Iridium ruthenium-based porous oxide catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of OER catalysts, in particular to an iridium ruthenium-based porous oxide catalyst and a preparation method and application thereof. The preparation method of the iridium-ruthenium-based porous oxide catalyst comprises the following steps: uniformly mixing an iridium source, a ruthenium source, low-electronegativity metal precursor salt, a pore forming agent, a surfactant and a solvent to obtain a precursor solution; performing heat treatment on the precursor solution to remove the solvent, and grinding to obtain precursor powder; and calcining the precursor powder in an air atmosphere to obtain the low-electronegativity metal doped iridium ruthenium-based porous oxide catalyst. The low-electronegativity element doped iridium ruthenium-based porous oxide catalyst is prepared by doping the low-electronegativity element, so that the stability of the catalyst can be greatly improved, an active center electron structure can be optimized, excessive oxidation precipitation of ruthenium is inhibited, and the catalytic activity of the catalyst is improved. The problems that iridium oxide needs very high overpotential to drive OER, ruthenium is very easy to oxidize and dissolve, and the long-term stability of the catalyst is easy to influence are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of OER catalysts, and particularly relates to an iridium-ruthenium-based porous oxide catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Water electrolysis is one of the most feasible hydrogen supply methods for establishing a clean and renewable energy cycle. Water electrolysis includes two half-cell reactions, namely the hydrogen evolution reaction at the cathode and the oxygen evolution reaction at the anode. The full English name of the hydrogen evolution reaction at the cathode is Hydrogen Evolution Reaction, abbreviated as HER; the full English name of the oxygen evolution reaction at the anode is Oxygen Evolution Reaction, abbreviated as OER. Compared with the hydrogen evolution reaction at the cathode, the oxygen evolution reaction at the anode involves the transfer of four protons and electrons for each oxygen molecule, and the kinetics is very slow, which is the key reaction restricting the performance of water electrolysis. Therefore, the development of efficient and stable OER catalysts is a difficult point and a hot spot in the field of water electrolysis.

[0003] Metal oxide catalysts have stronger oxygen evolution activity and stability under strong acid and oxidation conditions. Iridium oxide and ruthenium oxide are one of the most widely used materials for catalyzing OER at present. Although iridium oxide shows moderate oxygen evolution reaction stability in acidic media, a very high overpotential is still required to drive OER, generally exceeding 300 mV. In contrast, ruthenium has higher OER performance and is 5 to 16 times cheaper than iridium. However, ruthenium is extremely easy to be oxidized and dissolved, and it is difficult to maintain high activity under high potential operation, which will affect the long-term operation of the catalyst. Summary of the Invention

[0004] In order to solve the problems that iridium oxide requires a very high overpotential to drive OER, ruthenium is extremely easy to be oxidized and dissolved, and it is difficult to maintain high activity under high potential operation, thereby affecting the long-term stability of the catalyst, the purpose of the present invention is to provide an iridium-ruthenium-based porous oxide catalyst, a preparation method thereof, and an application thereof.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows.

[0006] The first aspect of the present invention provides a preparation method of an iridium-ruthenium-based porous oxide catalyst, comprising the following steps:

[0007] Mix an iridium source, a ruthenium source, a low electronegativity metal precursor salt, a pore former, a surfactant and a solvent uniformly to obtain a precursor solution; perform heat treatment on the precursor solution to remove the solvent, and grind to obtain a precursor powder; calcine the precursor powder in an air atmosphere to obtain a low electronegativity metal-doped iridium ruthenium-based porous oxide catalyst; the low electronegativity metal precursor salt is at least one of a chromium source, a manganese source, a yttrium source, a lanthanum source, a praseodymium source, a neodymium source, a samarium source, a gadolinium source and an erbium source; the pore former is at least one of glucose and fructose; the surfactant is at least one of urea, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride.

[0008] The present invention mainly uses low electronegativity elements in an iridium source, a ruthenium source and a low electronegativity metal precursor salt to dope and prepare a low electronegativity element-doped iridium ruthenium-based porous oxide catalyst, which can not only greatly improve the stability of the catalyst, but also further optimize the electronic structure of the catalyst, making it exhibit more excellent performance. The present invention makes up for the deficiencies of poor performance of iridium element, poor ruthenium stability, and inability to continuously and precisely adjust the binding energy by doping with iridium source, ruthenium source and low electronegativity elements.

