Iridium manganese oxide catalyst for hydrogen production through water electrolysis as well as preparation method and application of iridium manganese oxide catalyst

Abstract

The invention relates to the technical field of water electrolysis hydrogen production catalysts, in particular to an iridium manganese oxide catalyst for water electrolysis hydrogen production and a preparation method and application of the iridium manganese oxide catalyst. According to the preparation method of the iridium manganese oxide catalyst, in an acidic aqueous solution environment, citric acid reacts with metal ions in chloroiridic acid hydrate and manganese salt to form a chelate; the Ir0. 2MnxO0. 3 nano-particles with the rutile type structure are prepared by performing a polyesterification reaction with ethylene glycol to form a metal salt precursor with a three-dimensional space grid structure, and performing drying treatment, high-temperature sintering and post-treatment on the metal salt precursor with the three-dimensional space grid structure. And the bonding strength of the iridium active site and the oxygen intermediate is optimized to ensure that the reaction energy barrier is reduced, so that the reaction energy barrier of the acidic electrolyzed water OER is reduced, the electro-catalysis hydrogen production performance is improved, and efficient and stable acidic electrolyzed water hydrogen production is realized. And the preparation method is simple, low in cost and easy for large-scale preparation. The catalyst has a good application prospect in oxygen evolution reaction in hydrogen production through acidic water decomposition.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts for producing hydrogen by electrolysis of water, and in particular to an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, and a preparation method and application thereof. Background Art

[0002] As an environmentally friendly and renewable energy with high calorific value, hydrogen energy is regarded as a key component of future energy. Hydrogen production through renewable energy power generation has low energy consumption, less greenhouse gas release during the preparation process, and the produced hydrogen is of high purity and low impurity content.

[0003] Among them, the most commonly used method for producing hydrogen by generating electricity from renewable energy is water electrolysis. However, in the prior art, the anode catalyst used for water electrolysis is expensive and has a low output, which limits its large-scale commercial application due to the high cost factor. In addition, in the water electrolysis hydrogen production technology, alkaline water decomposition (ALK) technology is mature and fully industrialized, but its strong corrosiveness to equipment and its poor dynamic response ability make it impossible to fully combine with various new energy power generation equipment. Water electrolysis hydrogen production such as solid polymer anion exchange membrane electrolysis (AEM) and high-temperature solid oxide electrolysis (SOEC) are still in the laboratory stage. Proton exchange membrane electrolysis (PEW) hydrogen production technology has high current density, high energy conversion efficiency, high hydrogen purity, small footprint, and better dynamic response speed, making it gradually become an important direction for the development and application of hydrogen production.

[0004] Commonly used anode catalysts for hydrogen production by proton exchange membrane electrolysis are IrO2 and RuO2. Among them, RuO2 has high activity in the OER of acidic water electrolysis, but its stability is poor. Due to its good activity and stability in the OER of acidic water electrolysis, IrO2 has been commercialized. However, the small reserves and output of iridium make IrO2 expensive, which prevents IrO2 from being commercialized on a large scale. In recent years, researchers have tried to further optimize the activity and stability of IrO2 to reduce the iridium loading through strategies such as heterojunction, strengthening the interaction between catalyst and carrier, and introducing defects. However, the synthesis process is difficult to control and it is difficult to commercialize on a large scale, which has hindered its research process to a certain extent. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the first object of the present invention is to provide an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, which achieves improved catalytic activity and stability, thereby improving the electrocatalytic hydrogen production performance.

[0006] In order to overcome the shortcomings of the prior art, the second object of the present invention is to provide a method for preparing an iridium manganese oxide catalyst for electrolyzing water to produce hydrogen, the preparation method having the advantages of simple preparation method, low cost, and easy large-scale preparation, and the prepared iridium manganese oxide catalyst has the advantages of high catalytic activity, good stability, and low cost.

[0007] The third object of the present invention is to provide an application of an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water in an oxygen evolution reaction in producing hydrogen by acidic water decomposition.

[0008] In order to achieve the first object of the above invention, the technical solution adopted by the present invention is as follows:

[0009] The present invention provides an iridium manganese oxide catalyst for electrolyzing water to produce hydrogen, which is an iridium manganese oxide catalyst having a rutile structure. 0.2 Mn x O 0.3 Nanoparticles, wherein the values ​​of x are 0.1, 0.2, 0.3 and 0.4.

[0010] Furthermore, the Ir 0.2 Mn x O 0.3 The molar percentages of the elements in the nanoparticles are: 28% Ir;

[0011] When x is 0.1, 14% Mn and 58% O;

[0012] When x is 0.2, 28% Mn and 44% O;

[0013] When x is 0.3, 42% Mn and 30% O;

[0014] When x is 0.4, it is 56% Mn and 16% O.

