized water and subjected to ultrasonic dispersion treatment to obtain a diatomite turbid liquid; then a metal acetate solution is added, and after mixing, ultrasonic and stirring treatment is performed; the mixture is then transferred to a hydrothermal kettle for hydrothermal reaction, and after the reaction is completed, the solid is filtered and washed to obtain a metal-diatomite used as a carrier; When calculating the amount of metal acetate to be added, the molecular formula of the diatomaceous earth after acid leaching 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 the step (1), the overall shape of the diatomaceous earth particles is similar to a cylindrical filter element, and its main structure is a hollow cylinder, with dense holes on the side walls and blocked by adherent impurities; the sieve hole size is 1000-1600 mesh, and the size range of the diatomaceous earth particles obtained after screening is 11-15 μm.

3. The method according to claim 1, characterized in that In the step (1), the heating is carried out in a water bath at 90°C, the stirring time is 1 to 2 hours, and the drying temperature is 60°C.

4. The method according to claim 1, characterized in that: In the step (2), the dilute acid is a diluted solution of hydrochloric acid, sulfuric acid or nitric acid, and the concentration is 1 to 3 mol / L.

5. The method according to claim 1, characterized in that In the step (2), the acid leaching is carried out in a water bath at 70-90° C. for 2 hours.

6. The method according to claim 1, characterized in that In the step (3), the metal acetate solution is prepared by adding an appropriate amount of metal acetate into deionized water and ultrasonically treating the water until the water is 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.

7. The method according to claim 1, characterized in that In the step (3), during the hydrothermal reaction, the temperature is controlled to be 140 to 180° C. and the time is 12 to 24 hours.

8. The application method of the metal-diatomaceous earth carrier prepared by the method of claim 1, characterized in that: The metal-diatomaceous earth carrier is directly used as a catalyst for electrocatalytic decomposition of water to produce hydrogen.

9. The application method of the metal-diatomaceous earth carrier prepared by the method of claim 1, characterized in that: The metal-diatomaceous earth carrier is used as a carrier and is used for electrocatalytic decomposition of water to produce hydrogen after further loading an electrocatalyst.

10. The method according to claim 1, characterized in that The operation of further loading the electrocatalyst includes: adding the electrocatalyst into deionized water, and ultrasonically dispersing it until it is completely dissolved; then transferring it to a stirring hydrothermal kettle, and performing a hydrothermal reaction under stirring conditions; during the reaction, the speed of the stirring shaft is set to 700 rpm, the reaction temperature is 140-200° C., and the reaction time is 12-24 hours; after the reaction is completed, filtering and washing the solid to obtain a metal-diatomaceous earth-loaded catalyst for electrocatalytic decomposition of water to produce hydrogen; the electrocatalyst is a high entropy material catalyst or a transition metal sulfide catalyst.

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