An iridium cobalt oxide electrocatalyst, its preparation method, and its application.

Abstract

This invention provides an iridium cobalt oxide electrocatalyst, its preparation method, and its application. First, metallic Co is electrodeposited onto a Ti fiber mat, and then it is placed in an Ir... 3+ In solution, an electrochemical displacement reaction driven by the potential difference between two metals successfully deposited the noble metal Ir onto the surface of metallic Co. Finally, calcination in air yielded an iridium-cobalt oxide electrocatalyst. This invention utilizes an electrochemical displacement reaction to synthesize an iridium-cobalt oxide electrocatalyst simply and conveniently, by altering the noble metal Ir. 3+ By controlling the coordination environment of noble metal active sites through concentration and reaction time, a highly efficient and stable iridium-cobalt oxide was successfully constructed on the surface as an oxygen-generating active center. This solves the problems of high noble metal loading, low activity, and low stability in existing acidic oxygen-generating electrocatalysts, providing a simple, rapid, low-cost, and efficient solution for industrial-scale production.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, and specifically relates to an iridium cobalt oxide electrocatalyst, its preparation method, and its application. Background Technology

[0002] Developing clean and renewable hydrogen energy is one of the important ways to achieve energy decarbonization. Considering both hydrogen sources and costs, water electrolysis technology driven by renewable energy is considered the main route for hydrogen production. Currently, mainstream water electrolysis hydrogen production technologies can be divided into alkaline water electrolyzers and proton exchange membrane (PEM) water electrolyzers. Compared to alkaline water electrolyzers, PEM water electrolyzers have advantages such as higher hydrogen purity, higher current density, and better energy utilization efficiency, and therefore have attracted widespread attention. However, the highly acidic working environment in PEM water electrolyzers limits the development of this technology. The electrocatalysts used at both the hydrogen and oxygen production ends often contain large amounts of precious metals such as Pt and Ir (non-precious metals have low stability and low activity under strong acid conditions). Furthermore, the oxygen production end involves a four-electron transfer electrochemical process, which has a higher kinetic barrier than the two-electron transfer hydrogen production end, requiring the application of high overpotentials to obtain high current densities. This is one of the important problems that water electrolysis hydrogen production needs to address. In summary, there is an urgent need to develop acidic oxygen-generating electrocatalysts with low noble metal loading and high efficiency and stability.

[0003] To date, RuO2 and IrO2 are the most studied acidic oxygen-generating electrocatalysts. RuO2 typically exhibits high activity, but it quickly dissolves and deactivates during operation. While IrO2 has slightly lower activity, its stability is far superior to RuO2, making it the most widely used commercially available acidic oxygen-generating electrocatalyst. The dissolution and deactivation of IrO2 (or RuO2) catalysts under operating voltage is fundamentally due to the excessively high adsorption energy between the oxygen-generating sites of noble metals and oxygen-containing intermediates. By controlling the coordination environment (bond length, charge distribution, etc.) around the noble metal, the adsorption process of the oxygen-generating sites and intermediates can be affected, providing a pathway to improve catalyst activity and stability. Besides activity and stability, another pressing issue in the synthesis of acidic oxygen-generating electrocatalysts using noble metals is how to reduce the amount of noble metal used to lower the cost of the electrocatalyst. A common approach is to disperse noble metals in clusters or even as single atoms on the surface of acid-resistant non-noble metal oxides to reduce the amount of noble metal used. However, the stability of such acidic oxygen-generating electrocatalysts decreases rapidly with the dissolution of the noble metal. Therefore, in terms of existing technology, the three core issues of activity, stability, and noble metal loading of acidic oxygen-generating electrocatalysts cannot be well addressed, and research on electrocatalyst design in this area is still lacking. Summary of the Invention

[0004] The purpose of this invention is to provide an iridium cobalt oxide electrocatalyst with low noble metal loading, high efficiency and stability, suitable for large-scale production, as well as its preparation method and application, to solve the problems of high noble metal loading, low activity and low stability in existing acidic oxygen-generating electrocatalysts.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an iridium cobalt oxide electrocatalyst includes the following steps:

[0007] The cobalt-containing electrolyte was heated, and the washed Ti fiber felt was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode. A constant current was applied to electrodeposit metallic cobalt onto the Ti fiber felt.