[0015] In order to achieve the second purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0016] The present invention provides a method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, comprising the following steps:

[0017] S1. preparing a metal salt precursor: adding ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt into an acidic aqueous solution to form a reaction system, and then heating the system to obtain a metal salt precursor;

[0018] S2, drying and high-temperature sintering: drying the metal salt precursor obtained in step S1, cooling it to room temperature, sintering it at high temperature, and then cooling it to room temperature to obtain a crude product;

[0019] S3, post-treatment: acid-washing, water-washing, centrifugation, filtering and heating and drying the crude product to obtain the iridium manganese oxide catalyst for hydrogen production by electrolysis of water.

[0020] Among them, the preparation method of an iridium manganese oxide catalyst for electrolysis of water for hydrogen production of the present invention is that in an acidic aqueous solution environment, citric acid reacts with chloroiridic acid hydrate and metal ions in manganese salt to form a chelate, and then the formed chelate is polyesterified with ethylene glycol to form a stable transparent sol system in the acidic aqueous solution, and the aged colloid particles slowly polymerize to form a three-dimensional space grid structure, and the network is filled with solvents that have lost fluidity to form a gel-like metal salt precursor. The gel-like metal salt precursor is dried and sintered at high temperature to obtain a crude product, and the crude product is acid-washed and washed with water to remove impurities, and centrifuged and dried to obtain Ir with a rutile structure. 0.2 Mn 0.1 O 0.3 Nanoparticles.

[0021] In addition, the entire reaction system of the present invention is an acidic aqueous solution. The role of the acidic aqueous solution as a reaction medium is to adjust the pH value of the reaction system, thereby promoting the reaction of citric acid with metal ions to form a chelate, and promoting the polyesterification reaction of the chelate and ethylene glycol to obtain a catalyst.

[0022] Furthermore, in step S1, the acidic aqueous solution is an aqueous solution of hydrochloric acid or acetic acid; and / or

[0023] The pH value of the reaction system is 0 to 2. This pH range can well promote the reaction of citric acid with metal ions to form a chelate, and promote the polyesterification reaction of the chelate with ethylene glycol to obtain a catalyst. If the pH value of the reaction system is greater than 2, the chloroiridic acid hydrate will be easily hydrolyzed, and if the pH value of the reaction system is greater than 4, the manganese salt will also be hydrolyzed, thereby affecting the progress of the entire reaction and hindering the synthesis of the catalyst.

[0024] Further, in step S1, the chloroiridic acid hydrate is chloroiridic acid hexahydrate, and the manganese salt is at least one of manganese chloride tetrahydrate, manganese acetate tetrahydrate or manganese nitrate hexahydrate; and / or

[0025] Furthermore, in step S1, the molar ratio of ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt is (1.5-2.5):(7-9):(0.1-0.3):(0.1-0.4).

[0026] Further, in step S1, ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt are added to an acidic aqueous solution, and after ultrasonic stirring to disperse and mix the reactants to form a reaction system, the system is placed in an electric constant temperature oil bath for stirring and heating reaction to obtain a metal salt precursor; and / or

[0027] The temperature of the stirring and heating reaction is 85° C. to 95° C., and the time of the stirring and heating reaction is 1.5 h to 2.5 h.

[0028] Among them, since the reaction between citric acid and ethylene glycol is relatively slow, the stirring operation during the stirring and heating reaction can promote the reaction between citric acid and metal ions to form a chelate, and promote the polyesterification reaction between the chelate and ethylene glycol.

[0029] Furthermore, in step S2, the drying treatment is to place the metal salt precursor in an electric heated air drying oven for drying, the drying temperature is 95° C. to 105° C., and the drying time is 13 h to 15 h.

[0030] Furthermore, in step S2, the high temperature sintering is to place the metal salt precursor cooled to room temperature after drying in a crucible, and then place it in a muffle furnace in an air atmosphere for high temperature sintering;

[0031] The high temperature sintering procedure in the muffle furnace is: first, the temperature is increased from room temperature to 250°C at a rate of 0.5°C / min to 1.5°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 350°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 400°C to 600°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; finally, the temperature is naturally reduced to room temperature to obtain a crude product.

[0032] Among them, in the high temperature sintering process in the muffle furnace, through slow heating and slow natural cooling annealing, a black powder solid catalyst with good crystallinity, uniform mixing and nanometer size can be obtained.

