Ruthenium-nickel-based difunctional self-supporting electrode and preparation method and application thereof

Abstract

The invention discloses a ruthenium-nickel-based bifunctional self-supporting electrode and a preparation method and application thereof.The preparation method comprises the steps that nickel chloride hexahydrate, ruthenium chloride, terephthalic acid and triethylamine hydrochloride serve as solutes, N-dimethylformamide serves as a solvent, and a deposition electrolyte is prepared; the pretreated foamed nickel is immersed in the electrolyte to serve as a working electrode, a platinum net is selected as a counter electrode, an Ag / AgCl electrode is adopted as a reference electrode, and current of-10 mA to-20 mA is applied for deposition; and washing the loaded foamed nickel with DMF (Dimethyl Formamide), ultrapure water and ethanol after electro-deposition, and carrying out vacuum drying to obtain the ruthenium-nickel-based difunctional self-supporting electrode. The ruthenium-nickel-based self-supporting bifunctional electrocatalyst provided by the invention can be used for water decomposition reaction, has good HER activity and OER activity, and can achieve very large hydrogen evolution and oxygen evolution current density under relatively low overpotential.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation, and specifically relates to a ruthenium-nickel-based bifunctional self-supporting electrode and a preparation method and application thereof. Background Art

[0002] Water electrolysis is an efficient and sustainable method to obtain high-purity hydrogen from abundant water resources. Designing a stable and efficient bifunctional catalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for the development of hydrogen production technology. At present, precious metal catalysts (such as Pt and RuO2) have the best catalytic performance in water electrolysis. However, the high cost and poor stability of precious metals seriously restrict their industrial production and application. Therefore, reducing costs and improving durability are the focus of this catalyst research. Among them, ruthenium (Ru) is considered to be the most promising active material among precious metal materials due to its Pt-like electronic structure and relatively low price. Therefore, the introduction of Ru dopants in transition metal nickel-based compounds is of great significance for the design and development of self-supporting electrode materials and the optimization of their performance. However, current related research is more focused on the development of monofunctional catalysts for HER or OER. In practical applications, two different types of catalysts need to be designed, which increases the complexity of water electrolysis equipment. For example, a nickel foam-supported Ru-NiO hydrogen evolution reaction catalyst and its preparation method are disclosed in a Chinese patent document (application number 202210267431.9), which uses nickel nitrate hexahydrate as a nickel source, urea and ammonium fluoride as structure directing agents, and water as a solvent. The support is immersed in a solution for hydrothermal reaction to generate nickel hydroxide on the surface of nickel foam, and then ruthenium is loaded on the surface of nickel hydroxide by electrodeposition in a ruthenium trichloride aqueous solution. Finally, calcination is performed to convert nickel hydroxide into nickel oxide, but the catalytic performance is poor due to the less exposure of active sites. A few studies have excellent dual-functional catalysis of electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), such as the successful assembly of solar-driven alkaline electrolyzers in the article Inter-doped ruthenium–nickel oxide heterostructure nanosheets with dual active centers for electrochemical- / solar-driven overall water splitting, which provides more active sites for the application of (Ru-Ni)Ox electrocatalysts, but cannot be catalyzed at high current density, limiting its industrial application. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a ruthenium-nickel-based bifunctional self-supporting electrode and a preparation method and application thereof, wherein the provided electrode has both good HER activity and OER activity.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] The present invention provides a method for preparing a ruthenium-nickel-based bifunctional self-supporting electrode, comprising the following steps:

[0006] Preparation of deposition electrolyte: using N,N-dimethylformamide DMF as solvent, nickel chloride hexahydrate, ruthenium chloride, terephthalic acid and triethylamine hydrochloride as solutes to prepare the deposition electrolyte.

