Supported composite oxygen evolution catalyst and preparation method thereof

Abstract

The invention provides a supported composite oxygen evolution catalyst and a preparation method thereof. The supported composite oxygen evolution catalyst comprises a nitride carrier of a transition metal element and CoOx supported on the nitride carrier, x is 1-1.5, and the transition metal element is selected from any one or more of a titanium element, a niobium element and a tantalum element. According to the supported composite oxygen evolution catalyst, through the synergistic effect of the nitride carrier and CoOx, the surface property and the pore structure of the supported composite oxygen evolution catalyst are adjusted, for example, the specific surface area is increased, and the pore size distribution is optimized, so that the adsorption of reactants and the desorption of products are facilitated, the activity and the selectivity of the catalyst are improved, and the service life of the catalyst is prolonged. Therefore, the problems that the oxygen evolution catalyst is poor in catalytic activity and stability and high in cost are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oxygen evolution catalysts, in particular to a supported composite oxygen evolution catalyst and a preparation method thereof. BACKGROUND

[0002] In the face of increasing global demand for clean energy, renewable energy technologies such as solar and wind energy are developing rapidly and showing great potential. However, these energy sources have the characteristics of intermittency and instability, which seriously hinders their efficient use. In this context, water electrolysis hydrogen production technology, as an important way to realize large-scale production of hydrogen energy, has received widespread attention. Water electrolysis hydrogen production technology is considered an important part of the future energy system due to its green and sustainable characteristics. Among them, the oxygen evolution reaction (OER) process occurring at the anode plays a decisive role in the energy consumption and hydrogen production rate of the entire electrolysis process. Currently, the oxygen evolution catalysts used in commercial applications are mainly based on the precious metal iridium and its oxides. Although these catalysts have high catalytic activity, the scarcity of resources and high extraction and refining costs make the cost of water electrolysis hydrogen production high, greatly limiting the large-scale commercialization and application of the technology.

[0003] The oxygen evolution reaction (OER) is a key half-reaction in the process of water electrolysis, with slow kinetics and high overpotential, which is one of the main bottlenecks limiting the improvement of water electrolysis efficiency and the reduction of cost. Traditional noble metal catalysts have good catalytic performance, but due to their scarcity and high cost, they seriously limit large-scale practical application, prompting researchers to turn their attention to non-noble metal catalysts with abundant reserves and low cost. However, traditional non-noble metal oxygen evolution catalysts still have the following problems: First, the adsorption and activation ability of non-noble metal catalysts for reactants in the oxygen evolution reaction is poor, which leads to the need for a high overpotential, and a high overpotential means more energy consumption, a significant reduction in energy utilization efficiency, a significant increase in hydrogen production cost, and difficulty in meeting actual application requirements. Second, the substrate is poor in acid resistance, and in an acidic environment, many substrate materials are easily corroded, weakening the support of the catalyst, which not only reduces the electron transport efficiency between the catalyst and the electrode, but also further affects the catalyst activity, ultimately leading to a decrease in oxygen evolution reaction performance. Third, when building a composite catalyst system, the interface bonding force between the substrate and the catalyst plays a key role in the overall performance, and traditional catalysts have weak bonding force between the substrate and the active component, which cannot provide stable support for the catalyst. In the reaction process, insufficient interface bonding force will cause the catalyst and the substrate to separate, resulting in the loss of active components and a decrease in activity, which seriously affects the overall performance of the composite catalyst.

[0004] To promote the electrolysis of water to hydrogen technology to be practical, it is urgent to develop efficient and low-cost non-noble metal oxygen evolution catalyst. In recent years, researchers have carried out a large number of researches around non-noble metal catalysts, but the existing non-noble metal oxygen evolution catalysts still have many problems. The common cobalt-based, nickel-based and other non-noble metal catalysts are difficult to reduce the activation energy of the oxygen evolution reaction due to the limitations of electronic structure and crystal structure, and need a higher overpotential in the anode reaction of water electrolysis to hydrogen, which increases the energy consumption and leads to low energy utilization efficiency. At the same time, the number of active sites is small and the adsorption and conversion ability of the reactants is poor, so the oxygen evolution reaction rate cannot meet the demand of large-scale industrial production. Moreover, some catalysts have poor stability after long-term operation, and are prone to structural damage and loss of active sites, which cannot meet the requirements of long-term stable operation of catalysts for industrial production.

[0005] Therefore, it is very important to develop an oxygen evolution catalyst with excellent performance and low cost. SUMMARY

[0006] The main purpose of the present application is to provide a supported composite oxygen evolution catalyst and a preparation method thereof, so as to solve the problems of poor catalytic activity and stability and high cost of the existing oxygen evolution catalyst.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a supported composite oxygen evolution catalyst is provided, which comprises a nitride carrier of a transition metal element and CoO x supported on the nitride carrier, wherein x is 1-1.5, and the transition metal element is selected from any one or more of titanium element, niobium element and tantalum element.

[0008] Further, the mass ratio of the above-mentioned nitride carrier and CoO x is 0.8-1.2:1.5-3.

[0009] Further, the specific surface area of the above-mentioned supported composite oxygen evolution catalyst is 35-55m 2 / g; and / or the average particle size of the supported composite oxygen evolution catalyst is 30-300nm.

