High-entropy oxide anode with rutile structure and preparation method and application thereof

Abstract

The invention discloses a high-entropy oxide anode with a rutile structure and a preparation method and application of the high-entropy oxide anode, and relates to the field of high-entropy materials. The chemical composition formula of the high-entropy oxide anode with the rutile structure is [MN] Ox, M is any one or two of Ru and Ir, and N is any three or four of Ta, Sn, Sb, Re, Mn, Nb and Hf; the molar ratio of each metal element to all metal elements is 20%-25%, and the molar ratio of any two metal elements is (1: 1.2)-(1.2: 1). The preparation method has the beneficial effects that the electronic structure of an Ir / Ru site can be changed through the synergistic effect of various metal elements, so that the Ir / Ru site has excellent electrocatalytic activity, the peroxidation phenomenon of the Ir / Ru site in the acidic oxygen evolution reaction (OER) process is inhibited, and a high-stability anode capable of being used in an acidic medium is expected to be obtained. The preparation method of the rutile type high-entropy oxide anode is simple, low in cost and good in effect, the anode elements are evenly distributed, the crystal structure is single, and the rutile type high-entropy oxide anode shows excellent performance in the water electrolysis oxygen evolution reaction in the acid environment.

Description

Technical Field

[0001] The present invention belongs to the field of high-entropy materials, and particularly relates to a rutile-structured high-entropy oxide anode and its preparation method and application. Background Art

[0002] Currently, anode materials for the oxygen evolution reaction (OER) in acidic media have been widely used in various fields, including proton exchange membrane water electrolyzers (PEMWE), organic synthesis processes, hydrometallurgy, and sewage treatment. During the electrochemical water splitting process, the anode OER faces thermodynamic challenges and slow kinetics, requiring a relatively high overpotential to sustain the reaction. Currently, only iridium-based oxides, ruthenium-based oxides, and their derivatives have sufficient corrosion resistance to withstand the harsh acidic corrosion and oxidation environment of OER. Among them, the scarcity of iridium-based electrocatalysts makes it difficult to meet the large-scale industrial demand. During the OER process, the over-oxidation of Ru species easily produces soluble Ru n>+4 species, which will accelerate degradation and result in poor stability. Therefore, there is an urgent need to develop a new type of OER electrocatalyst with excellent electrocatalytic activity, high long-term stability, environmental friendliness, and low cost in acidic media.

[0003] To address the above problems, the literature "Insulating High-Entropy Ruthenium Oxide as a Highly Efficient Oxygen-Evolving Electrocatalyst in Acid, ACS Catalysis, 2023, 13(6): 3983-3989" discloses a (Ru 0.2 Ir 0.2 Cr 0.2 W 0.2 Cu 0.2 )O2 anode with a high-entropy ruthenium structure. Although its electrocatalytic performance and acid corrosion resistance have been improved, the content of Ir and Ru elements in the anode obtained by the method in this literature is relatively high, resulting in a high economic cost for preparing the anode.

[0004] Chinese Patent CN116354420A discloses a rutile-type high-entropy oxyfluoride material and its preparation method and application. The preparation drugs of this patent mainly include any one or more of RuO2, MnO2, and TiO2, as well as four fluorides MgF2, ZnF2, CoF2, and MnF2. Although this patent can prepare an anode with a ruthenium structure, the four fluorides MgF2, ZnF2, CoF2, and MnF2 are toxic and pose serious hazards to the health of operators and the environment. Summary of the Invention

[0005] The object of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a rutile-structured high-entropy oxide anode, a preparation method and an application thereof. The rutile-structured high-entropy oxide anode prepared by the preparation method provided by the present invention exhibits excellent oxygen evolution performance in an acidic environment and outstanding acid corrosion resistance.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, the present invention provides a rutile-structured high-entropy oxide anode, which is characterized in that the chemical composition formula of the rutile-structured high-entropy oxide anode is [MN]O x . Wherein M is any one or two of Ru and Ir, and N is any three or four of Ta, Sn, Sb, Re, Mn, Nb, and Hf; the molar ratio of each metal element to all metal elements is 20% - 25%, and the molar ratio of any two metal elements is 1:1.2 - 1.2:1.