[0007] In order to improve the preparation convenience and efficiency of the electrolyte, preferably, the specific preparation method of the deposition electrolyte includes the following steps: firstly dissolving nickel chloride hexahydrate, ruthenium chloride, terephthalic acid and triethylamine hydrochloride in N,N-dimethylformamide (the dissolution can be accelerated by disturbance, such as stirring, ultrasonic treatment), to obtain a mixed solution; uniformly mixing the mixed solution with a ruthenium chloride DMF solution to obtain a deposition electrolyte;

[0008] The molar ratio of Ni to Ru in the deposition electrolyte is calculated to be 1:0.0025-0.007, the concentration of terephthalic acid is about 0.1-0.3 mol / L, the concentration of triethylamine hydrochloride is about 0.008-0.015 mol / L, and the concentration of nickel chloride hexahydrate is 0.1-0.4 mol / L;

[0009] Electrodeposition: After removing the oxide layer from the surface, immerse the nickel foam in the electrolyte as the working electrode, use a platinum mesh as the counter electrode, and use an Ag / AgCl electrode as the reference electrode. Apply a current of -10mA to -20mA for deposition for 58 to 62min (preferably 60min) to obtain the loaded nickel foam;

[0010] After electrodeposition, the loaded nickel foam is washed with DMF, ultrapure water and ethanol and dried in vacuo to obtain a ruthenium-nickel based bifunctional self-supporting electrode.

[0011] The present invention is based on a three-electrode deposition method, combined with the molar ratio of Ni and Ru in the electrolyte and the concentration control of triethylamine hydrochloride, to obtain a ruthenium-nickel-based bifunctional self-supporting electrode, which has good HER activity and OER activity and can achieve large hydrogen evolution and oxygen evolution current densities at relatively low overpotentials.

[0012] As a preferred embodiment of the preparation method of the present invention, the method for removing the oxide layer on the surface of the nickel foam comprises immersing the nickel foam in 2-3 mol / L hydrochloric acid, ultrapure water and ethanol solution in sequence and ultrasonicating for 15-20 minutes.

[0013] As a preferred embodiment of the preparation method of the present invention, the deposition current is 10-15 mA, and the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0025-0.004;

[0014] More preferably, the deposition current is 18-20 mA, and the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0045-0.0055.

[0015] Another object of the present invention is to overcome the deficiencies in the prior art and to provide a ruthenium nickel-based bifunctional self-supporting electrode prepared by a method for preparing a ruthenium nickel-based bifunctional self-supporting electrode (also referred to as a ruthenium nickel-based bifunctional self-supporting catalytic material or a ruthenium nickel-based bifunctional self-supporting catalyst in the present invention).

[0016] Another object of the present invention is to overcome the deficiencies in the prior art and provide a ruthenium-nickel-based bifunctional self-supporting electrode for use in electrochemical water separation of hydrogen and oxygen.

[0017] Beneficial effects of the present invention:

[0018] (1) The ruthenium-nickel-based bifunctional self-supporting catalytic material prepared by the present invention has a HER catalytic activity comparable to that of commercial Pt / C under both acidic and alkaline conditions, and its price is also significantly lower than that of commercial Pt / C.

[0019] (2) The ruthenium-nickel-based bifunctional self-supporting catalytic material prepared by the present invention has excellent catalytic performance and is in line with the concept of green development. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. 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 creative labor. Among them:

[0021] Figure 1 This is the HER activity diagram of the ruthenium-nickel-based bifunctional self-supporting electrode in an embodiment of the present invention.

[0022] Figure 2 This is the OER activity diagram of the ruthenium-nickel-based bifunctional self-supporting electrode in an embodiment of the present invention.

[0023] Figure 3 This is a SEM image of the morphology of the ruthenium-nickel-based bifunctional self-supporting electrode 0.5RuNi / NF-20 in Example 6 of the present invention.

[0024] Figure 4 This is a deposition comparison diagram of Example 6 of the present invention and Comparative Example 2.

[0025] Figure 5 This is the HER catalytic durability curve of the ruthenium-nickel based bifunctional self-supporting electrode tested by the CP method.