[0033] Further, in step S3, the acid washing reagent is 0.5M sulfuric acid, and the water washing reagent is ultrapure water; and / or

[0034] The acid washing and water washing times are 2 to 4 times respectively, and the centrifugation time is 4 to 6 minutes; and / or

[0035] The drying temperature is 55° C. to 65° C., and the drying time is 50 min to 70 min.

[0036] In order to achieve the third purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0037] The present invention provides an application of an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, and an application of the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water or the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared by the above-mentioned preparation method in an oxygen evolution reaction in hydrogen production by acidic water decomposition.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The iridium manganese oxide catalyst for hydrogen production by electrolysis of water of the present invention adopts a heteroatom doping control strategy to form an iridium manganese binary oxide by doping IrO2 with manganese. The crystal structure of manganese oxide is similar to that of IrO2. Therefore, manganese can be embedded in the crystal structure of IrO2 and redistribute and adjust the density of iridium active sites and electronic structure, thereby optimizing the binding strength between iridium active sites and oxygen intermediates to ensure that the reaction energy barrier is reduced, thereby reducing the reaction energy barrier of acidic water electrolysis OER, and finally improving Ir 0.2 Mn x O 0.3 The electrocatalytic oxygen evolution reaction performance of the nanoparticles can optimize and improve the catalytic activity and stability of IrO2, thereby improving the electrocatalytic hydrogen production performance and achieving efficient and stable hydrogen production by acidic water electrolysis.

[0040] (2) The present invention provides a method for preparing an iridium manganese oxide catalyst for electrolysis of water to produce hydrogen. In an acidic aqueous solution environment, citric acid reacts with chloroiridic acid hydrate and metal ions in a manganese salt to form a chelate, which is then polyesterified with ethylene glycol to form a metal salt precursor with a three-dimensional spatial grid structure. After drying, high-temperature sintering and post-treatment, an Ir with a rutile structure is obtained. 0.2 Mn x O 0.3 Nanoparticles. Therefore, the preparation method of the iridium manganese oxide catalyst for electrolysis of water to produce hydrogen has the advantages of simple method, low cost and easy large-scale preparation, and the prepared iridium manganese oxide catalyst has the advantages of high catalytic activity, good stability and low cost.

[0041] (3) Application of an iridium manganese oxide catalyst for hydrogen production by electrolysis of water of the present invention, application of the iridium manganese oxide catalyst for hydrogen production by electrolysis of water in the oxygen evolution reaction in the acidic water decomposition hydrogen production, can significantly improve the electrocatalytic activity and stability, and realize efficient and stable acidic water electrolysis hydrogen production, wherein the optimal overpotential in the application of the acidic water electrolysis oxygen evolution reaction is 245mV, and the stability is 2000h. In addition, the catalyst reduces its Ir loading while improving the catalytic activity, thereby significantly reducing the cost. Therefore, the iridium manganese oxide catalyst for hydrogen production by electrolysis of water prepared by the present invention has a good application prospect in the oxygen evolution reaction in the acidic water decomposition hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 This is the X-ray powder diffraction pattern of the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Examples 1-4 of the present invention.

[0044] Figure 2 The X-ray powder diffraction patterns of the iridium manganese oxide catalysts for producing hydrogen by electrolysis of water prepared in Examples 1 and 5 of the present invention and Comparative Example 3 are shown.

[0045] Figure 3 The X-ray powder diffraction pattern of the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Examples 1, 6 and 7 of the present invention.

[0046] Figure 4 Ir prepared in Example 1, Comparative Examples 1 and 2 of the present invention respectively 0.2 Mn 0.1 O 0.3 , IrO2, and Mn3O4.

[0047] Figure 5 Ir prepared in Example 1 of the present invention 0.2 Mn 0.1 O 0.3 High-resolution transmission electron microscopy image.

[0048] Figure 6 This is a high-resolution transmission electron microscope image of IrO2 prepared in Comparative Example 1 of the present invention.

[0049] Figure 7 Ir prepared in Example 1 of the present invention 0.2 Mn 0.1 O 0.3 Transmission electron microscopy energy scattering element distribution map.

[0050] Figure 8 This is a transmission electron microscope energy scattering element distribution diagram of IrO2 prepared in comparative example 1 of the present invention.

[0051] Fig. 9 Ir prepared in Examples 1-4 and Comparative Examples 1 and 2 of the present invention 0.2 Mn x O 0.3 , acidic OER activity diagram of IrO2 and Mn3O4.

[0052] Fig.10 The acidic OER activity diagram of the catalysts prepared in Examples 1 and 5 of the present invention and Comparative Example 3.