[0008] Ti fiber felt electrodeposited with metallic cobalt was placed in an aqueous solution of IrCl3 and subjected to an electrochemical displacement reaction under heating, followed by calcination to obtain an iridium cobalt oxide electrocatalyst.

[0009] Furthermore, the cobalt-containing electrolyte is prepared by the following process: adding CoCl2·6H2O, H3BO3 and NH4Cl to deionized water, heating until dissolved, and adjusting the pH to 3-5 to obtain the electrolyte;

[0010] Furthermore, the ratio of deionized water, CoCl2·6H2O, H3BO3 to NH4Cl is 50–100 mL: 5–10 g: 1.75–3.5 g: 10–20 g.

[0011] Furthermore, the cobalt-containing electrolyte is heated to a temperature of 60–70°C.

[0012] Furthermore, the current density of the constant current is 50–100 mA cm⁻¹. -2 The electrodeposition time is 60–120 s.

[0013] Furthermore, the concentration of the IrCl3 aqueous solution is 1–5 mmol / L.

[0014] Furthermore, the electrochemical displacement reaction is carried out at a temperature of 60–70 °C for a time of 0.5–3 h.

[0015] Furthermore, the calcination temperature is 250–350℃, and the time is 1–2 hours.

[0016] Furthermore, the H2SO4 concentration was 0.1–1 mol / L, and the soaking time was 0.3–2 h.

[0017] An iridium cobalt oxide electrocatalyst prepared by the method described above, at a current density of 10 mA cm⁻¹ -2At a given voltage of 1.53V, the overpotential of the iridium cobalt oxide electrocatalyst is 252mV; at a given voltage of 1.53V... vs.RHE At that time, the mass activity was 0.34A mg. -1 Ir; at a current density of 200 mA cm -2 At that time, the stability was over 120 hours.

[0018] Application of an iridium cobalt oxide electrocatalyst as described above in the electrolysis of acidic water.

[0019] Compared with existing technologies, the present invention has the following advantages:

[0020] This invention employs an electrochemical displacement reaction method, through the reaction of reducing metals... Introducing high oxidation potential to the surface Driven by the thermodynamic difference between the two, an electrochemical displacement reaction occurs on the surface of metallic Co, where some Co is replaced by Ir, thus altering the Ir content. 3+ The concentration and reaction time can regulate the coordination environment around Ir, thereby affecting the activity and stability of the oxygen production process. In this invention, metallic Co is first electrodeposited on Ti fiber felt, and then placed on Ir... 3+ In solution, an electrochemical displacement reaction driven by the potential difference between two metals successfully deposited the noble metal Ir onto the surface of metallic Co. Finally, calcination in air yielded an iridium-cobalt oxide electrocatalyst. This invention modifies the noble metal Ir... 3+ Concentration, reaction time, and temperature control the electrochemical displacement reaction process, thereby influencing the coordination environment of the noble metal active sites and ultimately obtaining a low-noble-metal-loading, highly efficient, and stable iridium-cobalt oxide electrocatalyst for acidic oxygen production. The iridium-cobalt oxide prepared in this invention is self-supported and grown on the surface of Ti fiber mat, maintaining full contact with the Ti fiber mat without the need for additional binders, thus achieving rapid charge transfer and improving the catalyst's structural stability. This preparation method is simple, rapid, low-cost, and suitable for large-scale production.

[0021] Furthermore, the present invention uses a low amount of precious metals and has a simple preparation process, which can obtain a highly active and stable acidic oxygen-generating electrocatalyst in just a few hours, making it suitable for large-scale industrial production.

[0022] Electrolysis tests successfully constructed a highly efficient and stable iridium-cobalt oxide catalyst as an oxygen-generating active center on the surface. This catalyst operates at a current density of 10 mA cm⁻¹. -2 At that time, the overpotential was 252mV; at a voltage of 1.53V... vs.RHE At that time, the mass activity was 0.34A mg. -1 Ir At a current density of 200 mA cm -2At that time, the stability was above 120h, which solved the problems of high noble metal loading, low activity and low stability of acidic oxygen-generating electrocatalysts in the prior art. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0024] Figure 1 The X-ray diffraction pattern of the iridium cobalt oxide obtained in Example 1 of this invention;

[0025] Figure 2 These are scanning electron microscope images of iridium cobalt oxide obtained in Example 1 of the present invention; wherein (a) is at low magnification and (b) is at high magnification.