[0008] On the other hand, the present invention provides a preparation method of a rutile-structured high-entropy oxide anode, which is characterized by comprising the following steps:

[0009] S1. Add iridium chloride and ruthenium chloride into an equal proportion of ethanol and isopropanol mixed solution respectively, stir and dissolve to obtain an iridium chloride mixed solution and a ruthenium chloride mixed solution with equal molar ratios respectively;

[0010] S2. Add four kinds of drugs of tantalum chloride, stannous chloride pentahydrate, antimony trichloride, manganese chloride, niobium pentachloride, ammonium perrhenate, hafnium chloride and erbium acetate with approximate equal molar ratios into the obtained iridium chloride mixed solution and ruthenium chloride mixed solution with equal molar ratios respectively, stir evenly to obtain a precursor solution for preparing a high-entropy oxide anode;

[0011] S3. Stir the obtained precursor solution of the high-entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300W and an ultrasonic frequency of 40KHz to perform ultrasonic oscillation on the precursor solution for 20 - 30 minutes to obtain a uniform precursor solution for preparing a high-entropy oxide anode.

[0012] A specific embodiment of the present invention further includes pre-treating the substrate before the brush coating solution treatment, and the pre-treatment includes degreasing treatment and etching treatment of the substrate in sequence;

[0013] The degreasing treatment includes: putting the substrate into a beaker filled with acetone, then placing it in an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz for ultrasonic cleaning to remove the oil stains on the surface. The ultrasonic time is 20 - 30 min. After taking it out of the acetone, it is rinsed 3 - 5 times with deionized water. Then the rinsed substrate is put into a beaker filled with an alkaline solution, and then placed in a water bath with a heating rate of 5 °C / min. The temperature of the water bath is 70 - 90 °C, and the heat preservation time for the alkaline solution etching treatment is 50 - 70 min. After taking it out of the alkaline solution, it is rinsed 3 - 5 times with deionized water to obtain a clean and oil-free substrate;

[0014] The alkaline solution includes the following components: 50 - 70 g / L of sodium hydroxide, 20 - 40 g / L of sodium carbonate, 30 - 40 g / L of sodium phosphate, 5 - 15 g / L of sodium sulfite, and deionized water is added to 1 L.

[0015] In a specific embodiment of the present invention, the etching treatment includes: putting the degreased substrate into a beaker filled with an acid solution, and placing it in a water bath with a heating rate of 5 °C / min. The temperature of the water bath is 95 - 105 °C, and the heat preservation time for the acid solution etching treatment is 25 - 35 min. After taking it out of the acid solution, it is rinsed 3 - 5 times with deionized water;

[0016] The acid solution includes the following components: 80 - 100 g / L of sulfuric acid, and deionized water is added to 1 L.

[0017] The present invention has at least one of the following beneficial effects:

[0018] 1. The precursor solution of the present invention includes components such as chloroiridic acid, tantalum pentachloride, stannic chloride pentahydrate, ammonium perrhenate, manganese chloride, etc. By designing a high-entropy solid solution of five or more metal elements and utilizing the ternary synergistic effect of "noble metal-transition metal-rare earth element", the loading amount of noble metals is greatly reduced. In addition, during the acidic OER process, IrO2 / RuO2 generally serves as the acidic OER catalytic active center. Elements such as Ta, Re, and Nb have excellent acid corrosion resistance, and elements such as Sn, Re, Hf, and Mn dynamically adjust the electronic structure of IrO2 / RuO2, maximizing the OER catalytic efficiency. This strategy breaks the limitation of traditional high-entropy oxides that only rely on transition metal elements and provides a new paradigm for the development of low-cost, high-activity, and long-life industrial anodes.

[0019] 2. The present invention uses a thermal decomposition technique to prepare a high-entropy oxide anode. The thermal decomposition technique directly forms a single rutile structure through the breaking and reconstruction of chemical bonds within the precursor molecules, eliminating the subsequent high-temperature calcination (>800 °C) in the hydrothermal method and the long-time ball milling (>12 h) required in the solid-phase method. Therefore, it has excellent structural stability. In addition, the thermal decomposition method can be combined with industrial preparation, saving preparation time and energy consumption costs, and avoiding the strict requirements for pH value, chelating agent ratio, and aging time in the sol-gel method. Finally, the high-entropy oxide anode prepared by the thermal decomposition technique has a relatively large active specific surface area, which can provide more active sites and further improve its electrocatalytic activity.

[0020] 3. In the present invention, the mixed solution is used as the precursor solution, which is brush-coated on the surface of the substrate. Then, it is placed in a muffle furnace for drying and thermal decomposition respectively. The obtained anode has extremely few cracks on the surface and has a nanoflower structure. The extremely few cracks can prevent active oxygen from entering the interface between the substrate and the catalytic coating. The existence of the nanoflower structure is beneficial to increasing the specific surface area of the anode, thereby exposing more active sites and further improving the electrocatalytic performance and durability of the anode.