[0053] Fig.11 The acidic OER activity diagram of the catalysts prepared in Examples 1, 6, and 7 of the present invention.

[0054] Fig.12 Ir prepared in Example 1, Comparative Examples 1 and 2 of the present invention 0.2 Mn 0.1 O 0.3 , IrO2 and Mn3O4 in acidic OER stability diagram.

[0055] Fig.13 Ir prepared in Example 1 of the present invention 0.2 Mn 0.1 O 0.3 X-ray diffraction patterns of the samples before and after acidic OER. DETAILED DESCRIPTION

[0056] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. In the present invention, the singular forms "a", "said" and "the" used in the embodiments and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0058] Among them, the OER mentioned in the present invention refers to the electrocatalyst oxygen evolution reaction.

[0059] In the embodiment of the present invention, an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water is Ir 0.2 Mn x O 0.3 Nanoparticles, wherein the values ​​of x are 0.1, 0.2, 0.3 and 0.4.

[0060] Among them, Ir 0.2 Mn x O 0.3 The molar percentages of the elements in the nanoparticles are: 28% Ir;

[0061] When x is 0.1, 14% Mn and 58% O;

[0062] When x is 0.2, 28% Mn and 44% O;

[0063] When x is 0.3, 42% Mn and 30% O;

[0064] When x is 0.4, it is 56% Mn and 16% O.

[0065] In an embodiment of the present invention, a method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water comprises the following steps:

[0066] S1. preparing a metal salt precursor: adding ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt into an acidic aqueous solution to form a reaction system, and then heating the system to obtain a metal salt precursor;

[0067] S2, drying and high-temperature sintering: drying the metal salt precursor obtained in step S1, cooling it to room temperature, sintering it at high temperature, and then cooling it to room temperature to obtain a crude product;

[0068] S3, post-treatment: acid-washing, water-washing, centrifugation, filtering and heating and drying the crude product to obtain the iridium manganese oxide catalyst for hydrogen production by electrolysis of water.

[0069] In some embodiments, in step S1, the acidic aqueous solution is an aqueous solution of hydrochloric acid or acetic acid; and / or

[0070] The pH value of the reaction system is 0-2.

[0071] In some embodiments, in step S1, the chloroiridic acid hydrate is chloroiridic acid hexahydrate, and the manganese salt is at least one of manganese chloride tetrahydrate, manganese acetate tetrahydrate or manganese nitrate hexahydrate; and / or

[0072] In step S1, the molar ratio of ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt is (1.5-2.5):(7-9):(0.1-0.3):(0.1-0.4).

[0073] In some embodiments, in step S1, ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt are added to an acidic aqueous solution, and after ultrasonic stirring to disperse and mix the reactants to form a reaction system, the system is placed in an electric constant temperature oil bath for stirring and heating reaction to obtain a metal salt precursor; and / or

[0074] The temperature of the stirring and heating reaction is 85° C. to 95° C., and the time of the stirring and heating reaction is 1.5 h to 2.5 h.

[0075] In some embodiments, in step S2, the drying treatment is to place the metal salt precursor in an electric heated air drying oven for drying, the drying temperature is 95°C to 105°C, and the drying time is 13h to 15h.

[0076] In some embodiments, in step S2, the high temperature sintering is to place the metal salt precursor cooled to room temperature after drying in a crucible, and then place it in a muffle furnace in an air atmosphere for high temperature sintering;

[0077] The high temperature sintering procedure in the muffle furnace is: first, the temperature is increased from room temperature to 250°C at a rate of 0.5°C / min to 1.5°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 350°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 400°C to 600°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; finally, the temperature is naturally reduced to room temperature to obtain a crude product.

[0078] In some embodiments, in step S3, the acid washing reagent is 0.5M sulfuric acid, and the water washing reagent is ultrapure water; and / or

[0079] The acid washing and water washing times are 2 to 4 times respectively, and the centrifugation time is 4 to 6 minutes; and / or

[0080] The drying temperature is 55° C. to 65° C., and the drying time is 50 min to 70 min.

[0081] In an embodiment of the present invention, an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water is used, and the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water described above or the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared by the preparation method described above is used in the oxygen evolution reaction in the acidic water decomposition hydrogen production.

[0082] The following describes the invention in conjunction with specific embodiments.