[0026] Figure 3 The images show X-ray photoelectron spectra of iridium cobalt oxide obtained in Example 1 of this invention; (a) is Ir, (b) is Co, and (c) is O.

[0027] Figure 4 The linear sweep voltammetric curve of the iridium cobalt oxide obtained in Example 1 of this invention;

[0028] Figure 5 The noble metal loading and mass activity of the iridium cobalt oxide obtained in Example 1 of this invention;

[0029] Figure 6 The overpotential-time curve of the iridium cobalt oxide obtained in Example 1 of this invention;

[0030] Figure 7 The linear sweep voltammetric curve of the iridium cobalt oxide obtained in Example 2 of this invention;

[0031] Figure 8 The linear sweep voltammetric curve of the iridium cobalt oxide obtained in Example 3 of this invention;

[0032] Figure 9 The linear sweep voltammetric curve of the iridium cobalt oxide obtained in Example 4 of this invention;

[0033] Figure 10 This is the linear sweep voltammetric curve of the iridium cobalt oxide obtained in Example 5 of the present invention. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0035] This invention aims to provide a method for preparing an iridium cobalt oxide electrocatalyst for use in an acidic water electrolysis reaction with low noble metal loading and high efficiency and stability. This invention utilizes an electrochemical displacement reaction method, by altering the noble metal Ir... 3+ By controlling the coordination environment of noble metal active sites through concentration and reaction time, a highly efficient and stable iridium-cobalt oxide was successfully constructed on the surface as an oxygen-generating active center, solving the problems of high noble metal loading, low activity, and low stability in existing acidic oxygen-generating electrocatalysts. This method is not only simple in process and requires less noble metal, but also ensures excellent activity and stability of the electrocatalyst, making it highly significant for large-scale production.

[0036] The preparation method of the iridium cobalt oxide electrocatalyst of the present invention includes the following steps:

[0037] Step 1) Preparation of electrolyte: Add 5-10g CoCl2·6H2O, 1.75-3.5g H3BO3, and 10-20g NH4Cl to 50-100mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 3-5 using ammonia water to obtain the electrolyte;

[0038] Step 2) Wash the Ti fiber felt: Cut to 0.5*0.5~1.0*1.0cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0039] Step 3) Apply electrodeposition: Take 20 mL to 40 mL of fresh electrolyte, heat and stir at 60 to 70 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 50 to 100 mA cm⁻¹ electrode for 60 to 120 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0040] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1-5 mmol / L and a volume of 5-10 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 60-70℃ for 0.5-3 h. Finally, take out the fiber felt and rinse it with deionized water.

[0041] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 250-350°C for 1-2 hours. After natural cooling, the catalyst is soaked in 0.1-1 mol / L H2SO4 solution for 0.3-2 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0042] The present invention is further illustrated by the following embodiments: The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the present invention as described in detail in the claims.

[0043] Example 1

[0044] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0045] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2 Ti fiber felt was washed sequentially with deionized water and anhydrous ethanol, then soaked in concentrated hydrochloric acid (11.6 mol / L), removed and rinsed with deionized water to complete the washing process.

[0046] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0047] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0048] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0049] Figure 1 This is the X-ray diffraction (XRD) pattern of the iridium-cobalt oxide in Example 1. Apart from the Ti fiber felt serving as the substrate, there are no diffraction peaks corresponding to IrO2 or Co3O4, indicating that the iridium and cobalt oxides are in an amorphous state.

[0050] Figure 2Images (a) and (b) are scanning electron microscope (SEM) images of the iridium cobalt oxide in Example 1. The electrocatalyst is densely grown on Ti fibers, exhibiting a cluster-like morphology encapsulated by nanosheets. Due to this unique morphology, the electrocatalyst and electrolyte are in full contact, which not only facilitates mass transfer but also provides a large number of active sites for oxygen production reactions.

[0051] Figure 3 Images (a), (b), and (c) are X-ray photoelectron spectroscopy (XPS) images of the iridium cobalt oxide in Example 1, corresponding to the Ir 4f, Co 2p, and O 1s peaks, respectively, indicating that Ir... 3+ An electrochemical displacement reaction did indeed occur between Ir and Co, and Ir was successfully introduced onto the Co surface.

[0052] Application of the above-mentioned iridium cobalt oxide electrocatalyst in acidic water electrolysis: The iridium cobalt oxide electrocatalyst prepared above was used as the working electrode and placed in a three-electrode system for performance testing. The counter electrode was a carbon rod, the reference electrode was Hg / Hg2SO4, and the electrolyte was a 0.5 mol / L H2SO4 solution.