[0010] Further, in the electrolysis of water oxygen evolution reaction of a three-electrode system, the Tafel slope of the above-mentioned supported composite oxygen evolution catalyst is 53-75mV·dec -1 tested in 0.5mol / L H2SO4 solution environment; and / or the overpotential η -2 required by the supported composite oxygen evolution catalyst to reach 10mA·cm 10 current density in an acidic environment with pH=0.3 is 330-399mV.

[0011] According to another aspect of the present application, a preparation method of the supported composite oxygen evolution catalyst is provided, which comprises: step S1, sequentially performing acidification treatment, washing and centrifugation and drying on a nitride carrier of a transition metal element by using concentrated hydrochloric acid to obtain a nitride carrier; step S2, sequentially adding hexadecyl trimethyl ammonium bromide and a solvent in the nitride carrier to perform a first heating reflux reaction to obtain a first primary product; step S3, sequentially adding a cobalt source and an alkaline reagent in the first primary product to perform a second heating reflux reaction to obtain a second primary product; and step S4, sequentially performing washing, centrifugation and vacuum drying on the second primary product to obtain the supported composite oxygen evolution catalyst.

[0012] Further, in the step S1, the temperature of the acidification treatment is 40-80℃, preferably 55-75℃; and / or the time of the acidification treatment is 0.5-1h.

[0013] Further, in the step S2, the concentration of the hexadecyl trimethyl ammonium bromide is 10-20mg·mL -1 , preferably 12-15mg·mL -1 ; and / or the solvent is selected from any one or more of ethylene glycol and isopropyl alcohol.

[0014] Further, in the step S3, the cobalt source is a cobalt salt aqueous solution, and the cobalt salt aqueous solution is selected from any one or more of cobalt (II) acetylacetonate aqueous solution and cobalt nitrate aqueous solution; and / or the concentration of the cobalt salt aqueous solution is 0.005-0.1mol·L -1 , preferably 0.01-0.05mol·L -1 .

[0015] Further, in the step S3, the alkaline reagent is selected from any one or more of hexamethylenetetramine aqueous solution and triphenylamine aqueous solution; and / or the concentration of the alkaline reagent is 0.005-0.1mol·L -1 , preferably 0.01-0.05mol·L -1 .

[0016] Further, the temperature of the first heating reflux reaction and the second heating reflux reaction is independently 120-180℃, preferably 140-160℃; and / or the time of the first heating reflux reaction and the second heating reflux reaction is independently 0.5-1h.

[0017] By applying the technical solution of the present application, a supported composite oxygen evolution catalyst is provided. In terms of improving catalytic activity, by precisely controlling the composite structure of the nitride carrier and CoO x , the synergistic effect of the two is utilized to improve the catalytic activity of the nitride carrier and CoO xThe strong interaction increases the number of active sites, optimizes the electronic structure and coordination environment thereof, the supported composite oxygen evolution catalyst can promote the more efficient adsorption, activation and reaction of reactants, optimizes the adsorption-desorption capacity of the supported composite oxygen evolution catalyst to reactants and intermediate products, improves the catalytic activity of the supported composite oxygen evolution catalyst, and significantly reduces the overpotential of the oxygen evolution reaction. Specifically, on the one hand, by adjusting the value of x, i.e. the content of oxygen in CoO x , the electronic structure of the catalyst can be changed, and the catalytic activity of the catalyst for the oxygen evolution reaction can be optimized. The appropriate oxygen content can promote the flow of electrons on the surface of the catalyst, improve the adsorption capacity between the active component CoO x and the reactants, thereby reducing the activation energy of the reaction, reducing the overpotential, and improving the efficiency of the oxygen evolution reaction. On the other hand, the nitride of the transition metal element (titanium element, niobium element and tantalum element) as the carrier can not only provide corrosion resistance and stability, but also adjust the surface properties and pore structure of the supported composite oxygen evolution catalyst through the synergistic effect with CoO x , such as increasing the specific surface area and optimizing the pore size distribution, thereby facilitating the adsorption of reactants and the desorption of products, and improving the activity and selectivity of the catalyst. At the same time, in the selection of raw materials, the price of the nitride carrier and CoO x is relatively low and the source is extensive, such as titanium element, niobium element and tantalum element, which have higher abundance and lower cost than noble metals such as iridium and platinum. Selecting these elements as the carrier can significantly reduce the preparation cost of the catalyst and improve the economic efficiency and feasibility of the catalyst in the industrial scale electrolytic water hydrogen production application. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings accompanying the specification of this application serve to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 The SEM and Mapping spectrum of the supported composite oxygen evolution catalyst according to the embodiment 1 of the present application is shown;

[0020] Figure 2 The polarization curve of the supported composite oxygen evolution catalyst according to the embodiment 1 of the present application in an acidic environment is shown;

[0021] Figure 3 The overpotential graph of the supported composite oxygen evolution catalyst according to the embodiment 1 of the present application is shown;

[0022] Figure 4 The Tafel curve of the supported composite oxygen evolution catalyst according to the embodiment 1 of the present application is shown. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] As described in the background section, the prior art oxygen evolution catalyst has the problems of poor catalytic activity and stability and high cost. In order to solve the above problems, the present application provides a supported composite oxygen evolution catalyst and a preparation method thereof.

[0025] In a typical embodiment of the present application, a supported composite oxygen evolution catalyst is provided, which comprises a nitride carrier of a transition metal element and CoO x , wherein x is 1-1.5, and the transition metal element is selected from any one or more of titanium element, niobium element and tantalum element.