[0083] Example 1

[0084] A method for preparing an iridium manganese oxide catalyst for electrolyzing water to produce hydrogen comprises the following steps: taking 8 mmol of citric acid, 2 mmol of ethylene glycol, 0.2 mmol of chloroiridic acid hexahydrate (H2IrCl6·6H2O) and 0.1 mmol of manganese chloride tetrahydrate (MnCl2·4H2O), adding them into a 50 mL beaker containing 20 mL of dilute HCl solution (a mixture of 10 mL of commercially available concentrated hydrochloric acid and 10 mL of ultrapure water), covering the beaker with a plastic wrap, heating it to 90 DEG C and stirring it for 2 hours, transferring the product into a crucible and placing the crucible into an electric heating blast drying oven for drying treatment, wherein the drying temperature is 100 DEG C and the drying time is 14 hours, and after the drying is completed and the temperature is cooled to room temperature, a colloidal solid mixture is obtained.

[0085] The crucible was transferred to a muffle furnace for high temperature treatment. The muffle furnace program was as follows: first, the temperature was increased from room temperature to 250°C at a rate of 1°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 350°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 450°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Finally, the crucible was taken out after it slowly cooled to room temperature to obtain a crude product.

[0086] The crude product was transferred to a centrifuge tube, and 10 mL of 0.5 M sulfuric acid solution was added for centrifugal solid-liquid separation. The supernatant was removed and the solid was retained. This step was repeated three times. Then 10 mL of ultrapure water was added for centrifugal solid-liquid separation. The supernatant was removed and the solid was retained. This step was repeated three times. Finally, the solid was transferred to an electric heating blast drying oven for drying at 60 ° C and 1 h. Finally, a black powder product was obtained, which was Ir with a rutile structure. 0.2 Mn 0.1 O 0.3 Nanoparticles are iridium manganese oxide catalysts used in the electrolysis of water to produce hydrogen.

[0087] Example 2

[0088] A method for preparing an iridium manganese oxide catalyst for electrolysis of water to produce hydrogen. The difference between this embodiment and embodiment 1 is that the amounts of iridium chloride hexahydrate and manganese chloride tetrahydrate added are 0.2 mmol and 0.2 mmol respectively. 0.2 Mn 0.2 O 0.3 Nanoparticles.

[0089] The rest of the methods in this embodiment are the same as those in Embodiment 1.

[0090] Example 3

[0091] A method for preparing an iridium manganese oxide catalyst for electrolysis of water to produce hydrogen. The difference between this embodiment and embodiment 1 is that the amounts of iridium chloride hexahydrate and manganese chloride tetrahydrate added are 0.2 mmol and 0.3 mmol, respectively, to obtain Ir 0.2 Mn 0.3 O 0.3 Nanoparticles.

[0092] The rest of the methods in this embodiment are the same as those in Embodiment 1.

[0093] Example 4

[0094] A method for preparing an iridium manganese oxide catalyst for electrolysis of water to produce hydrogen. The difference between this embodiment and embodiment 1 is that the amounts of iridium chloride hexahydrate and manganese chloride tetrahydrate added are 0.2 mmol and 0.4 mmol, respectively, to obtain Ir 0.2 Mn 0.4 O0.3 Nanoparticles.

[0095] The rest of the methods in this embodiment are the same as those in Embodiment 1.

[0096] Example 5

[0097] A method for preparing an iridium manganese oxide catalyst for electrolyzing water to produce hydrogen, the difference between this embodiment and embodiment 1 is that the muffle furnace procedure is: firstly, the temperature is increased from room temperature to 250°C at a rate of 1°C / min and then kept at that temperature for 1 hour, then the temperature is increased to 350°C at a rate of 10°C / min and then kept at that temperature for 1 hour, and then the temperature is increased to 600°C at a rate of 10°C / min and then kept at that temperature for 1 hour. The rest of the methods of this embodiment are the same as those of embodiment 1.

[0098] Example 6

[0099] A method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, the difference between this embodiment and embodiment 1 is that manganese acetate tetrahydrate (Mn(CH3COO)2·4H2O) is used to replace manganese chloride tetrahydrate. The rest of the methods of this embodiment are the same as those of embodiment 1.

[0100] Example 7

[0101] A method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, the difference between this embodiment and embodiment 1 is that manganese nitrate hexahydrate (Mn(NO3)2·6H2O) is used to replace manganese chloride tetrahydrate. The rest of the methods of this embodiment are the same as those of embodiment 1.