[0053] Figure 4 This is the linear sweep voltammetry (LSV) curve corresponding to the iridium cobalt oxide in Example 1, with a scan rate of 5 mV / s and IR compensation of 90% (the IR compensation values ​​thereafter are all the same). The current density is 10 mA cm⁻¹. -2 At this location, the overpotential of the electrocatalyst is 252 mV.

[0054] Figure 5 The loading and mass activity of the noble metal Ir corresponding to this electrocatalyst are 290 μg cm⁻¹. -2 Ir The voltage is 1.53V. vs.RHE At that time, the mass activity was 0.34A mg. -1 Ir It not only has a low loading of precious metal Ir, but also has high quality activity.

[0055] Figure 6 This is a stability test, conducted at a current density of 200 mA cm⁻¹. -2 Under these conditions, the electrocatalyst can operate stably for 120 hours, with only a 50mV overpotential increase.

[0056] The above electrochemical performance tests demonstrate that by regulating the coordination environment of the noble metal active sites through electrochemical displacement reactions, a highly efficient and stable iridium-cobalt oxide was successfully constructed on the surface as an oxygen-generating active center, solving the problems of high noble metal loading, low activity, and low stability in existing acidic oxygen-generating electrocatalysts.

[0057] Example 2

[0058] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0059] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0060] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0061] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0062] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 2 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0063] Figure 7 This is the LSV curve corresponding to the iridium cobalt oxide electrocatalyst in Example 2, at a current density of 10 mA cm⁻¹. -2 At the same location as in Example 1, the overpotential of this electrocatalyst is 252 mV. This indicates that further increasing the soaking time to 2 h during the removal of unstable Co species from the surface does not significantly contribute to the activity.

[0064] Example 3

[0065] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0066] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0067] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 120 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0068] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0069] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 2 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0070] Figure 8 This is the LSV curve corresponding to the iridium cobalt oxide electrocatalyst in Example 3, at a current density of 10 mA cm⁻¹. -2 At the same location, the overpotential of the electrocatalyst is basically the same as that in Example 1, which is 253 mV. Increasing the total amount of metallic Co by increasing the electrodeposition time does not have a significant impact on the activity, indicating that Co does not act as an active site in the oxygen production reaction.

[0071] Example 4

[0072] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0073] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0074] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0075] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in Ti fiber felt with metallic cobalt electrodeposited on it. React at a temperature of 65℃ for 3 h. Finally, take out the fiber felt and rinse it with deionized water.

[0076] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0077] Figure 9 This is the LSV curve corresponding to the iridium cobalt oxide electrocatalyst in Example 4, at a current density of 10 mA cm⁻¹. -2 At the same location, compared to Example 1, the overpotential of this electrocatalyst was significantly reduced to 233 mV. This indicates that extending the electrochemical displacement reaction time to 3 hours, resulting in more Ir active sites deposited on the surface, is beneficial for increasing activity, but the corresponding mass activity decreases slightly at a voltage of 1.53 V. vs.RHE At that time, the mass activity was only 0.33A mg. -1 Ir .

[0078] Example 5

[0079] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0080] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0081] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0082] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0083] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 350°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0084] Figure 10 This is the LSV curve corresponding to the iridium cobalt oxide electrocatalyst in Example 5, at a current density of 10 mA cm⁻¹. -2 At the same location, the overpotential of the electrocatalyst was essentially the same as in Example 1, at 255 mV. This indicates that further increasing the temperature to 350 °C did not contribute to the activity, while a calcination temperature of 300 °C was sufficient for the electrocatalyst to convert into oxides.

[0085] Example 6

[0086] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 100mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0087] Step 2) Wash Ti fiber felt: Cut 1*1cm 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0088] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0089] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0090] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0091] Example 7

[0092] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0093] Step 2) Wash Ti fiber felt: Cut 1*1cm 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0094] Step 3) Electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 60 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 50 mA cm⁻¹ electrode for 60 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0095] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 1.3 mmol / L and a volume of 5 mL and place it in a container. Then put in a Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 65℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0096] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0097] Example 8

[0098] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0099] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0100] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 65 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0101] Step 4) Electrochemical displacement reaction: Take 10 mL of IrCl3 aqueous solution with a concentration of 5 mmol / L and place it in a container, then put in Ti fiber felt with metallic cobalt electrodeposited on it, react at 65℃ for 0.5 h, and finally take out the fiber felt and rinse it with deionized water.