[0026] The present application provides a supported composite oxygen evolution catalyst. In terms of improving catalytic activity, by precisely regulating the composite structure of the nitride carrier and CoO x , the synergistic effect of the two is utilized, the strong interaction between the nitride carrier and CoO x is improved, the number of active sites is increased, and the electronic structure and coordination environment thereof are optimized. The supported composite oxygen evolution catalyst of the present application can promote more efficient adsorption, activation and reaction of the reactants, and optimize the adsorption-desorption capacity of the supported composite oxygen evolution catalyst for the reactants and intermediate products, thereby improving the catalytic activity of the supported composite oxygen evolution catalyst and significantly reducing the overpotential of the oxygen evolution reaction. Specifically, on the one hand, by adjusting the value of x, i.e. the oxygen content in CoO x , the electronic structure of the catalyst can be changed, and thus the catalytic activity of the catalyst for the oxygen evolution reaction is optimized. Appropriate oxygen content can promote the flow of electrons on the surface of the catalyst, improve the adsorption capacity between the active component CoO x and the reactants, thereby reducing the activation energy of the reaction, reducing the overpotential, and improving the efficiency of the oxygen evolution reaction. On the other hand, the nitride of the transition metal element (titanium element, niobium element and tantalum element) as the carrier not only can provide corrosion resistance and stability, but also can adjust the surface properties and pore structure of the supported composite oxygen evolution catalyst through the synergistic effect with CoO x , such as increasing the specific surface area and optimizing the pore size distribution, thereby facilitating the adsorption of the reactants and the desorption of the products, and improving the activity and selectivity of the catalyst. Meanwhile, in terms of raw material selection, the nitride carrier and CoO xThe prices of these elements are relatively low and sources are widely available, such as titanium element, niobium element and tantalum element, which have higher abundance and lower cost than noble metals such as iridium, platinum and the like. Selecting these elements as carriers can significantly reduce the preparation cost of the catalyst and improve the economic efficiency and feasibility of the catalyst in the industrial-scale electrolytic water hydrogen production application.

[0027] In addition, it is preferable that x is 1-1.3.

[0028] In an embodiment of the present application, the mass ratio of the nitride carrier and CoO x is 0.8-1.2:1.5-3.

[0029] It is preferable to control the mass ratio of the nitride carrier and CoO x within the above range. On the one hand, if the loading amount of CoO x is too low, it may not be sufficient to provide enough active sites to catalyze the oxygen evolution reaction, resulting in low catalytic efficiency. On the contrary, if the loading amount of CoO x is too high, it may cause the pore blockage of the surface of the supported composite oxygen evolution catalyst, reduce the contact between the reactants and the active sites, and at the same time increase the risk of agglomeration between the active components, thereby reducing the catalytic efficiency. Controlling the mass ratio of the above nitride carrier and CoO x can promote the uniform distribution of CoO x on the surface of the nitride carrier, form abundant active sites, and maintain a good electron transport path, thereby optimizing the catalytic activity and stability of the supported composite oxygen evolution catalyst. On the other hand, the mass ratio of the nitride carrier and CoO x directly affects the interfacial bonding force between them, and too high or too low loading amount of CoO x may cause the interfacial bonding force to decrease, and fine control of this mass ratio can help to enhance the interaction of the interface, thereby improving the overall stability of the catalyst.

[0030] In an embodiment of the present application, the specific surface area of the above supported composite oxygen evolution catalyst is 35-55 m 2 / g; and / or the average particle size of the supported composite oxygen evolution catalyst is 30-300 nm, preferably 80-152 nm.

[0031] On the one hand, the increase in specific surface area means an increase in the number of active sites. In catalytic reactions, active sites are the places where reactants are adsorbed and converted. Therefore, a larger specific surface area can provide more active sites, thereby significantly improving the catalytic activity of the catalyst. For the oxygen evolution reaction (OER), more active sites contribute to the adsorption of reactants and the conversion of intermediates, reduce overpotential, and improve catalytic efficiency. On the other hand, the average particle size of the catalyst directly affects its pore structure and the diffusion path of reactants. A smaller average particle size can not only increase the specific surface area, but also form finer pores, optimize the diffusion efficiency of reactants and products, promote the reactants to quickly reach the active sites and remove the products in time, and reduce the risk of products inhibiting active sites. Therefore, it is preferred to control the specific surface area and average particle size of the supported composite oxygen evolution catalyst within the above range, thereby helping to improve the reaction rate and selectivity of the catalyst.

[0032] In one embodiment of the present application, in the electrolysis of water in a three-electrode system, the Tafel slope of the supported composite oxygen evolution catalyst was 53-75 mV·dec under a 0.5 mol / L H2SO4 solution environment. -1 ; and / or the supported composite oxygen evolution catalyst reaches 10 mA cm in an acidic environment of pH = 0.3 -2 The overpotential η required for current density 10 It is 330~399mV.