[0009] The present invention can optimize the electronic structure of the active center by doping with low electronegativity elements, inhibit the excessive oxidation and precipitation of ruthenium, so as to reduce the overpotential of the iridium ruthenium-based porous oxide catalyst, exhibit efficient and stable oxygen evolution catalytic performance, and has potential commercial application prospects, solving the problems that iridium oxide requires a very high overpotential to drive OER and ruthenium is extremely easy to be oxidized and dissolved, and it is difficult to maintain high activity under high potential operation, thus affecting the long-term stability of the catalyst.

[0010] The pore former added in the present invention is selected from at least one of glucose and fructose; the surfactant is selected from at least one of urea, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride. The pore former adopted in the present invention decomposes and releases gases such as CO 2 、H 2 O at high temperature to form a three-dimensional porous carbon skeleton with a high specific surface area and abundant pores, significantly improving the exposure of active sites and mass transfer efficiency of the electrocatalyst. The surfactant can further make the catalyst form a porous foam-like structure. Among them, insufficient pore former will lead to poor catalyst performance, while insufficient surfactant will cause the prepared iridium ruthenium-based porous oxide catalyst not to form a porous foam-like structure.

[0011] Preferably, in the precursor solution, the concentration of the iridium source is 2 mg / mL to 9 mg / mL; the concentration of the ruthenium source is 1.5 mg / mL to 6 mg / mL; the concentration of the low electronegativity metal precursor salt is 0.5 mg / mL to 1.5 mg / mL; the concentration of the pore former is 1 mg / mL to 2 g / mL; the concentration of the surfactant is 100 mg / mL to 400 mg / mL.

[0012] In the present invention, the iridium source and the ruthenium source are doped with each other to adjust the binding energy to obtain better performance. The binding energy can be adjusted by changing the concentrations of iridium and ruthenium, but this adjustment method cannot continuously adjust. However, the low electronegativity element has the ability to continuously adjust the strength of the binding energy during the doping process, thereby more precisely controlling the binding energy.

[0013] In the present invention, the change in the concentration of the low electronegativity element will affect the performance of the catalyst. The results of subsequent experiments show that the concentration of the low electronegativity metal precursor salt is determined to be 0.5 mg / mL to 1.5 mg / mL, and the performance is optimal within this range.

[0014] By controlling conditions such as the type of auxiliary metal precursor, the concentration of the pore former, the reaction temperature, and the reaction time, the present invention can more precisely control the reaction kinetics of the formation process of the low electronegativity element-doped iridium ruthenium-based porous oxide. The reaction conditions are mild, the operation is simple, and the element composition of the prepared low electronegativity element-doped iridium ruthenium-based porous oxide is controllable, which is of great significance in the research of low-dimensional multi-metal alloys.

[0015] Preferably, the iridium source is iridium trichloride, iridium carbonyl, or iridium acetylacetonate; the ruthenium source is ruthenium trichloride, dodecacarbonyltriruthenium, or ruthenium acetylacetonate; the chromium source is chromium trichloride or chromium acetylacetonate; the manganese source is manganese chloride or manganese acetylacetonate; the yttrium source is yttrium chloride or yttrium nitrate; the lanthanum source is lanthanum chloride or lanthanum acetylacetonate; the praseodymium source is praseodymium chloride or praseodymium nitrate; the neodymium source is neodymium chloride or neodymium acetylacetonate; the promethium source is promethium chloride; the samarium source is samarium chloride; the gadolinium source is gadolinium chloride or gadolinium nitrate; the erbium source is erbium chloride or holmium nitrate.

[0016] Preferably, the solvent is at least one of water, ethanol, benzyl alcohol, and N,N-dimethylformamide.

[0017] Preferably, the calcination temperature is 400 °C to 1000 °C, and the calcination time is 6 hours to 12 hours. Preferably, the calcination temperature is 900 °C to 1000 °C, and the calcination time is 10 hours to 12 hours.

[0018] In the present invention, in order to make the catalyst form a porous foam structure, the calcination temperature should be controlled to reach 900 °C to 1000 °C as much as possible, and the calcination time should be controlled at about 10 hours. If the temperature is too low or the calcination time is insufficient, it will cause it to not be fully oxidized to form a porous foam structure. The subsequent experimental results show that when the temperature is too low or the calcination time is insufficient, a grayish-white porous solid will be formed, and its performance is poor compared with the product obtained by full calcination. The experimental results show that the performance of the product obtained at too high a temperature and too long a calcination time deteriorates. The reason is that when the temperature is too high and the calcination time is too long, it will cause the catalyst to be over-oxidized, and the valence state of ruthenium is easily raised to a valence state above +5.