[0021] 4. The present invention first pre-treats the substrate, and the pre-treatment includes degreasing treatment and etching treatment carried out in sequence; the degreasing treatment can remove the oil and impurities on the surface of the substrate, and the etching treatment can completely remove the oxide film on the surface of the substrate; then, solution brush-coating treatment is carried out to enable the precursor solution to be evenly distributed on the surface of the treated substrate; finally, thermal decomposition treatment is carried out. After the above treatments, the high-entropy oxide anode obtained by the present invention has excellent electrocatalytic activity and high OER catalytic efficiency; it has excellent acid corrosion resistance and has a complete rutile structure; it has a low contact resistance and good electrical conductivity. Description of the Drawings

[0022] Figure 1 XRD pattern of the high-entropy oxide anode obtained in Example 2;

[0023] Figure 2 LSV graph of the high-entropy oxide anode obtained in Example 2. Detailed Description of the Invention

[0024] The following uses specific examples to further elaborate on the present invention in detail, but the present invention is not limited to the following specific examples.

[0025] The first aspect of the present invention provides a high-entropy oxide electrode with a rutile structure, including the following components:

[0026] Iridium chloride acid 5 - 20 g / L, stannic chloride pentahydrate 10 - 50 g / L, antimony trichloride 10 - 40 g / L, ammonium perrhenate 10 - 40 g / L, manganese chloride 1 - 20 g / L, ruthenium chloride 0.2 - 8 g / L, niobium pentachloride 10 - 40 g / L, hafnium chloride 20 - 40 g / L, tantalum chloride 20 - 50 g / L, ethanol and isopropanol are added in equal proportion to 1 L.

[0027] In the present invention, the precursor solution preferably includes iridium chloride acid 5 - 20 g / L, more preferably 6 - 15 g / L, and still more preferably 8 - 12 g / L.

[0028] In the present invention, the precursor solution preferably includes stannic chloride pentahydrate 10 - 50 g / L, more preferably 15 - 30 g / L, and still more preferably 18 - 28 g / L.

[0029] In the present invention, the precursor solution preferably includes antimony trichloride 10 - 40 g / L, more preferably 15 - 35 g / L, and still more preferably 20 - 30 g / L.

[0030] In the present invention, the precursor solution preferably includes ammonium perrhenate 10 - 40 g / L, more preferably 15 - 35 g / L, and still more preferably 18 - 28 g / L.

[0031] In the present invention, the precursor solution preferably includes manganese chloride 1 - 20 g / L, more preferably 5 - 15 g / L, and still more preferably 8 - 13 g / L.

[0032] In the present invention, the precursor solution preferably includes ruthenium chloride 0.2 - 8 g / L, more preferably 1 - 6 g / L, and still more preferably 2 - 5 g / L.

[0033] In the present invention, the precursor solution preferably includes niobium pentachloride 10 - 40 g / L, more preferably 15 - 35 g / L, and still more preferably 20 - 30 g / L.

[0034] In the present invention, the precursor solution preferably includes hafnium chloride 20 - 40 g / L, more preferably 25 - 35 g / L, and still more preferably 28 - 32 g / L.

[0035] In the present invention, the precursor solution preferably includes tantalum chloride 20 - 50 g / L, more preferably 25 - 45 g / L, and still more preferably 30 - 40 g / L.

[0036] The second aspect of the present invention provides a preparation method of the above precursor solution, comprising the following steps:

[0037] S1. Add iridium chloride and ruthenium chloride into an equal - proportion mixed solution of ethanol and isopropanol respectively, stir to dissolve, and prepare an iridium chloride mixed solution and a ruthenium chloride mixed solution with an equimolar ratio respectively;

[0038] S2. Add four kinds of drugs from stannic chloride pentahydrate, antimony trichloride, manganese chloride, niobium pentachloride, ammonium perrhenate, hafnium chloride and tantalum chloride with an approximate equimolar ratio into the prepared iridium chloride mixed solution and ruthenium chloride mixed solution with an equimolar ratio respectively, stir evenly to obtain a precursor solution for preparing a high - entropy oxide anode;

[0039] S3. Stir the obtained precursor solution of the high - entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300W and an ultrasonic frequency of 40KHz to perform ultrasonic oscillation on the precursor solution for 20 - 30min to obtain a precursor solution for preparing a high - entropy oxide anode with uniform composition.

[0040] In order to obtain a high - entropy oxide electrode with uniform composition, the present invention adopts a physical method and uses ultrasonic oscillation on it. Under the combined action of these two methods, a precursor solution with uniform composition is prepared.