[0026] Figure 6This is the OER catalytic durability curve of the ruthenium-nickel based bifunctional self-supporting electrode tested by the CP method. DETAILED DESCRIPTION

[0027] In order to further understand the purpose, content and advantages of the present invention, the specific embodiments of the present invention are now described in detail as follows, but it is not limited to the following examples, and it is freely matched according to actual conditions. The endpoints and any values ​​of the scope disclosed in this article are not limited to the precise scope and value. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article.

[0028] The present invention provides a ruthenium-nickel-based bifunctional self-supporting electrode and a preparation method and application thereof, wherein the specific preparation method of the catalyst includes the following:

[0029] (1) Preparing pretreated nickel foam: immersing the nickel foam in 2-3 mol / L hydrochloric acid, ultrapure water and ethanol solution in ultrasound for 15-20 minutes to obtain pretreated nickel foam; the size of the nickel foam is: 1.0×2 cm 2 ~1.0×2.5cm 2 (The size used in the example is 1×2 cm 2 ), nickel foam comes from Suzhou Shengernuo Technology Co., Ltd.

[0030] (2) Preparation of electrolyte: Nickel chloride hexahydrate (NiCl2·6H2O), terephthalic acid (PTA) and triethylamine hydrochloride (Et3NHCl) are dissolved in N,N-dimethylformamide (DMF), and then stirred until fully dissolved (the stirring method commonly used in the art can be selected. In this embodiment, the solution is first stirred for 30 minutes and then placed in an ultrasonic bath for 120 minutes) to obtain a DMF mixed solution. The concentration of NiCl2·6H2O added is 0.1 mol / L (molar amount of NiCl2·6H2O / DMF volume, and the concentration can be between 0.1 and 0.4 mol / L). l / L range, and has little effect on electrode performance, 0.1mol / L is selected in the embodiment of the present invention), the amount of terephthalic acid added calculated by concentration is 0.1mol / L (molar amount of terephthalic acid / DMF volume, the concentration can fluctuate in the range of 0.1-0.3mol / L, and has little effect on electrode performance, 0.1mol / L is selected in the embodiment of the present invention), the amount of triethylamine hydrochloride added calculated by concentration is 0.01mol / L (molar amount of triethylamine hydrochloride / DMF volume, when the added amount is 0.008-0.015mol / L, it has little effect on electrode performance).

[0031] Take 20 ml of the above DMF mixed solution and 0.3-0.7 ml of 0.02 mol / L ruthenium chloride DMF solution, mix them evenly to obtain a deposition electrolyte. In order to facilitate faster mixing, a small amount of ultrapure water can be added before mixing, or the ruthenium chloride solution can be diluted. In the following example, 0.65 ml of ultrapure water is added.

[0032] (3) Preparation of ruthenium-nickel-based self-supporting bifunctional water electrolysis catalytic electrode material with ampere-level current density: The pretreated nickel foam was immersed in the electrolyte as the working electrode, a platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. The three-electrode system chronopotentiometry (CP) was used to apply different currents for deposition for 1 hour to obtain loaded nickel foam (the platinum mesh was sourced from Shanghai Leton Industrial Co., Ltd., and the electrodeposition voltage was 1 to 8 V, which was direct current).

[0033] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (for 4 to 6 hours, at a temperature of 50 to 60° C.) to obtain the electrode material.

[0034] (4) The prepared catalyst was electrochemically tested using a three-electrode electrolyzer reaction device to test its water decomposition hydrogen performance

[0035] Electrochemical water splitting performance evaluation: tested by Donghua electrochemical workstation

[0036] In the three-electrode system, the working electrode is nickel foam, the reference electrode is Ag / AgCl electrode, and the counter electrode is platinum mesh;

[0037] Among them, the three-electrode system studies the two half reactions of water electrolysis, including the reduction reaction at the cathode to produce hydrogen and the oxidation reaction at the anode to produce oxygen;

[0038] The device was tested at room temperature and pressure with 1 M KOH as the electrolyte;

[0039] The HER / OER performance was tested in a suitable potential range (-1 to -3 V) by linear sweep method (LSV).