[0019] Preferably, the heat treatment temperature is 100 °C to 200 °C. The heat treatment time is 8 hours to 10 hours.

[0020] In the second aspect of the present invention, an iridium-ruthenium-based porous oxide catalyst is provided, which is prepared by using the preparation method of the iridium-ruthenium-based porous oxide catalyst described in the first aspect.

[0021] Preferably, the particle size of the iridium-ruthenium-based porous oxide catalyst is 8 nm to 10 nm.

[0022] Preferably, the iridium-ruthenium-based porous oxide catalyst is obtained by doping a low electronegativity metal element into the iridium-ruthenium-based oxide; the molar percentage of the low electronegativity metal element in the iridium-ruthenium-based porous oxide catalyst is less than 10%.

[0023] In the present invention, in order to ensure that the performance of the product catalyst reaches the optimum, it is necessary to ensure that the molar percentage of the low electronegativity metal element in the iridium-ruthenium-based porous oxide catalyst is 5% to 10%. Among them, if the molar content of the low electronegativity metal element is too low, the performance improvement of the iridium-ruthenium-based porous oxide catalyst compared with the comparative sample IrRuOx is not significant; when the molar content of the low electronegativity metal element increases to more than 10%, the activity of the iridium-ruthenium-based porous oxide catalyst does not increase significantly, and the covalency of the ruthenium-oxygen bond in the iridium-ruthenium-based porous oxide catalyst is too low, which will cause the catalyst to quickly deactivate during operation at a high current density, and the stability is significantly reduced.

[0024] Preferably, in the iridium-ruthenium-based porous oxide catalyst, the molar ratio of iridium to ruthenium is 1:0.2 to 5.

[0025] In the third aspect of the present invention, an application of the iridium-ruthenium-based porous oxide catalyst described in the second aspect as an oxygen evolution catalyst for electrolytic water is provided.

[0026] The beneficial effects of the present invention:

[0027] 1. The present invention prepares an iridium-ruthenium-based porous oxide catalyst doped with low electronegativity elements. This not only greatly improves the stability of the catalyst but also optimizes the electronic structure of the active center, inhibits the excessive oxidation and precipitation of ruthenium, reduces the overpotential of the iridium-ruthenium-based porous oxide catalyst, exhibits efficient and stable oxygen evolution catalytic performance, and solves the problems that iridium oxide requires a very high overpotential to drive OER, ruthenium is extremely easy to be oxidized and dissolved, and it is difficult to maintain high activity under high potential operation, thus affecting the long-term stability of the catalyst.

[0028] 2. The overpotential of the iridium-ruthenium-based porous oxide catalyst doped with low electronegativity elements prepared by the present invention is 237 mV, which is 118 mV lower than that of the commercial IrO 2 catalyst.

[0029] 3. The preparation method of the present invention is simple in operation and convenient for large-scale preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a transmission electron microscope image of the Sm-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 1.

[0031] Figure 2 It is an X-ray diffraction pattern of the Mn-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 2, IrRuOx, ruthenium oxide and iridium oxide in Comparative Example 1.

[0032] Figure 3 It is a comparison diagram of the oxygen evolution reaction activity of the Mn-IrRuOx catalyst, La-IrRuOx catalyst and Gd-IrRuOx catalyst prepared in Examples 2 to 4 and the commercial IrO 2 catalyst under acidic conditions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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.

[0034] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] The present invention aims to design a structure of an iridium-ruthenium-based oxide catalyst to reduce the overpotential of the iridium-ruthenium-based oxide and improve the stability of the catalyst.

[0036] Heteroatom doping and oxygen vacancy construction can effectively regulate the local electronic structure and bonding environment, thereby affecting the structure and surface properties of materials, which is beneficial to improving the catalytic performance of catalysts. Based on this, the present invention develops an iridium-ruthenium-based porous oxide catalyst doped with low electronegativity elements. By doping low electronegativity elements into the iridium-ruthenium-based oxide, the present invention can not only greatly improve the stability of the catalyst, but also further optimize the electronic structure of the catalyst, making it exhibit more excellent performance.