[0102] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 2 hours. After natural cooling, the catalyst is soaked in 0.5 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0103] Example 9

[0104] Step 1) Preparation of electrolyte: Add 5g CoCl2·6H2O, 1.75g ​​H3BO3 and 10g NH4Cl to 50mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0105] Step 2) Wash the Ti fiber felt: Cut to 0.9*0.9cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0106] Step 3) Apply electrodeposition: Take 20 mL of fresh electrolyte, heat and stir at 70 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 90 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0107] Step 4) Electrochemical displacement reaction: Take 1.3 mol / L IrCl3 aqueous solution with a volume of 5 mL and place it in a container. Then put in Ti fiber felt with metallic cobalt electrodeposited on it. React at 70℃ for 0.5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0108] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 250°C for 1 hour. After natural cooling, the catalyst is soaked in 1 mol / L H2SO4 solution for 0.33 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0109] Example 10

[0110] Step 1) Preparation of electrolyte: Add 7g CoCl2·6H2O, 3g H3BO3 and 12g NH4Cl to 70mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 3 with ammonia water to obtain the electrolyte;

[0111] Step 2) Wash Ti fiber felt: Cut to 0.5*0.5cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0112] Step 3) Electrodeposition: Take 30 mL of fresh electrolyte, heat and stir at 60 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 90 mA cm⁻¹ electrode for 60 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0113] Step 4) Electrochemical displacement reaction: Take 1 mol / L IrCl3 aqueous solution with a volume of 6 mL and place it in a container. Then put in Ti fiber felt with metal cobalt electrodeposited on it. React at 60℃ for 1 h. Finally, take out the fiber felt and rinse it with deionized water.

[0114] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 250°C for 2 hours. After natural cooling, the catalyst is soaked in 0.1 mol / L H2SO4 solution for 2 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0115] Example 11

[0116] Step 1) Preparation of electrolyte: Add 9g CoCl2·6H2O, 3.5g H3BO3 and 15g NH4Cl to 80mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0117] Step 2) Wash Ti fiber felt: Cut 0.6*0.6cm pieces 2Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0118] Step 3) Electrodeposition: Take 40 mL of fresh electrolyte, heat and stir at 63 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 60 mA cm⁻¹ electrode for 80 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0119] Step 4) Electrochemical displacement reaction: Take an IrCl3 aqueous solution with a concentration of 4 mol / L and a volume of 8 mL and place it in a container. Then put in Ti fiber felt with cobalt metal electrodeposited on it. React at a temperature of 70℃ for 3 h. Finally, take out the fiber felt and rinse it with deionized water.

[0120] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 300°C for 1 hour. After natural cooling, the catalyst is soaked in 0.7 mol / L H2SO4 solution for 0.5 hours to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0121] Example 12

[0122] Step 1) Preparation of electrolyte: Add 8g CoCl2·6H2O, 2g H3BO3 and 18g NH4Cl to 90mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 5 with ammonia water to obtain the electrolyte;

[0123] Step 2) Wash the Ti fiber felt: Cut to 0.7*0.7cm. 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0124] Step 3) Electrodeposition: Take 25 mL of fresh electrolyte, heat and stir at 670 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 50 mA cm⁻¹ electrode for 120 s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0125] Step 4) Electrochemical displacement reaction: Take 3 mol / L IrCl3 aqueous solution with a volume of 9 mL and place it in a container. Then put Ti fiber felt with metallic cobalt electrodeposited on it into the container. React at 67℃ for 5 h. Finally, take out the fiber felt and rinse it with deionized water.

[0126] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 270°C for 1.5 hours. After natural cooling, the catalyst is soaked in 0.3 mol / L H2SO4 solution for 1 hour to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0127] Example 13

[0128] Step 1) Preparation of electrolyte: Add 10g CoCl2·6H2O, 2.5g H3BO3 and 20g NH4Cl to 60mL of deionized water, heat and stir until completely dissolved, and adjust the pH to 4 with ammonia water to obtain the electrolyte;

[0129] Step 2) Wash Ti fiber felt: Cut to 0.8*0.8cm 2 Ti fiber felt was washed with deionized water and anhydrous ethanol in sequence, then soaked in concentrated hydrochloric acid, removed and rinsed with deionized water to complete the washing process.