[0041] The third aspect of the present invention provides a method for preparing a high - entropy oxide anode, including the following steps:

[0042] Step 1. Pretreat the substrate; the pretreatment preferably includes degreasing and etching treatments carried out in sequence;

[0043] (1) Degreasing treatment: The degreasing treatment includes: putting the titanium substrate into a beaker filled with acetone, and then putting it into an ultrasonic cleaner with an ultrasonic power of 300W and an ultrasonic frequency of 40KHz for ultrasonic cleaning to remove the oil stains on the surface. The ultrasonic time is 20 - 30min. After taking it out of the acetone, rinse it with deionized water 3 - 5 times. Then put the rinsed substrate into a beaker filled with an alkaline cleaning solution, and then put it into a water - bath pot with a heating rate of 5℃ / min. The temperature of the water - bath pot is 70 - 90℃, and the heat - preservation time for the alkaline cleaning solution etching treatment is 50 - 70min. After taking it out of the alkaline cleaning solution, rinse it with deionized water 3 - 5 times to obtain a clean and oil - free titanium substrate;

[0044] The alkaline cleaning solution includes the following components: 50 - 70g / L of sodium hydroxide, 20 - 40g / L of sodium carbonate, 30 - 40g / L of sodium phosphate, 5 - 15g / L of sodium sulfite, and deionized water is added to 1L;

[0045] In the present invention, the pickling solution preferably comprises 50 - 70 g / L of sodium hydroxide, more preferably 52 - 62 g / L, and even more preferably 55 - 60 g / L. In the present invention, the pickling solution preferably comprises 20 - 40 g / L of sodium carbonate, more preferably 24 - 28 g / L, and even more preferably 25 - 27 g / L. In the present invention, the pickling solution preferably comprises 30 - 40 g / L of sodium phosphate, more preferably 32 - 38 g / L, and even more preferably 34 - 37 g / L. In the present invention, the pickling solution preferably comprises 5 - 15 g / L of sodium sulfite, more preferably 6 - 10 g / L, and even more preferably 5 - 8 g / L.

[0046] In the present invention, the temperature of the degreasing treatment is preferably 70 - 90 °C, more preferably 75 - 85 °C, and even more preferably 77 - 82 °C. In the present invention, the time of ultrasonic treatment with acetone in the degreasing treatment is preferably 20 - 30 min, more preferably 22 - 28 min, and even more preferably 23 - 26 min. The time of pickling solution treatment in the degreasing treatment is preferably 50 - 70 min, more preferably 55 - 65 min, and even more preferably 58 - 63 min.

[0047] In the present invention, the degreasing treatment can remove oil stains and impurities on the surface of the titanium substrate.

[0048] After the degreasing treatment is completed, the present invention further preferably includes rinsing the obtained titanium substrate; the rinsing agent used for rinsing is preferably deionized water. The present invention has no special limitation on the rinsing process, and those well-known to those skilled in the art can be used.

[0049] (2) Etching treatment: Put the degreased titanium substrate into a beaker filled with acid solution, and place it in a water bath with a heating rate of 5 °C / min to perform etching treatment on the substrate.

[0050] In the present invention, the sulfuric acid for the etching treatment is preferably 80 - 100 g / L, more preferably 85 - 95 g / L, and even more preferably 86 - 92 g / L; the temperature of the water bath is preferably 95 - 105 °C, more preferably 96 - 104 °C, and even more preferably 99 - 102 °C. In the present invention, the time of the etching treatment is preferably 25 - 35 min, more preferably 27 - 33 min, and even more preferably 28 - 32 min.

[0051] In the present invention, the etching treatment can remove the oxide film on the surface of the substrate.

[0052] After the etching treatment is completed, the present invention further preferably includes rinsing the obtained substrate; the rinsing agent used for rinsing is preferably deionized water. The present invention has no special limitation on the rinsing process, and those well-known to those skilled in the art can be used.

[0053] Step 3: Perform thermal decomposition treatment on the substrate with the precursor solution after brushing; the specific method includes: after uniformly brushing the precursor solution of the rutile-structured high-entropy oxide anode on the surface of the corrosion-resistant titanium substrate using a brush, put it into a muffle furnace for drying and sintering, and finally obtain a rutile-structured high-entropy oxide anode with uniform composition;

[0054] In the present invention, the number of brush coats is preferably 1 to 10 layers, more preferably 3 to 8 layers, and even more preferably 4 to 7 layers.