[0102] Comparative Example 1

[0103] A method for preparing an IrO2 catalyst for producing hydrogen by electrolyzing water comprises the following steps: taking 8 mmol of citric acid, 2 mmol of ethylene glycol and 0.2 mmol of chloroiridic acid hexahydrate and adding them into a 50 mL beaker containing 20 mL of dilute HCl solution (a mixture of 10 mL of commercially available concentrated hydrochloric acid and 10 mL of ultrapure water), covering the beaker with a plastic wrap and heating it to 90 DEG C and stirring it for 2 hours, transferring the product into a crucible and placing the crucible into an electric blast drying oven for drying treatment, wherein the drying temperature is 100 DEG C and the drying time is 14 hours, and after the drying is completed and the temperature is cooled to room temperature, a colloidal solid mixture is obtained.

[0104] The crucible was transferred to a muffle furnace for high temperature treatment. The muffle furnace program was as follows: first, the temperature was increased from room temperature to 250°C at a rate of 1°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 350°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 450°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Finally, the crucible was taken out after it slowly cooled to room temperature to obtain a crude product.

[0105] The crude product was transferred to a centrifuge tube, and 10 mL of 0.5 M sulfuric acid solution was added for centrifugal solid-liquid separation. The supernatant was removed and the solid was retained. This step was repeated three times. Then 10 mL of ultrapure water was added for centrifugal solid-liquid separation. The supernatant was removed and the solid was retained. This step was repeated three times. Finally, the solid was transferred to an electric heated blast drying oven for drying at 60 ° C and 1 h, and a black powder product IrO2 catalyst was finally obtained.

[0106] Comparative Example 2

[0107] A method for preparing a Mn3O4 catalyst for producing hydrogen by electrolyzing water comprises the following steps: taking 8mmol of citric acid, 2mmol of ethylene glycol and 0.1mmol of manganese chloride tetrahydrate and adding them into a 50mL beaker containing 20mL of dilute HCl solution (a mixture of 10mL of commercially available concentrated hydrochloric acid and 10mL of ultrapure water), covering the beaker with a plastic wrap and heating it to 90°C and stirring it for 2h, transferring the product into a crucible and placing the crucible into an electric heating blast drying oven for drying treatment, wherein the drying temperature is 100°C and the drying time is 14h, and after the drying is completed and the temperature is lowered to room temperature, a colloidal solid mixture is obtained.

[0108] The crucible was transferred to a muffle furnace for high temperature treatment. The muffle furnace program was as follows: first, the temperature was increased from room temperature to 250°C at a rate of 1°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 350°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Next, the temperature was increased to 450°C at a rate of 10°C / min and then kept at this temperature for 1 hour. Finally, the crucible was taken out after it slowly cooled to room temperature to obtain a crude product.

[0109] The crude product was transferred to a centrifuge tube, and 10 mL of 0.5 M sulfuric acid solution was added for centrifugal solid-liquid separation, and the supernatant was removed to leave the solid, and this step was repeated three times. Then 10 mL of ultrapure water was added for centrifugal solid-liquid separation, and the supernatant was removed to leave the solid, and this step was repeated three times. Finally, the solid was transferred to an electric heating blast drying oven for drying at a drying temperature of 60 ° C and a drying time of 1 h, and finally a brown product Mn3O4 catalyst was obtained.

[0110] Comparative Example 3

[0111] A method for preparing a catalyst for producing hydrogen by electrolyzing water. Compared with Example 1, the difference between this comparative example and Example 1 is that the muffle furnace procedure is: first, the temperature is increased from room temperature to 250°C at a rate of 1°C / min and then kept warm for 1 hour, and then the temperature is increased to 300°C at a rate of 10°C / min and then kept warm for 1 hour.

[0112] (I) X-ray diffraction analysis

[0113] The iridium manganese oxide catalysts for producing hydrogen by electrolysis of water prepared in Examples 1 to 7 and the catalysts prepared in Comparative Examples 1 to 3 were subjected to X-ray diffraction analysis (XRD), respectively. Figures 1 to 4 shown.

[0114] like Figure 1 As shown in the figure, the X-ray diffraction pattern shows that the Ir synthesized at a stoichiometric ratio of iridium chloride hexahydrate and manganese chloride tetrahydrate of 2:1 0.2 Mn 0.1 O 0.3 The catalyst has a rutile structure similar to that of IrO2 and is synthesized at stoichiometric ratios of 2:2, 2:3, and 2:4. 0.2 Mn 0.2 O 0.3 , Ir 0.2 Mn 0.3 O 0.3 , Ir 0.2 Mn 0.4 O 0.3 The catalyst crystal form is consistent and no phase change occurs. Therefore, it is shown that Mn doping does not change the Ir 0.2 Mn 0.1 O 0.3 Crystal structure of the catalyst.