[0037] The iridium-ruthenium-based porous oxide catalyst prepared by the present invention, due to the optimization of the electronic structure of the active center by doping with low electronegativity elements and the inhibition of the excessive oxidation and precipitation of ruthenium, exhibits efficient and stable oxygen evolution catalytic performance and has potential commercial application prospects. In particular, the Mn-IrRuOx catalyst prepared by the present invention has the best performance, with an overpotential of 237 mV, which is 118 mV higher than that of the commercial IrO 2 catalyst.

[0038] The technical solution of the present invention will be further described below through specific examples.

[0039] In the following examples, unless otherwise specified, the methods are all conventional methods; the reagents and materials, unless otherwise specified, can be purchased on the market.

[0040] Example 1

[0041] A preparation method of an iridium-ruthenium-based porous oxide catalyst includes the following steps:

[0042] Step 1, dissolve iridium trichloride, ruthenium trichloride, samarium chloride, glucose and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.1 mg / mL, 1000 mg / mL and 200 mg / mL respectively, and ultrasonicate for 20 minutes with an ultrasonic power of 60 W to form a turbid and uniform colloidal precursor dispersion.

[0043] Step 2, place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a dark brown porous foam; grind the porous foam to form a dark brown powder.

[0044] Step 3, transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 hours to obtain a Sm-doped iridium-ruthenium-based porous oxide catalyst, denoted as Sm-IrRuOx.

[0045] Example 2

[0046] A preparation method of an iridium-ruthenium-based porous oxide catalyst includes the following steps:

[0047] Step 1: Dissolve iridium(III) chloride, ruthenium(III) chloride, manganese(II) chloride, glucose, and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.2 mg / mL, 1000 mg / mL, and 200 mg / mL respectively, and ultrasonicate for 15 minutes at an ultrasonic power of 60 W to form a turbid and homogeneous colloidal precursor dispersion.

[0048] Step 2: Place the precursor dispersion in an oven at 140 °C and dry for 8 h to form a dark brown porous foam; grind the porous foam to form a dark brown powder.

[0049] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 hours to obtain a Mn-doped iridium-ruthenium-based porous oxide catalyst; denoted as Mn-IrRuOx.

[0050] Example 3

[0051] A preparation method of an iridium-ruthenium-based porous oxide catalyst, comprising the following steps:

[0052] Step 1: Dissolve iridium(III) chloride, ruthenium(III) chloride, lanthanum(III) chloride, glucose, and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.1 mg / mL, 1000 mg / mL, and 200 mg / mL respectively, and ultrasonicate for 20 minutes at an ultrasonic power of 60 W to form a turbid and homogeneous colloidal precursor dispersion.

[0053] Step 2: Place the precursor dispersion in an oven at 140 °C and dry for 8 h to form a dark brown porous foam; grind the porous foam to form a dark brown powder.

[0054] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 8 hours to obtain a gray foamy porous material.

[0055] Step 4: Grind the gray foamy porous material and heat it in a muffle furnace at 400 °C for 5 hours to obtain a black La-doped iridium-ruthenium-based porous oxide catalyst, denoted as La-IrRuOx.

[0056] Example 4

[0057] A preparation method of an iridium-ruthenium-based porous oxide catalyst, comprising the following steps:

[0058] Step 1: Dissolve iridium(III) chloride, ruthenium(III) chloride, gadolinium(III) chloride, glucose, and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.2 mg / mL, 1000 mg / mL, and 200 mg / mL respectively, and ultrasonicate for 15 minutes at an ultrasonic power of 60 W to form a turbid and homogeneous colloidal precursor dispersion.

[0059] Step 2: Place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a porous foam in dark brown; grind the porous foam to form a dark brown powder.

[0060] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 h to obtain a Gd-doped iridium ruthenium-based porous oxide catalyst; denoted as Gd-IrRuOx.

[0061] Comparative Example 1

[0062] A preparation method of an iridium ruthenium-based porous oxide catalyst, which is different from Example 1 in that no samarium doping is carried out. The specific method comprises the following steps:

[0063] Step 1: Dissolve iridium trichloride, ruthenium trichloride, glucose and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1000 mg / mL and 200 mg / mL respectively, and ultrasonicate for 20 minutes with an ultrasonic power of 60 W to form a turbid and uniform colloidal precursor dispersion.