[0033] The Tafel slope is an important indicator for measuring the electrochemical reaction rate of a catalyst. A lower Tafel slope indicates that the catalyst has higher catalytic activity and can drive the same reaction rate at a lower voltage, thereby reducing energy consumption and improving the energy conversion efficiency of water electrolysis to produce hydrogen. Therefore, in this application, controlling the Tafel slope within the above range helps the catalyst exhibit faster reaction kinetics in the oxygen evolution reaction, thereby helping to improve the hydrogen generation rate and the energy efficiency of the entire system. The overpotential is the additional voltage required to reach a specific current density during the water electrolysis process to produce hydrogen, reflecting the catalyst's ability to lower the reaction energy barrier. A lower overpotential means that a lower voltage is required to achieve the same current density, thereby reducing energy consumption and cost during the electrolysis process. In this application, controlling the overpotential within the above range indicates that the catalyst exhibits good corrosion resistance and catalytic performance under acidic conditions, which helps to achieve an efficient oxygen evolution reaction at a lower voltage and helps to reduce the cost of hydrogen production. The overpotential decay rate is an indicator that measures the rate of performance degradation of a catalyst during long-term operation. The lower the decay rate, the better the stability of the catalyst, which helps to maintain its catalytic activity over a long period of time. The present application controls the overpotential decay rate within the above range, so that the degradation of catalyst performance is very slow, which helps to maintain the long life and reliability of the catalyst in industrial applications, reduce the frequency of catalyst replacement, and reduce operating costs.

[0034] In another typical embodiment of the present application, a preparation method of the above supported composite oxygen evolution catalyst is provided, which comprises: step S1, sequentially performing acidification treatment, washing and centrifugation and drying on a nitride carrier of a transition metal element by using concentrated hydrochloric acid to obtain a nitride carrier; step S2, sequentially adding hexadecyl trimethyl ammonium bromide and a solvent in the nitride carrier to perform a first heating reflux reaction to obtain a first primary product; step S3, sequentially adding a cobalt source and an alkaline reagent in the first primary product to perform a second heating reflux reaction to obtain a second primary product; and step S4, sequentially performing washing, centrifugation and vacuum drying on the second primary product to obtain the supported composite oxygen evolution catalyst.

[0035] In step S1 of the present application, the nitride carrier of the transition metal element is subjected to acidification treatment by using concentrated hydrochloric acid, which can remove surface impurities and expose more active sites, and at the same time, improve the hydrophilicity or hydrophobicity of the surface of the carrier by chemical modification, so as to provide a more active and suitable interface for the subsequent loading of CoO x . The washing and centrifugation and drying steps ensure the purity of the nitride carrier and avoid the adverse effects of impurities on the catalytic performance. In step S2, hexadecyl trimethyl ammonium bromide acts as a structure directing agent in the first heating reflux reaction, which helps to form a composite structure with a specific morphology, thereby facilitating the improvement of the specific surface area and porosity of the catalyst. At the same time, the presence of hexadecyl trimethyl ammonium bromide also helps to enhance the interfacial bonding force between the nitride carrier and the active ingredient, and improve the stability and service life of the catalyst. In the second heating reflux reaction of step S3, the cobalt source is converted into CoO x active component and is uniformly supported on the nitride carrier. The alkaline reagent participates in the regulation of the oxidation state and electronic structure of CoO x , and optimizes its catalytic performance. In step S4, the second primary product is subjected to washing, centrifugation and vacuum drying, which can remove the by-products and unreacted raw materials generated in the reaction process, and ensure the high purity of the supported composite oxygen evolution catalyst. In summary, by accurately controlling the conditions of each step in the preparation method, the catalytic activity, stability, purity and corrosion resistance of the supported composite oxygen evolution catalyst can be effectively improved, which ensures its efficient, stable and low-cost operation in the water electrolysis oxygen evolution reaction, and solves the problems of poor catalytic activity and stability and high cost of the oxygen evolution catalyst. In addition, the preparation method of the present application is simple and efficient at room temperature, which reduces the dependence on expensive equipment and creates favorable conditions for large-scale industrial production.

[0036] In an embodiment of the present application, in step S1, the acidification treatment temperature is 40-80°C, preferably 55-75°C; and / or the acidification treatment time is 0.5-1h.

[0037] A lower acidizing treatment temperature can not be able to remove impurities or modify the surface sufficiently, while a too high acidizing treatment temperature can cause the structure of the nitride support to be damaged. Preferably, the temperature of the above acidizing treatment facilitates the reaction of concentrated hydrochloric acid with the nitride support to be more sufficient, thereby effectively modifying the surface of the nitride support, increasing the active sites, and providing a more porous and high-activity nitride support for the subsequent loading of CoO x . Therefore, it is preferred to control the temperature of the acidizing treatment within the above range, which promotes surface modification and reduces the damage to the structure of the nitride support. A suitable acidizing treatment time can ensure sufficient exposure of the surface active sites and removal of impurities, while reducing the risk of excessive corrosion of the material due to too long treatment time, maintaining the structural integrity and stability of the nitride support.

[0038] In an embodiment of the present application, in the above step S2, the concentration of cetyltrimethylammonium bromide is 10-20 mg·mL -1 , preferably 12-15 mg·mL -1 ; and / or the solvent is selected from any one or more of ethylene glycol, isopropyl alcohol.

[0039] Controlling the concentration of cetyltrimethylammonium bromide within the above range, on the one hand, helps to effectively guide the morphology and distribution of CoO x nanoparticles on the nitride support, forming a composite catalyst with high specific surface area and rich pore structure, thereby improving the catalytic efficiency and stability. On the other hand, it also helps to enhance the interfacial bonding force between CoO x and the nitride support, reducing the risk of active components falling off during the catalytic process, and improving the durability of the supported composite oxygen evolution catalyst. Selecting a suitable solvent helps to promote the effective dissolution and mixing of all reaction raw materials, forming a uniform reaction system. Solvents such as ethylene glycol can promote the smooth progress of the reaction due to their good solubility and stability, reducing the risk of local overheating or precipitation of raw materials, thereby improving the uniformity and overall performance of the supported composite oxygen evolution catalyst.