[0115] like Figure 2 and Figure 3 As shown, the catalyst obtained by sintering at 300°C in Comparative Example 3 did not form a rutile structure. The catalysts obtained in Examples 5 to 7 were all the same as the Ir 0.2 Mn 0.1 O 0.3 The crystal structures of the catalysts are consistent. Figure 2 It is explained that the high temperature sintering temperature affects the crystallinity of the iridium manganese oxide catalyst used for electrolysis of water to produce hydrogen. Figure 3 It is explained that doping with different manganese sources will not change the crystal structure of the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water of the present invention.

[0116] like Figure 4 As shown, the X-ray diffraction patterns of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 indicate that the doping of manganese element does not destroy the original crystal structure of IrO2, and that the Mn element is successfully doped into the crystal lattice of IrO2.

[0117] (II) Morphological characterization by transmission electron microscopy

[0118] The iridium manganese oxide catalyst for hydrogen production by electrolysis of water prepared in Example 1 and the IrO2 catalyst for hydrogen production by electrolysis of water prepared in Comparative Example 1 were subjected to morphological characterization and energy scattering element distribution analysis by transmission electron microscopy (TEM), respectively. The analysis results are as follows: Figures 5 to 8 shown.

[0119] Depend on Figures 5 to 8 It can be seen that the three lattice fringes of 0.32nm, 0.26nm and 0.17nm all belong to the IrO2 catalyst for producing hydrogen by electrolysis of water prepared in Comparative Example 1. This shows that the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Example 1 has a significantly similar rutile structure as the IrO2 catalyst. It also shows that the three elements of Ir, O and Mn are uniformly distributed in the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in the present invention.

[0120] Among them, the element distribution of an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Example 1 and an IrO2 catalyst for producing hydrogen by electrolysis of water prepared in Comparative Example 1 are shown in Table 1.

[0121] Table 1 Element distribution of the catalysts of Example 1 and Comparative Example 1

[0122]

[0123] Figure 5-8 Together with Table 1, this shows the successful synthesis of iridium manganese oxide catalyst for hydrogen production by water electrolysis without changing the crystal structure of IrO2.

[0124] (III) Oxygen evolution reaction performance test of hydrogen production by acidic water electrolysis

[0125] The test method is as follows: Acidic water electrolysis OER is carried out in a 100mL electrolytic cell with a three-electrode system, which is connected to the atmospheric environment. Oxygen is introduced for 0.5h before the test to ensure that a saturated O2 solution is reached in the acidic electrolyte 0.5M sulfuric acid solution. 4mg of the catalyst is dispersed in a mixture of 500μL isopropanol, 40μLmL Nafion solution and 500μL ultrapure water, and it is subjected to ultrasonic treatment for 0.5h. 32μL of the homogeneous mixture after ultrasonication is transferred to the glassy carbon electrode with a pipette and dried with an infrared baking lamp to obtain a working electrode with a catalyst loading of 0.63mg / cm 2 Shanghai Chenhua electrochemical workstation, three-electrode system (reference electrode is Ag / AgCl (3.5MKCl), counter electrode is 1*1cm 2 The platinum sheet and the working electrode are catalysts with a loading of 0.63 mg / cm 2 , with an area of ​​0.196 cm 2The OER performance of water electrolysis was investigated using a glassy carbon electrode (glassy carbon electrode) in an acidic electrolyte (0.5 M sulfuric acid solution).

[0126] The OER activity of acidic water electrolysis was tested by linear sweep voltammetry, usually at a current density of 10 mA / cm 2 The overpotential value is used to judge the OER activity. The measurement voltage range is 1.1V-1.8V (vs. RHE). Since the theoretical minimum potential required for the OER reaction is 1.23V, the overpotential is the current density of 10mA / cm 2 The voltage value measured in the following experiment is the voltage value of the reference electrode (0.2046 V in this experiment) minus 1.23 V. The lower the overpotential, the higher the OER activity.

[0127] The stability test of acidic water electrolysis OER was carried out by chronopotentiometry, usually at a constant current density (10 mA / cm in this experiment). 2 ) to observe the duration of maintenance under a certain voltage range. The longer the maintenance time, the better the OER stability.

[0128] (1) Analysis of acidic OER activity

[0129] The catalysts prepared in Examples 1 to 7 and Comparative Examples 1 to 3 were respectively subjected to acidic OER activity analysis. The analysis results are as follows: Figures 9 to 11 shown.

[0130] Depend on Figures 9 to 11 It can be seen that the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Example 1 of the present invention has the best acidic OER activity.