[0064] Step 2: Place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a porous foam in dark brown; grind the porous foam to form a dark brown powder.

[0065] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 h to obtain an iridium ruthenium-based porous oxide catalyst, denoted as IrRuOx.

[0066] Comparative Example 2

[0067] A preparation method of an iridium ruthenium-based porous oxide catalyst, which is different from Example 1 in that the amount of samarium doping in the precursor is increased. The specific method comprises the following steps:

[0068] Step 1: Dissolve iridium trichloride, ruthenium trichloride, samarium chloride, glucose and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 3.3 mg / mL, 1000 mg / mL and 200 mg / mL respectively, and ultrasonicate for 20 minutes with an ultrasonic power of 60 W to form a turbid and uniform colloidal precursor dispersion.

[0069] Step 2: Place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a porous foam in dark brown; grind the porous foam to form a dark brown powder.

[0070] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 h to obtain an iridium ruthenium-based porous oxide catalyst, denoted as Sm3-IrRuOx.

[0071] Comparative Example 3

[0072] A preparation method of an iridium-ruthenium-based porous oxide catalyst, which is different from that of Example 1 in that the doping amount of the precursor samarium is reduced. The specific method comprises the following steps:

[0073] Step 1: Dissolve iridium trichloride, ruthenium trichloride, samarium chloride, glucose and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 0.5 mg / mL, 1000 mg / mL and 200 mg / mL respectively, and ultrasonicate for 20 minutes with an ultrasonic power of 60 W to form a turbid and uniform colloidal precursor dispersion.

[0074] Step 2: Place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a dark brown porous foam; grind the porous foam to form a dark brown powder.

[0075] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 hours to obtain an iridium-ruthenium-based porous oxide catalyst, denoted as Sm0.5-IrRuOx.

[0076] Comparative Example 4

[0077] A preparation method of an iridium-ruthenium-based porous oxide catalyst, which is different from that of Example 1 in that the glucose incorporation amount is halved. The specific method comprises the following steps:

[0078] Step 1: Dissolve iridium trichloride, ruthenium trichloride, samarium chloride, glucose and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.1 mg / mL, 500 mg / mL and 200 mg / mL respectively, and ultrasonicate for 20 minutes with an ultrasonic power of 60 W to form a turbid and uniform colloidal precursor dispersion.

[0079] Step 2: Place the precursor dispersion in an oven at 140 °C and dry it for 8 h to form a dark brown porous foam; grind the porous foam to form a brown powder.

[0080] Step 3: Transfer the brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 hours to obtain an iridium-ruthenium-based porous oxide catalyst, denoted as Sm-IrRuOx with halved glucose.

[0081] Comparative Example 5

[0082] A preparation method of an iridium-ruthenium-based porous oxide catalyst, which is different from that of Example 1 in that the amount of the surfactant urea incorporated is reduced. The specific method comprises the following steps:

[0083] Step 1: Dissolve iridium(III) chloride, ruthenium(III) chloride, samarium(III) chloride, glucose, and urea in water at concentrations of 5.7 mg / mL, 4 mg / mL, 1.1 mg / mL, 1000 mg / mL, and 100 mg / mL respectively, and ultrasonicate for 20 minutes at an ultrasonic power of 60 W to form a turbid and homogeneous colloidal precursor dispersion.

[0084] Step 2: Place the precursor dispersion in an oven at 140 °C and dry for 8 h to form a dark brown porous foam; grind the porous foam to form a dark brown powder.

[0085] Step 3: Transfer the dark brown powder to a porcelain boat and heat it in a muffle furnace at 500 °C for 10 hours to obtain an iridium-ruthenium-based porous oxide catalyst, denoted as Sm-IrRuOx with half the amount of urea.

[0086] Test 1: Transmission electron microscopy analysis.

[0087] Figure 1 This is the transmission electron microscopy image of the Sm-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 1. It can be Figure 1 seen that the surface of the Sm-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 1 is rough, has a foam-like porous morphology structure feature, and is composed of particles with a size of 8 nm - 10 nm.

[0088] Test 2: X-ray diffraction analysis.

[0089] Figure 2 This is the X-ray diffraction pattern of the Mn-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 2, as well as IrRuOx, ruthenium oxide, and iridium oxide in Comparative Example 1. Among them, RuOx and IrOx are ruthenium oxide and iridium oxide respectively; IrRuOx is the iridium-ruthenium-based porous oxide catalyst in Comparative Example 1.