[0130] Step 3) Electrodeposition: Take 35 mL of fresh electrolyte, heat and stir at 70 °C, using the washed Ti fiber felt as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode, and apply a 100 mA cm⁻¹ electrode for 10⁵ s. -2 Constant current was used to achieve cobalt electrodeposition onto Ti fiber mat;

[0131] Step 4) Electrochemical displacement reaction: Take 10 mL of 2 mol / L IrCl3 aqueous solution and place it in a container. Then put in Ti fiber felt with cobalt metal electrodeposited on it. React at 63℃ for 2 h. Finally, take out the fiber felt and rinse it with deionized water.

[0132] Step 5) Calcination: The catalyst that has completed the electrochemical displacement reaction is placed in a muffle furnace and calcined in air at 280°C for 1.5 h. After natural cooling, the catalyst is soaked in 1 mol / L H2SO4 solution for 0.3 h to remove unstable species on the surface, and finally the iridium cobalt oxide electrocatalyst is obtained.

[0133] This invention utilizes an electrochemical displacement reaction to synthesize iridium cobalt oxide electrocatalysts simply and conveniently, by altering the noble metal Ir. 3+ By controlling the coordination environment of the noble metal active sites through concentration and reaction time, a highly efficient and stable iridium-cobalt oxide was successfully constructed on the surface as an oxygen-generating active center. This catalyst operates at a current density of 10 mA cm⁻¹. -2 At that time, the overpotential was 252mV; at a voltage of 1.53V... vs.RHE At that time, the mass activity was 0.34A mg. -1 IrAt a current density of 200 mA cm -2 At that time, the stability was above 120h, which solved the problems of high precious metal loading, low activity and low stability of acidic oxygen-generating electrocatalysts in the prior art, and provided a simple, fast, low-cost and efficient solution for industrial-scale production.

Claims

1. A method for preparing an iridium cobalt oxide electrocatalyst, characterized in that, Includes the following steps: The cobalt-containing electrolyte was heated, and the washed Ti fiber felt was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the carbon rod as the counter electrode. A constant current was applied to electrodeposit metallic cobalt onto the Ti fiber felt. Ti fiber felt electrodeposited with metallic cobalt was placed in an aqueous solution of IrCl3 and subjected to an electrochemical displacement reaction under heating, followed by calcination to obtain an iridium cobalt oxide electrocatalyst. Among them, the electrochemical displacement reaction introduces Ir with a high oxidation potential to the surface of reducing metal Co. 3+ The noble metal Ir was deposited onto the surface of metal Co by using an electrochemical displacement reaction driven by the potential difference between the two metals. The prepared iridium cobalt oxide electrocatalyst is self-supported and grown on the surface of Ti fiber mat, with full contact between it and the Ti fiber mat.

2. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, Cobalt-containing electrolytes are prepared by the following process: adding CoCl2·6H2O, H3BO3 and NH4Cl to deionized water, heating until dissolved, and adjusting the pH to 3-5 to obtain the electrolyte.

3. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 2, characterized in that, The ratio of deionized water, CoCl2·6H2O, H3BO3 to NH4Cl is 50~100 mL: 5~10 g: 1.75~3.5 g: 10~20 g.

4. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, The cobalt-containing electrolyte is heated to a temperature of 60-70 °C.

5. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, The current density of the constant current is 50~100 mA cm⁻¹ -2 The electrodeposition time is 60~120 s.

6. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, The concentration of IrCl3 aqueous solution is 1~5 mmol / L.

7. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, The electrochemical displacement reaction is carried out at a temperature of 60–70 °C for 0.5–3 h.

8. The method for preparing an iridium cobalt oxide electrocatalyst according to claim 1, characterized in that, The calcination temperature is 250~350 °C, and the time is 1~2 h.

9. An iridium cobalt oxide electrocatalyst prepared according to any one of claims 1-8, characterized in that, At a current density of 10 mA cm⁻¹ -2 At a given voltage of 1.53V, the overpotential of the iridium cobalt oxide electrocatalyst is 252 mV; at a given voltage of 1.53V... vs.RHE At that time, the mass activity was 0.34 A mg. -1 Ir; at a current density of 200 mA cm⁻¹ -2 At that time, the stability was above 120 h.

10. The application of the iridium cobalt oxide electrocatalyst as described in claim 9 in the electrolysis of acidic water.

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