[0131] (2) Acidic OER stability analysis

[0132] The iridium manganese oxide catalyst for hydrogen production by electrolysis of water prepared in Example 1, the IrO2 catalyst prepared in Comparative Example 1, and the Mn3O4 catalyst prepared in Comparative Example 2 were respectively subjected to acidic OER stability analysis. The analysis results are as follows: Fig.12 shown.

[0133] Depend on Fig.12 It can be seen that the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in Example 1 of the present invention has excellent stability compared with the catalysts of Comparative Examples 1 and 2.

[0134] In addition, the iridium manganese oxide catalyst for hydrogen production by electrolysis of water prepared in Example 1 was subjected to X-ray diffraction analysis before and after acidic OER. The analysis results are as follows: Fig.13 As shown. Fig.13It can be seen that the crystal structure of the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in the present invention remains basically unchanged after the acidic OER reaction, which further shows that the iridium manganese oxide catalyst for producing hydrogen by electrolysis of water prepared in the present invention has excellent stability.

[0135] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, characterized in that: Ir with rutile structure 0.2 Mn x O 0.3 Nanoparticles, wherein the values ​​of x are 0.1, 0.2, 0.3 and 0.

4.

2. The iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 1, characterized in that: The Ir 0.2 Mn x O 0.3 The molar percentages of the elements in the nanoparticles are: 28% Ir; When x is 0.1, 14% Mn and 58% O; When x is 0.2, 28% Mn and 44% O; When x is 0.3, 42% Mn and 30% O; When x is 0.4, it is 56% Mn and 16% O.

3. The method for preparing an iridium manganese oxide catalyst for hydrogen production from water according to any one of claims 1 or 2, characterized in that: The following steps are involved: S1. Preparing a metal salt precursor: adding ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt into an acidic aqueous solution to form a reaction system, and then heating the system to obtain a metal salt precursor; S2, drying and high-temperature sintering: drying the metal salt precursor obtained in step S1, cooling it to room temperature, and then sintering it at high temperature, and then cooling it to room temperature to obtain a crude product; S3, post-treatment: acid-washing, water-washing, centrifugation, filtering and heating and drying the crude product to obtain the iridium manganese oxide catalyst for hydrogen production by electrolysis of water.

4. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S1, the acidic aqueous solution is an aqueous solution of hydrochloric acid or acetic acid; and / or The pH value of the reaction system is 0-2.

5. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S1, the chloroiridic acid hydrate is chloroiridic acid hexahydrate, and the manganese salt is at least one of manganese chloride tetrahydrate, manganese acetate tetrahydrate or manganese nitrate hexahydrate; and / or In step S1, the molar ratio of ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt is (1.5-2.5):(7-9):(0.1-0.3):(0.1-0.4).

6. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S1, ethylene glycol, citric acid, chloroiridic acid hydrate and manganese salt are added to an acidic aqueous solution, and after ultrasonic stirring to disperse and mix the reactants to form a reaction system, the system is placed in an electric constant temperature oil bath for stirring and heating reaction to obtain a metal salt precursor; and / or The temperature of the stirring and heating reaction is 85° C. to 95° C., and the time of the stirring and heating reaction is 1.5 h to 2.5 h.

7. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S2, the drying treatment is to place the metal salt precursor in an electric heated air drying oven for drying, the drying temperature is 95°C to 105°C, and the drying time is 13h to 15h.

8. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S2, the high temperature sintering is to place the metal salt precursor cooled to room temperature after drying in a crucible, and then place it in a muffle furnace in an air atmosphere for high temperature sintering; The high temperature sintering procedure in the muffle furnace is: first, the temperature is increased from room temperature to 250°C at a rate of 0.5°C / min to 1.5°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 350°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; then, the temperature is increased to 400°C to 600°C at a rate of 9°C / min to 11°C / min, and then kept warm for 50min to 70min; finally, the temperature is naturally reduced to room temperature to obtain a crude product.

9. The method for preparing an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water as claimed in claim 3, characterized in that: In step S3, the acid washing reagent is 0.5M sulfuric acid, and the water washing reagent is ultrapure water; and / or The acid washing and water washing times are 2 to 4 times respectively, and the centrifugation time is 4 to 6 minutes; and / or The drying temperature is 55° C. to 65° C., and the drying time is 50 min to 70 min.

10. An application of an iridium manganese oxide catalyst for producing hydrogen by electrolysis of water, characterized in that: Application of the iridium manganese oxide catalyst for hydrogen production by electrolysis of water as claimed in claim 1 or 2 or the iridium manganese oxide catalyst for hydrogen production by electrolysis of water obtained by the preparation method according to any one of claims 3 to 9 in the oxygen evolution reaction in hydrogen production by acidic water decomposition.

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