[0055] In the present invention, the drying temperature of each layer during heat treatment is preferably 90°C to 120°C, more preferably 95°C to 115°C, and even more preferably 98°C to 110°C; the drying time of each layer is preferably 5 to 20 min, more preferably 8 to 18 min, and even more preferably 9 to 15 min; the sintering temperature of each layer is preferably 400°C to 480°C, more preferably 410°C to 470°C, and even more preferably 425 to 455°C; the sintering time of each layer is preferably 5 to 20 min, more preferably 7 to 18 min, and even more preferably 8 to 15 min, and the sintering time of the last layer is preferably 25 to 50 min, more preferably 27 to 48 min, and even more preferably 29 to 40 min.

[0056] The third aspect of the present invention provides a high-entropy oxide anode prepared by the above method. There are very few cracks and some fine pores on the surface of the high-entropy oxide anode. The very few cracks can prevent active oxygen from entering the interface between the substrate and the catalytic coating, and the existence of some fine pores is beneficial to increasing the specific surface area of the anode, which is beneficial to improving the electrocatalytic activity and acid corrosion resistance of the high-entropy oxide anode.

[0057] The high-entropy oxide anode obtained in the present invention has excellent electrocatalytic performance and stability in acidic media.

[0058] The fourth aspect of the present invention provides the application of the above high-entropy oxide anode in the electrolysis industry. The surface of the above high-entropy oxide anode has fewer cracks, has good electrical conductivity and electrocatalytic performance, and can be used as an anode material in the electrolysis industry.

[0059] The present invention does not have any special limitations on the specific implementation manners of the application, and those well-known to those skilled in the art can be adopted.

[0060] Example 1

[0061] Composition of the pickling solution: 56 g / L of sodium hydroxide, 25 g / L of sodium carbonate, 34 g / L of sodium phosphate, 5 g / L of sodium sulfite, and deionized water is added to 1 L;

[0062] Composition of pickling solution: 87 g / L of sulfuric acid, deionized water added to 1 L;

[0063] Composition of precursor solution: 9 g / L of iridium chloride hydrate, 20 g / L of stannous chloride pentahydrate, 22 g / L of antimony trichloride, 29 g / L of hafnium chloride, 9 g / L of manganese chloride, 1 L of an equimolar mixture of ethanol and isopropanol;

[0064] The preparation method of the precursor solution includes:

[0065] S1. Add iridium chloride hydrate to an equimolar mixture of ethanol and isopropanol, stir and dissolve to obtain an iridium chloride hydrate mixed solution with an equimolar ratio respectively;

[0066] S2. Add approximately equimolar amounts of stannous chloride pentahydrate, antimony trichloride, hafnium chloride, and manganese chloride to the obtained iridium chloride hydrate mixed solution and ruthenium chloride mixed solution with an equimolar ratio respectively, stir evenly to obtain a precursor solution for preparing a high-entropy oxide anode;

[0067] S3. Stir the obtained precursor solution for the high-entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz to perform ultrasonic oscillation on the precursor solution for 25 min to obtain a precursor solution for preparing a high-entropy oxide anode with uniform composition.

[0068] The pretreatment method of the substrate includes:

[0069] Put the titanium substrate into a beaker containing acetone solution, and then put it into an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz for ultrasonic cleaning to remove the oil on the surface. The ultrasonic time is 22 min. After taking it out of the acetone, rinse it 3 times with deionized water. Then put the rinsed substrate into a beaker containing pickling solution, and then put it into a water bath with a heating rate of 5 °C / min. The temperature of the water bath is 78 °C, and the holding time for pickling treatment with the pickling solution is 59 min. After taking it out of the pickling solution, rinse it 3 times with deionized water to obtain a clean and oil-free titanium substrate;

[0070] Put the degreased titanium substrate into a beaker containing acid solution, and put it into a water bath with a heating rate of 5 °C / min to etch the substrate; the temperature of the water bath is 98 °C, and the etching treatment is carried out for 29 min. After the etching treatment is completed, the present invention preferably further includes rinsing the obtained titanium substrate; the rinsing agent used for rinsing is preferably deionized water;

[0071] The heat treatment process includes:

[0072] After uniformly brushing the precursor solution of the rutile-structured high-entropy oxide anode on the surface of the corrosion-resistant titanium substrate with a brush, the number of brush coats is 4 layers. Then, it is placed in a muffle furnace for drying and sintering. The drying temperature for each layer is 99 °C, the drying time for each layer is 13 min, the sintering temperature for each layer is 428 °C, the sintering time for each layer is 28 min, and the sintering time for the last layer is 36 min. Finally, a rutile-structured high-entropy oxide anode with uniform composition is obtained.