[0040] In an embodiment of the present application, in the above step S3, the cobalt source is a cobalt salt aqueous solution, and the cobalt salt aqueous solution is selected from any one or more of cobalt (II) acetylacetonate aqueous solution, cobalt nitrate aqueous solution; and / or the concentration of the cobalt salt aqueous solution is 0.005-0.1 mol·L -1 , preferably 0.01-0.05 mol·L -1 .

[0041] Preferably, the type of cobalt source is controlled to be within the above range, which is conducive to promoting the better dissolution of cobalt ions in the solvent, so as to be uniformly dispersed on the surface of the nitride carrier in the heating reflux reaction, reducing the risk of local aggregation of the active component, and improving the activity and stability of the supported composite oxygen evolution catalyst. At the same time, the concentration of the aqueous cobalt salt solution is controlled to be within the above range, which is conducive to the uniform loading of cobalt ions in the aqueous cobalt salt solution on the nitride carrier, reducing the risk of insufficient loading due to too low concentration or agglomeration caused by too high concentration, and improving the excellent active site distribution of the supported composite oxygen evolution catalyst. In addition, the appropriate concentration of the aqueous cobalt salt solution also helps to form a CoO x phase with high catalytic activity and excellent stability, which is particularly crucial for the water electrolysis oxygen evolution reaction.

[0042] In an embodiment of the present application, in the step S3, the alkaline reagent is selected from any one or more of an aqueous solution of hexamethylenetetramine and an aqueous solution of triphenylamine; and / or the concentration of the alkaline reagent is 0.005-0.1 mol·L -1 , preferably 0.01-0.05 mol·L -1 .

[0043] The selection of the alkaline reagent will affect the oxidation state and electronic structure of CoO x on the nitride carrier, thereby directly affecting the catalytic activity of the supported composite oxygen evolution catalyst; on the other hand, it will also affect the nucleation and growth process of CoO x , thereby regulating the morphology and size of the particles and further affecting the catalytic performance; and the alkaline reagent can also provide a stable reaction medium for the synthesis of CoO x , promoting the reaction to proceed under mild conditions and reducing the damage to the active component or the structural changes of the carrier. Preferably, the concentration of the alkaline reagent is controlled to be within the above range, which promotes the uniform dispersion and loading of CoO x active component on the nitride carrier, reduces the risk of agglomeration caused by too high local concentration, and affects the activity and stability of the supported composite oxygen evolution catalyst. In addition, the preferred concentration range of the above alkaline reagent helps to minimize side reactions and improve the high efficiency and long life of the supported composite oxygen evolution catalyst.

[0044] In an embodiment of the present application, the temperature of the first heating reflux reaction and the second heating reflux reaction is independently 120-180°C, preferably 140-160°C; and / or the time of the first heating reflux reaction and the second heating reflux reaction is independently 0.5-1 h.

[0045] Preferably, the temperature of the first heating reflux reaction and the second heating reflux reaction is independently controlled to be within the above range, which on the one hand is conducive to the improvement of the chemical reaction rate between the reactants, and accelerates the synthesis of CoO xThe deposition and nucleation process on the nitride carrier improves the preparation efficiency; on the other hand, controlling the above temperature range helps to control the morphology and structure of CoO x and the binding state between the nitride carrier and CoO x , promoting the formation of a composite structure with high catalytic activity and stability. At the same time, controlling the above temperature range also helps to reduce the risk of carrier structure damage and active component excessive oxidation caused by excessively high temperature, promoting the stability and durability of the catalyst in subsequent use. Preferably, the time of the first heating reflux reaction and the second heating reflux reaction is independently controlled within the above range, on the one hand, it helps the chemical reaction between the reactants to proceed fully, so that CoO x active component is uniformly deposited on the surface of the nitride carrier, reducing the risk of local active site loss. On the other hand, by controlling the time of the first and second heating reflux reactions, the relationship between catalyst performance and preparation efficiency can be balanced, avoiding the risk of increased energy consumption and cost caused by excessive time, while improving the activity and stability of the supported composite oxygen evolution catalyst.

[0046] The application will be further described in detail below in conjunction with specific examples, which cannot be understood as limiting the scope of the application claimed.

[0047] Example 1

[0048] (1) Take 1g of titanium nitride (TiN) in a beaker, then add 50mL of concentrated hydrochloric acid, heat to 65℃ for acidification treatment, after 1h of reaction, then use deionized water to wash, centrifuge, vacuum dry in turn, to obtain TiN after hydrochloric acid treatment;

[0049] (2) Take 1g of TiN treated with hydrochloric acid obtained in step (1), then add 8.532g of cetyltrimethylammonium bromide, and then add 1000mL of ethylene glycol as a solvent, heat to 150℃ for the first heating reflux reaction for 1h, to obtain the first primary product;

[0050] (3) Add 10mL of 0.1M cobalt (II) acetylacetone aqueous solution and 10mL of 0.1M hexamethylenetetramine aqueous solution to the first primary product in turn, and heat to 150℃ for the second heating reflux reaction for 3h, after the reaction, cool to room temperature, to obtain the second primary product;

[0051] (4) Wash, centrifuge, and vacuum dry the second primary product obtained in step (3) using water and ethanol in turn, finally to obtain the supported composite oxygen evolution catalyst, the SEM and Mapping spectrum of which are shown in Figure 1 .