[0090] From Figure 2 the results, it can be shown that the Mn-doped iridium-ruthenium-based porous oxide catalyst prepared in Example 2 has an oxide structure.

[0091] Test 3: Oxygen evolution reaction electrocatalytic performance test.

[0092] Test the oxygen evolution reaction electrocatalytic performance of the iridium-ruthenium-based porous oxide catalysts prepared in Examples 1 - 4. The test methods and conditions are as follows:

[0093] All the electrochemical test data were collected by a Shanghai Chenhua workstation. The electrochemical oxygen evolution performance was tested using a three-electrode system. The working electrode was a Pine disk electrode, the reference electrode was a saturated calomel electrode, and the counter electrode was a carbon rod. The electrolyte for the oxygen evolution reaction was 0.1 M perchloric acid solution, and the potential window for the oxygen evolution reaction was 1.3 V vs. RHE to 1.5 V vs. RHE, with a scan rate of 5 mV·s -1 。

[0094] Taking commercial iridium oxide IrO 2 as Control 1 and ruthenium oxide RuO 2 catalyst as Control 2.

[0095] Table 1 Electro-catalytic performance of iridium-ruthenium-based porous oxide catalysts for oxygen evolution reaction

[0096]

[0097]

[0098] Note: The doping amount of low electronegativity elements is the mole percentage of low electronegativity elements in the iridium-ruthenium-based porous oxide catalyst.

[0099] Figure 3 Figure showing the comparison of the oxygen evolution reaction activities of the Mn-IrRuOx catalyst, La-IrRuOx catalyst, and Gd-IrRuOx catalyst prepared in Examples 2 to 4 and the commercial IrO 2 catalyst under acidic conditions.

[0100] From Figure 3 Combined with the results in Table 1, it can be seen that the series of iridium-ruthenium-based porous oxide catalysts doped with low electronegativity elements prepared in Examples 1 to 4 of the present invention all exhibit excellent electro-catalytic performance for the oxygen evolution reaction. Among them, the electro-catalytic performance of Mn-IrRuOx for the oxygen evolution reaction is the best, with an overpotential of 237 mV, which is 118 mV lower than that of the commercial IrO2 catalyst.

[0101] From the results of Examples 1 to 4, it can be seen that in order to ensure the optimal performance of the product catalyst, it is necessary to ensure that the mole percentage of the low electronegativity metal element in the iridium-ruthenium-based porous oxide catalyst is 5% to 10%.

[0102] It can be seen from a comparison between Example 1 and Comparative Examples 1 to 3 that when the molar content of the low electronegativity metal element is too low, less than 5%, the overpotential of the iridium-ruthenium-based porous oxide catalyst will be too high; while when the molar content of the low electronegativity metal element increases to more than 10%, the overpotential of the iridium-ruthenium-based porous oxide catalyst is also too high, and the covalency of the ruthenium-oxygen bond in the iridium-ruthenium-based porous oxide catalyst is too low, which will cause the catalyst to quickly deactivate during operation at high current density and the stability to be significantly reduced. This further proves that when the molar percentage of the low electronegativity metal element in the iridium-ruthenium-based porous oxide catalyst is 5% to 10%, the performance of the product catalyst can reach the optimum.

[0103] It can be seen from a comparison between Example 1 and Comparative Examples 4 and 5 that when glucose is used as a pore-forming agent and the amount of the pore-forming agent is insufficient, the performance of the catalyst will deteriorate; while when urea is used as a surfactant and the amount of the surfactant is insufficient, the prepared iridium-ruthenium-based porous oxide catalyst cannot form a porous foam structure. Therefore, compared with Comparative Examples 4 and 5, Example 1 of the present invention can regulate the porous foam structure of the catalyst and improve the catalyst performance by adding appropriate amounts of glucose and urea.