[0073] Example 2

[0074] Composition of the pickling solution: 58 g / L of sodium hydroxide, 26 g / L of sodium carbonate, 35 g / L of sodium phosphate, 7 g / L of sodium sulfite, and deionized water is added to 1 L;

[0075] Composition of the acid cleaning solution: 89 g / L of sulfuric acid, and deionized water is added to 1 L;

[0076] Composition of the precursor solution: 10 g / L of iridium chloride acid, 27 g / L of tin tetrachloride pentahydrate, 23 g / L of antimony trichloride, 27 g / L of ammonium perrhenate, 12 g / L of manganese chloride, and 1 L of an equimolar mixture of ethanol and isopropanol;

[0077] The preparation method of the precursor solution includes:

[0078] S1. Add iridium chloride acid to an equimolar mixture of ethanol and isopropanol, stir and dissolve to obtain an iridium chloride acid mixed solution with an equimolar ratio respectively;

[0079] S2. Add approximately equimolar amounts of tin tetrachloride pentahydrate, antimony trichloride, ammonium perrhenate, and manganese chloride to the obtained iridium chloride acid mixed solution and ruthenium chloride mixed solution with an equimolar ratio respectively, and stir evenly to obtain the precursor solution for preparing the high-entropy oxide anode;

[0080] S3. Stir the obtained precursor solution of the high-entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz to perform ultrasonic oscillation on the precursor solution for 22 min to obtain a precursor solution for preparing the high-entropy oxide anode with uniform composition;

[0081] The pretreatment method of the substrate includes:

[0082] Put the titanium substrate into a beaker containing acetone solution, and then put it into an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz for ultrasonic cleaning to remove the oil on the surface. The ultrasonic time is 26 min. After taking it out of the acetone, rinse it 5 times with deionized water. Then put the rinsed substrate into a beaker containing alkaline cleaning solution, and then put it into a water bath at a heating rate of 5 °C / min. The temperature of the water bath is 80 °C, and the holding time for alkaline cleaning solution etching treatment is 60 min. After taking it out of the alkaline cleaning solution, rinse it 5 times with deionized water to obtain a clean and oil-free titanium substrate;

[0083] Put the degreased titanium substrate into a beaker containing acid solution, and put it into a water bath at a heating rate of 5 °C / min for etching treatment of the substrate; the temperature of the water bath is 100 °C, and the etching treatment is carried out for 30 min. After the etching treatment is completed, the present invention preferably further includes rinsing the obtained titanium substrate; the rinsing agent used for rinsing is preferably deionized water;

[0084] The heat treatment process includes:

[0085] After evenly brushing the precursor solution of the rutile-structured high-entropy oxide anode on the surface of the corrosion-resistant titanium substrate with a brush, the number of brush coats is 5 layers. Then put it into a muffle furnace for drying and sintering. The drying temperature for each layer is 100 °C, the drying time for each layer is 10 min, the sintering temperature for each layer is 450 °C, the sintering time for each layer is 30 min, and the sintering time for the last layer is 30 min. Finally, a rutile-structured high-entropy oxide anode with uniform composition is obtained.

[0086] Example 3

[0087] Composition of the alkaline cleaning solution: sodium hydroxide 57 g / L, sodium carbonate 27 g / L, sodium phosphate 36 g / L, sodium sulfite 6 g / L, and deionized water is added to 1 L;

[0088] Composition of the acid cleaning solution: sulfuric acid 90 g / L, and deionized water is added to 1 L;

[0089] Composition of the precursor solution: iridium chloride 9 g / L, tin tetrachloride pentahydrate 24 g / L, antimony trichloride 23 g / L, ammonium perrhenate 20 g / L, niobium pentachloride 25 g / L, and 1 L of an equal proportion mixture of ethanol and isopropanol;

[0090] The preparation method of the precursor solution includes:

[0091] S1. Add iridium chloride to an equal proportion mixture solution of ethanol and isopropanol, stir and dissolve to prepare an iridium chloride mixed solution with an equal molar ratio;

[0092] S2. Add stannic chloride pentahydrate, antimony trichloride, ammonium perrhenate, and niobium pentachloride with approximate equimolar ratios to the prepared equimolar ratio mixed solutions of iridium chlorate and ruthenium chloride respectively, stir evenly to obtain a precursor solution for preparing a high-entropy oxide anode;

[0093] S3. Stir the obtained precursor solution of the high-entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz to perform ultrasonic oscillation on the precursor solution for 26 min to obtain a precursor solution of the high-entropy oxide anode with uniform composition;

[0094] The pretreatment method of the substrate includes:

[0095] Put the titanium substrate into a beaker containing acetone solution, and then put it into an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz for ultrasonic cleaning to remove the oil on the surface. The ultrasonic time is 28 min. After taking it out of the acetone, rinse it 5 times with deionized water. Then put the rinsed substrate into a beaker containing alkaline cleaning solution, and then put it into a water bath with a heating rate of 5 °C / min. The temperature of the water bath is 81 °C, and the holding time for alkaline cleaning solution etching treatment is 62 min. After taking it out of the alkaline cleaning solution, rinse it 4 times with deionized water to obtain a clean and oil-free titanium substrate;

[0096] Put the degreased titanium substrate into a beaker containing acid solution, and put it into a water bath with a heating rate of 5 °C / min for etching treatment of the substrate; the temperature of the water bath is 101 °C, and the etching treatment is 32 min. After the etching treatment is completed, the present invention preferably further includes rinsing the obtained titanium substrate; the rinsing agent used for rinsing is preferably deionized water;

[0097] The heat treatment process includes:

[0098] After evenly brushing the precursor solution of the rutile-structured high-entropy oxide anode on the surface of the corrosion-resistant titanium substrate with a brush, the number of brush coats is 6 layers. Then put it into a muffle furnace for drying and sintering. The drying temperature for each layer is 105 °C, the drying time for each layer is 13 min, the sintering temperature for each layer is 454 °C, the sintering time for each layer is 12 min, and the sintering time for the last layer is 35 min. Finally, a rutile-structured high-entropy oxide anode with uniform composition is obtained.

[0099] Comparative Example 1

[0100] Prepare an oxide electrode according to the method of Example 2. The difference from Example 3 is that the precursor solution does not include iridium chlorate.

[0101] Performance Test

[0102] Test Example 1

[0103] The XRD test was carried out on the high-entropy oxide obtained in Example 2, and the test results are as Figure 1 shown. It can be seen from Figure 2 that obvious diffraction peaks appear at 2θ = 28.02°, 34.70°, 40.06°, 45.02° and 69.33° for the composite coating, which coincide with the PDF (PDF = 43-1019) card of IrO2. Obvious diffraction peaks appearing at 2θ = 35.08°, 38.40°, 40.16°, 62.94°, 70.63°, 74.14°, 76.19° and 77.34° are in good agreement with the PDF (PDF = 44-1294) of titanium. This is mainly because an ultrathin film is formed on the titanium substrate at the anode, and the X-ray directly contacts with metallic titanium; according to the XRD diffraction peaks, the product prepared in Example 2 is mainly composed of IrO2 with a rutile structure.

[0104] Test Example 2

[0105] The electrochemical performance tests were carried out on the high-entropy oxide anodes obtained in Examples 1-3 and Comparative Example 1, including linear sweep voltammetry, AC impedance test, cyclic voltammetry test and stability test. All the electrochemical performance test methods were carried out in 0.5M H2SO4 solution.

[0106] The test results are shown in Table 1.

[0107] Table 1 Electrochemical performance test results of the high-entropy oxide anodes obtained in Examples 1-3 and Comparative Example 1

[0108]

[0109] According to the test results in Table 1, the overpotential of the high-entropy oxide anodes prepared in Examples 1-3 is 160-245 mV at 10 mA cm -2 , the Tafel slope is 23.53-53.15 mV dec -1 , the charge transfer resistance is 0.05-1.78 Ω cm -2 , the double-layer capacitance is 133.90-309.86 mF cm -2 , and stable oxygen evolution is tested for 100-500 h at a current density of 200 mA cm -2 . It can be seen that the high-entropy oxide obtained in the present invention has a small Tafel slope and an extremely low charge transfer resistance, with fast reaction kinetics and good electrical conductivity; the double-layer capacitance is the highest, indicating that it has the highest active specific surface area, and further indicating that it has excellent electrocatalytic activity; the anode can stably evolve oxygen for 500 hours in an acidic environment, indicating its excellent acid corrosion resistance.

[0110] Comparing Examples 1 to 3 with Comparative Example 1, it can be seen that the overpotential, Tafel slope, and charge transfer resistance of the high-entropy oxide anodes prepared in Examples 1 to 3 are all smaller than those in Comparative Example 1 (chloroiridic acid was not added to the precursor solution). This shows that under the synergistic action of multiple elements of Ir, Sn, Sb, Re, and Mn, the present invention achieves a smaller Tafel slope and an extremely low charge transfer resistance for the high-entropy oxide anode, with fast reaction kinetics and good electrical conductivity; the double-layer capacitance is the highest, indicating that it has the highest active specific surface area, and further indicating its excellent electrocatalytic activity; the anode can stably evolve oxygen for 500 hours in an acidic environment, indicating its excellent acid corrosion resistance.