[0052] Example 2

[0053] (1) 1 g of titanium nitride (TiN) was weighed into a beaker, 50 mL of concentrated hydrochloric acid was then added, and acidification treatment was performed at 65°C, after 1 h of reaction, followed by washing, centrifugation, and vacuum drying using deionized water in sequence, to obtain TiN after hydrochloric acid treatment;

[0054] (2) 1 g of TiN after hydrochloric acid treatment obtained in step (1) was taken, 8.532 g of cetyltrimethylammonium bromide was then added, 1000 mL of ethylene glycol was used as a solvent, and first heating reflux reaction was performed at 150°C for 1 h, to obtain a first primary product;

[0055] (3) 20 mL of cobalt (II) acetylacetonate aqueous solution with a concentration of 0.05 M and 20 mL of hexamethylenetetramine aqueous solution with a concentration of 0.05 M were sequentially added to the first primary product, and second heating reflux reaction was performed at 150°C for 3 h, after the reaction, the temperature was cooled to room temperature, to obtain a second primary product;

[0056] (4) The second primary product obtained in step (3) was sequentially washed, centrifuged, and vacuum dried using water and ethanol, and finally a supported composite oxygen evolution catalyst was obtained.

[0057] Example 3

[0058] (1) 1 g of titanium nitride (TiN) was weighed into a beaker, 50 mL of concentrated hydrochloric acid was then added, and acidification treatment was performed at 65°C, after 1 h of reaction, followed by washing, centrifugation, and vacuum drying using deionized water in sequence, to obtain TiN after hydrochloric acid treatment;

[0059] (2) 1 g of TiN after hydrochloric acid treatment obtained in step (1) was taken, 8.532 g of cetyltrimethylammonium bromide was then added, 1000 mL of ethylene glycol was used as a solvent, and first heating reflux reaction was performed at 150°C for 1 h, to obtain a first primary product;

[0060] (3) 25 mL of cobalt (II) acetylacetonate aqueous solution with a concentration of 0.04 M and 25 mL of hexamethylenetetramine aqueous solution with a concentration of 0.04 M were sequentially added to the first primary product, and second heating reflux reaction was performed at 150°C for 3 h, after the reaction, the temperature was cooled to room temperature, to obtain a second primary product;

[0061] (4) The second primary product obtained in step (3) was sequentially washed, centrifuged, and vacuum dried using water and ethanol, and finally a supported composite oxygen evolution catalyst was obtained.

[0062] Example 4

[0063] (1) 1 g of titanium nitride (TiN) was weighed into a beaker, 50 mL of concentrated hydrochloric acid was then added, and acidification treatment was performed at 65°C, after 1 h of reaction, followed by washing, centrifugation, and vacuum drying using deionized water in sequence, to obtain TiN after hydrochloric acid treatment;

[0064] (2) 1 g of TiN after hydrochloric acid treatment obtained in step (1) was taken, 8.532 g of cetyltrimethylammonium bromide was then added, 1000 mL of ethylene glycol was used as a solvent, and first heating reflux reaction was performed at 150°C for 1 h, to obtain a first primary product;

[0065] (3) 50 mL of cobalt (II) acetylacetonate aqueous solution with a concentration of 0.02 M and 50 mL of hexamethylenetetramine aqueous solution with a concentration of 0.02 M were sequentially added to the first primary product, second heating reflux reaction was performed at 150°C for 3 h, after the reaction, the temperature was cooled to room temperature, to obtain a second primary product;

[0066] (4) The second primary product obtained in step (3) was sequentially washed, centrifuged, and vacuum dried using water and ethanol, to finally obtain a supported composite oxygen evolution catalyst.

[0067] Example 5

[0068] (1) 1 g of titanium nitride (TiN) was weighed into a beaker, 50 mL of concentrated hydrochloric acid was then added, and acidification treatment was performed at 65°C, after 1 h of reaction, followed by washing, centrifugation, and vacuum drying using deionized water in sequence, to obtain TiN after hydrochloric acid treatment;

[0069] (2) 1 g of TiN after hydrochloric acid treatment obtained in step (1) was taken, 8.532 g of cetyltrimethylammonium bromide was then added, 1000 mL of ethylene glycol was used as a solvent, and first heating reflux reaction was performed at 150°C for 1 h, to obtain a first primary product;

[0070] (3) 100 mL of cobalt (II) acetylacetonate aqueous solution with a concentration of 0.01 M and 100 mL of hexamethylenetetramine aqueous solution with a concentration of 0.01 M were sequentially added to the first primary product, second heating reflux reaction was performed at 150°C for 3 h, after the reaction, the temperature was cooled to room temperature, to obtain a second primary product;

[0071] (4) The second primary product obtained in step (3) was sequentially washed, centrifuged, and vacuum dried using water and ethanol, to finally obtain a supported composite oxygen evolution catalyst.

[0072] Example 6

[0073] The difference from Example 1 is that the temperature of acidification treatment is 55°C, and a supported composite oxygen evolution catalyst is finally obtained.

[0074] Example 7

[0075] The difference from Example 1 is that the temperature of acidizing treatment is 75℃, and finally a supported composite oxygen evolution catalyst is obtained.

[0076] Example 8

[0077] The difference from Example 1 is that the temperature of acidizing treatment is 80℃, and finally a supported composite oxygen evolution catalyst is obtained.