[0104] In summary, the embodiments of the present invention prepare an iridium-ruthenium-based porous oxide catalyst doped with a low electronegativity element through doping with a low electronegativity element, which can not only greatly improve the stability of the catalyst, but also optimize the electronic structure of the active center, inhibit the excessive oxidation and precipitation of ruthenium, so as to reduce the overpotential of the iridium-ruthenium-based porous oxide catalyst, showing efficient and stable oxygen evolution catalytic performance, and solving the problems that iridium oxide requires a very high overpotential to drive OER and ruthenium is extremely easy to be oxidized and dissolved, and it is difficult to maintain high activity under high potential operation, thus affecting the long-term stability of the catalyst. Moreover, the overpotential of the iridium-ruthenium-based porous oxide catalyst doped with a low electronegativity element prepared in Example 1 of the present invention is 237 mV, which is 118 mV lower than that of the commercial IrO 2 catalyst, showing efficient and stable oxygen evolution catalytic performance.

[0105] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an iridium-ruthenium-based porous oxide catalyst, characterized in that: The following steps are involved: The iridium source, the ruthenium source, the low electronegativity metal precursor salt, the pore former, the surfactant and the solvent are mixed uniformly to obtain a precursor solution; The precursor solution is heat-treated to remove the solvent, and ground to obtain a precursor powder; the precursor powder is calcined in an air atmosphere to obtain an iridium-ruthenium-based porous oxide catalyst doped with a low electronegativity metal; The low electronegativity metal precursor salt is at least one of a chromium source, a manganese source, a yttrium source, a lanthanum source, a praseodymium source, a neodymium source, a samarium source, a gadolinium source and an erbium source; The pore-forming agent is at least one of glucose and fructose; The surfactant is at least one of urea, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride.

2. The method for preparing the iridium-ruthenium-based porous oxide catalyst according to claim 1, characterized in that: In the precursor solution, the concentration of the iridium source is 2 mg / mL to 9 mg / mL; the concentration of the ruthenium source is 1.5 mg / mL to 6 mg / mL; the concentration of the low electronegativity metal precursor salt is 0.5 mg / mL to 1.5 mg / mL; the concentration of the pore former is 1 mg / mL to 2 g / mL; and the concentration of the surfactant is 100 mg / mL to 400 mg / mL.

3. The method for preparing the iridium-ruthenium-based porous oxide catalyst according to claim 1, characterized in that: The iridium source is iridium trichloride, iridium carbonyl or iridium acetylacetonate; the ruthenium source is ruthenium trichloride, triruthenium dodecacarbonyl or ruthenium acetylacetonate; the chromium source is chromium trichloride or chromium acetylacetonate; the manganese source is manganese chloride or manganese acetylacetonate; the yttrium source is yttrium chloride or yttrium nitrate; the lanthanum source is lanthanum chloride or lanthanum acetylacetonate; the praseodymium source is praseodymium chloride or praseodymium nitrate; the neodymium source is neodymium chloride or neodymium acetylacetonate; the promethium source is promethium chloride; the samarium source is samarium chloride; the gadolinium source is gadolinium chloride or gadolinium nitrate; and the erbium source is erbium chloride or holmium nitrate.

4. The method for preparing the iridium-ruthenium-based porous oxide catalyst according to claim 1, characterized in that: The solvent is at least one of water, ethanol, benzyl alcohol and N,N-dimethylformamide.

5. The method for preparing the iridium-ruthenium-based porous oxide catalyst according to claim 1, characterized in that: The calcination temperature is 400° C. to 1000° C., and the calcination time is 6 hours to 12 hours.

6. The method for preparing the iridium-ruthenium-based porous oxide catalyst according to claim 1, characterized in that: The temperature of the heat treatment is 100°C to 200°C.

7. An iridium-ruthenium-based porous oxide catalyst, characterized in that: The catalyst is prepared by the method for preparing the iridium-ruthenium-based porous oxide catalyst described in any one of claims 1 to 6.

8. The iridium-ruthenium-based porous oxide catalyst according to claim 7, characterized in that: The particle size of the iridium-ruthenium-based porous oxide catalyst is 8nm-10nm.

9. The iridium-ruthenium-based porous oxide catalyst according to claim 7, characterized in that: The iridium-ruthenium-based porous oxide catalyst is obtained by doping low-electronegativity metal elements into iridium-ruthenium-based oxides; the molar percentage of the low-electronegativity metal elements in the iridium-ruthenium-based porous oxide catalyst is less than 10%.

10. An application of an iridium-ruthenium-based porous oxide catalyst as an electrolytic water oxygen evolution catalyst, characterized in that: The iridium ruthenium based porous oxide catalyst is the iridium ruthenium based porous oxide catalyst according to claim 7.

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