[0111] The above are only characteristic implementation examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent exchange or equivalent substitution fall within the scope of the protection of the rights of the present invention.

Claims

1. A rutile-structured high-entropy oxide anode, characterized in that, The chemical composition formula of the rutile-structured high-entropy oxide anode is [MN]O x . Wherein M is any one or both of Ru and Ir, and N is any three or four of Ta, Sn, Sb, Re, Mn, Nb, and Hf; the molar ratio of each metal element to all metal elements is 15% to 25%, and the molar ratio of any two metal elements is 1:1.5 to 1.5:

1.

2. The preparation method of a rutile-structured high-entropy oxide anode according to claim 1, characterized in that, It includes the following steps: S1. Add iridium chloride and ruthenium chloride into an ethanol and isopropanol mixed solution in equal proportions respectively, stir and dissolve them to obtain an iridium chloride mixed solution and a ruthenium chloride mixed solution with an equimolar ratio respectively; S2. Add four kinds of medicines among stannic chloride pentahydrate, antimony trichloride, manganese chloride, niobium pentachloride, ammonium perrhenate, hafnium chloride and tantalum chloride with an approximate equimolar ratio into the above-prepared iridium chloride mixed solution and ruthenium chloride mixed solution with an equimolar ratio respectively, stir evenly to obtain a precursor solution for preparing a high-entropy oxide anode; S3. Stir the obtained precursor solution for the high-entropy oxide anode with a glass rod, and use an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz to perform ultrasonic oscillation on the precursor solution for 20 - 30 min to obtain a uniform precursor solution for preparing a high-entropy oxide anode.

3. A preparation method of a rutile-structured high-entropy oxide anode, characterized in that, It is formed by uniformly brushing the precursor solution of a rutile-structured high-entropy oxide anode according to any one of claims 1 - 2 on the surface of a corrosion-resistant titanium substrate and then performing thermal decomposition.

4. The preparation method of a rutile-structured high-entropy oxide anode according to claim 3, characterized in that, The precursor solution of a rutile-structured high-entropy oxide anode according to any one of claims 1 - 2 is uniformly brushed on the surface of a corrosion-resistant titanium substrate with a brush, the number of brush coats is 1 - 10 layers, the drying temperature for each layer is 90°C - 120°C, the drying time for each layer is 5 - 20 min; the sintering temperature for each layer is 400°C - 480°C, the sintering time for each layer is 5 - 20 min, and the sintering time for the last layer is 25 - 50 min.

5. The preparation method of a rutile-structured high-entropy oxide anode according to claim 3, characterized in that, It also includes pre-treating the substrate before brushing the solution, and the pre-treatment includes degreasing treatment and etching treatment of the substrate in sequence; The degreasing treatment includes: putting the substrate into a beaker filled with acetone, then putting it into an ultrasonic cleaner with an ultrasonic power of 300 W and an ultrasonic frequency of 40 KHz for ultrasonic cleaning to remove the oil stains on the surface, the ultrasonic time is 20 - 30 min, taking it out of the acetone, rinsing it with deionized water 3 - 5 times, then putting the rinsed substrate into a beaker filled with alkali solution, then putting it into a water bath kettle with a heating rate of 5°C / min, the temperature of the water bath kettle is 70 - 90°C, the heat preservation time for alkali solution etching treatment is 50 - 70 min, taking it out of the alkali solution, and rinsing it with deionized water 3 - 5 times to obtain a clean substrate without oil stains; The alkali solution includes the following components: 50 - 70 g / L of sodium hydroxide, 20 - 40 g / L of sodium carbonate, 30 - 40 g / L of sodium phosphate, 5 - 15 g / L of sodium sulfite, and deionized water is added to 1 L.

6. The preparation method of a rutile-structured high-entropy oxide anode according to claim 3, characterized in that, The etching treatment includes: putting the degreased substrate into a beaker filled with acid solution, and putting it into a water bath kettle with a heating rate of 5°C / min, the temperature of the water bath kettle is 95 - 105°C, the heat preservation time for acid solution etching treatment is 25 - 35 min, taking it out of the acid solution, and rinsing it with deionized water 3 - 5 times; The acid solution includes the following components: 80 - 100 g / L of sulfuric acid, and deionized water is added to 1 L.

7. Application of the high-entropy oxide anode prepared by the method according to any one of claims 3 to 6 in the fields of hydrometallurgy, organic synthesis, water electrolysis, sewage treatment, cathodic protection, etc.

Images