[0078] Example 9

[0079] The difference from Example 1 is that the temperature of the first heating reflux reaction is 160℃, the time of the first heating reflux reaction is 1h, and finally a supported composite oxygen evolution catalyst is obtained.

[0080] Example 10

[0081] The difference from Example 1 is that the temperature of the first heating reflux reaction is 180℃, the time of the first heating reflux reaction is 1h, and finally an oxygen evolution catalyst product CoO x / TiN is obtained.

[0082] Example 11

[0083] The difference from Example 1 is that the temperature of the second heating reflux reaction is 160℃, the time of the first heating reflux reaction is 1h, and finally a supported composite oxygen evolution catalyst is obtained.

[0084] Example 12

[0085] The difference from Example 1 is that the temperature of the second heating reflux reaction is 180℃, the time of the second heating reflux reaction is 1h, and finally a supported composite oxygen evolution catalyst is obtained.

[0086] Example 13

[0087] The difference from Example 1 is that the concentration of cobalt(II) acetylacetonate aqueous solution is 0.01 mol·L -1 , and finally a supported composite oxygen evolution catalyst is obtained.

[0088] Example 14

[0089] The difference from Example 1 is that the concentration of cobalt(II) acetylacetonate aqueous solution is 0.05 mol·L -1 , and finally a supported composite oxygen evolution catalyst is obtained.

[0090] Example 15

[0091] The difference from Example 1 is that the concentration of hexamethylenetetramine aqueous solution is 0.01 mol·L -1 , and finally a supported composite oxygen evolution catalyst is obtained.

[0092] Example 16

[0093] The difference from Example 1 is that the concentration of the hexamethylenetetramine aqueous solution is 0.05 mol·L -1 , and finally a supported composite oxygen evolution catalyst was obtained.

[0094] Comparative Example 1

[0095] The difference from Example 1 is that no acidification treatment is performed, and finally a supported composite oxygen evolution catalyst is obtained.

[0096] Comparative Example 2

[0097] The difference from Example 1 is that a nitride carrier is added to hexadecyltrimethylammonium bromide and ethylene glycol to obtain a supported composite oxygen evolution catalyst.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that the first primary product is added to the aqueous solution of cobalt (II) acetylacetonate and the aqueous solution of hexamethylenetetramine to finally obtain a supported composite oxygen evolution catalyst.

[0100] Performance testing:

[0101] Nitride support and CoO in supported composite oxygen evolution catalyst x Mass ratio: Weigh 0.1-0.5g of catalyst sample into a polytetrafluoroethylene (PTFE) digestion tube, add 10mL of aqua regia, and digest in a graphite digester at a programmed temperature of 160°C. Prepare a standard solution of the sample and calibrate the calibration curve of the inductively coupled plasma-mass spectrometer (ICP-MS) using the standard addition method. Finally, analyze the metal element content of the sample by ICP-MS. Repeat the measurement three times for each sample, and take the average value.

[0102] Specific surface area of ​​supported composite oxygen evolution catalysts: Take 100-200 mg of catalyst sample (adjust according to the specific surface area to ensure the adsorption amount is ≥0.1 mL / g) and place it in a sample tube. Record the sample mass m (accurate to 0.1 mg). Connect the sample tube to the surface area analyzer degassing station for heating and degassing. Use high-purity nitrogen as the adsorbate and helium as the carrier gas to calibrate the surface area analyzer. Then measure the adsorption-desorption curve of the catalyst sample. Finally, calculate the specific surface area of ​​the catalyst sample based on the adsorption-desorption curve and the BJH model. This method also complies with the international standard ISO9277:2010 and is suitable for quantitative characterization of catalyst specific surface area. The reliability of the results can be ensured by repeated testing (parallel samples ≤ 3 times, relative deviation ≤ 5%).

[0103] Average particle size of the supported composite oxygen evolution catalyst: 5-10 mg of catalyst powder (concentration 0.1-1.0 mg / mL) was taken in a 50 mL centrifuge tube. Then 20 mL of ethanol was added as a dispersion medium, and the sample was ultrasonically dispersed at room temperature for more than 60 min. Finally, the particle size distribution of the catalyst sample was tested by a laser particle size analyzer.

[0104] The mass ratio of nitride support and CoO x , the specific surface area and average particle size of the supported composite oxygen evolution catalyst of the above examples and comparative examples were tested, and the test data are shown in Table 1.

[0105] Table 1

[0106]

[0107] The supported composite oxygen evolution catalysts obtained in the above examples and comparative examples were prepared into catalyst ink, and the Tafel slope of the supported composite oxygen evolution catalyst was tested in the electrolytic water oxygen evolution reaction of a three-electrode system in a 0.5 mol / L H2SO4 solution environment; the overpotential η required for the supported composite oxygen evolution catalyst to reach a current density of 10 mA·cm-2 in an acidic environment with pH = 0.3; the decay rate of the overpotential η when the supported composite oxygen evolution catalyst was stably operated at a current density of 1 A·cm-2 for 350 h, and the test results are shown in Table 2. -2 10 -2 10

[0108] Table 2

[0109]

[0110] From the above description, it can be seen that the above examples of the present application achieve the following technical effects:

[0111] The present application provides a supported composite oxygen evolution catalyst. In order to improve the catalytic activity, the composite structure of the nitride support and CoO x is precisely controlled, the strong interaction between the nitride support and CoO x is improved by using the synergistic effect of the two, the number of active sites is increased, and the electronic structure and coordination environment thereof are optimized. The supported composite oxygen evolution catalyst of the present application can promote the more efficient adsorption, activation and reaction of the reactants, and optimize the adsorption-desorption capacity of the supported composite oxygen evolution catalyst for the reactants and intermediate products, thereby improving the catalytic activity of the supported composite oxygen evolution catalyst and significantly reducing the overpotential of the oxygen evolution reaction. Specifically, on the one hand, the value of x, i.e. the CoO x ​​​​The content of oxygen can change the electronic structure of the catalyst, and then optimize its catalytic activity for the oxygen evolution reaction. The appropriate oxygen content can promote the flow of electrons on the surface of the catalyst, improve the activity of the active component CoO x The adsorption capacity between the reactants, thereby reducing the activation energy of the reaction, reducing the overpotential, and improving the efficiency of the oxygen evolution reaction. On the other hand, the nitrides of transition metal elements (titanium elements, niobium elements and tantalum elements) as carriers not only can provide corrosion resistance and stability, but also can adjust the surface properties and pore structure of the supported composite oxygen evolution catalyst through the synergistic effect with CoO x , such as increasing the specific surface area, optimizing the pore size distribution, thereby facilitating the adsorption of reactants and the desorption of products, and improving the activity and selectivity of the catalyst. At the same time, in the selection of raw materials, the price of the nitride carrier and CoO x is relatively low and the source is extensive, such as titanium elements, niobium elements and tantalum elements have higher abundance and lower cost than noble metals such as iridium, platinum and the like, and selecting these elements as carriers can significantly reduce the preparation cost of the catalyst and improve its economic efficiency and feasibility in the industrial scale water electrolysis hydrogen production application.

[0112] The above is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A supported composite oxygen evolution catalyst, characterized in that: The supported composite oxygen evolution catalyst comprises a nitride support of a transition metal element and CoO supported on the nitride support. x , wherein x is 1 to 1.5, and the transition metal element is selected from any one or more of titanium, niobium and tantalum.

2. The supported composite oxygen evolution catalyst according to claim 1, characterized in that The nitride support and the CoO x The mass ratio is 0.8~1.2:1.5~3.

3. The supported composite oxygen evolution catalyst according to claim 1, characterized in that The specific surface area of ​​the supported composite oxygen evolution catalyst is 35 to 55 m 2 / g; and / or the average particle size of the supported composite oxygen evolution catalyst is 30 to 300 nm.

4. The supported composite oxygen evolution catalyst according to claim 1, characterized in that In the oxygen evolution reaction of water electrolysis in a three-electrode system, the Tafel slope of the supported composite oxygen evolution catalyst was 53-75 mV·dec in a 0.5 mol / L H2SO4 solution environment. -1 and / or the supported composite oxygen evolution catalyst reaches 10 mA·cm in an acidic environment of pH = 0.3 -2 The overpotential η required for current density 10 330~399mV.

5. A method for preparing the supported composite oxygen evolution catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Step S1, acidifying the transition metal element nitride carrier with concentrated hydrochloric acid, washing, centrifuging, and drying in sequence to obtain the nitride carrier; Step S2, adding cetyltrimethylammonium bromide and a solvent in sequence to the nitride carrier to perform a first heating reflux reaction to obtain a first initial product; Step S3, sequentially adding a cobalt source and an alkaline reagent to the first primary product to perform a second heating reflux reaction to obtain a second primary product; Step S4, washing, centrifuging, and vacuum drying the second primary product in sequence to obtain the supported composite oxygen evolution catalyst.

6. The method for preparing a supported composite oxygen evolution catalyst according to claim 5, wherein: In the step S1, the temperature of the acidification treatment is 40 to 80° C., preferably 55 to 75° C.; and / or the time of the acidification treatment is 0.5 to 1 hour.

7. The method for preparing the supported composite oxygen evolution catalyst according to claim 5 or 6, characterized in that: In step S2, the concentration of cetyltrimethylammonium bromide is 10-20 mg·mL -1 , preferably 12 to 15 mg·mL -1 and / or The solvent is selected from any one or more of ethylene glycol and isopropyl alcohol.

8. The method for preparing the supported composite oxygen evolution catalyst according to any one of claims 5 to 7, characterized in that: In step S3, the cobalt source is a cobalt salt aqueous solution, and the cobalt salt aqueous solution is selected from any one or more of an acetylacetonate cobalt (II) aqueous solution and a cobalt nitrate aqueous solution; and / or the concentration of the cobalt salt aqueous solution is 0.005 to 0.1 mol·L -1 , preferably 0.01 to 0.05 mol·L -1 .

9. The method for preparing the supported composite oxygen evolution catalyst according to any one of claims 5 to 8, characterized in that: In step S3, the alkaline reagent is selected from any one or more of a hexamethylenetetramine aqueous solution and a triphenylamine aqueous solution; and / or the concentration of the alkaline reagent is 0.005 to 0.1 mol·L -1 , preferably 0.01 to 0.05 mol·L -1 .

10. The method for preparing the supported composite oxygen evolution catalyst according to any one of claims 5 to 9, characterized in that: The temperature of the first heating reflux reaction and the second heating reflux reaction are each independently 120 to 180° C., preferably 140 to 160° C.; and / or the time of the first heating reflux reaction and the second heating reflux reaction are each independently 0.5 to 1 h.

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