[0040] Then the CV curves were tested continuously at different scan rates (-2 to -3 V);

[0041] Finally, the impedance of the catalyst was tested: the current density based on the macroscopic area of ​​the electrode was 500 / 1000 mA cm -2 As an indicator for evaluating the catalytic activity of the catalyst for hydrogen evolution reaction (HER); the current density based on the macroscopic area of ​​the electrode is 500 / 800 mA cm -2 As an indicator for evaluating the catalytic activity of the catalyst for oxygen evolution (OER).

[0042] In the embodiment of the present invention, the deposition effect is sensitive to the deposition time. When the deposition time fluctuates between 58 and 62 minutes, the effect on the deposition effect is small, and the effect on the performance is generally within the range of ±2%. However, if the time exceeds this range, it will have a greater impact on the product performance (generally above ±5%).

[0043] In the embodiment of the present invention, when the deposition current is 18-20 mA, the product performance obtained by the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0045-0.0055 is relatively better than that of the electrode without ruthenium and pure loaded Ni (see the electrode NiOx / NF-15 prepared in the optimal embodiment of the prior application patent with application number 202411507889.2, the optimal embodiment means that all parameters are the most preferred) HER activity and OER activity (for OER, driving 500 / 800 mA cm in 1 M KOH electrolyte) -2 The overpotentials of the current density are 530mV and 600mV respectively. For HER, driving 500 / 1000mA cm in 1M KOH electrolyte -2 The overpotentials of the current densities are lower than 150 mV and 160 mV, respectively; for OER, driving 500 / 800 mA cm in 1 M KOH electrolyte -2 The overpotentials of the current densities are lower than 420 mV and 450 mV, respectively.

[0044] In the embodiment of the present invention, when the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0025-0.004, the deposition current is controlled to be 10-15 mA, and the obtained electrode product has both good HER activity and OER activity. For HER, the electrode product is driven at 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are lower than 180 mV and 230 mV, respectively; for OER, driving 500 / 800 mA cm in 1 M KOH electrolyte -2 The overpotentials of the current densities are lower than 450mV and 470mV, respectively.

[0045] The following is further described in detail with reference to some specific embodiments and comparative examples:

[0046] Embodiment 1:

[0047] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixture of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.3 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was 1:0.003). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -10 mA for deposition for 1 h.

[0048] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and vacuum dried (time 4-6h, temperature 50-60°C) to obtain the ruthenium nickel-based bifunctional self-supporting catalyst S1 (also referred to as 0.3RuNi / NF-10, or 0.3RuNi / NF-10mA1h).

[0049] (2) After the above catalysts were subjected to electrochemical water decomposition hydrogen / oxygen evolution tests, it was found that S1 had certain catalytic performance;

[0050] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current density are 176 / 201 mV respectively;

[0051] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 424 / 448 mV respectively.

[0052] Embodiment 2:

[0053] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixture of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.3 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was 1:0.003). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -15 mA for deposition for 1 h.

[0054] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (time 4-6h, temperature 50-60°C) to obtain catalyst S2 (also referred to as 0.3RuNi / NF-15, or 0.3RuNi / NF-15mA1h).

[0055] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S2 had certain catalytic performance.

[0056] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current density are 165 / 197 mV respectively;

[0057] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are 445 / 468 mV, respectively.

[0058] Embodiment 3:

[0059] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixture of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.3 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was 1:0.003). A platinum mesh was used as the counter electrode and an Ag / AgCl electrode was used as the reference electrode.

[0060] The three-electrode system chronopotentiometry (CP) was used to apply -20 mA current for deposition for 1 h. After electrodeposition, the loaded nickel foam was repeatedly washed with DMF, ultrapure water and ethanol. After vacuum drying (time 4-6 h, temperature 50-60°C), catalyst S3 (also referred to as 0.3RuNi / NF-20, or 0.3RuNi / NF-20mA1h) was obtained.

[0061] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S3 had certain catalytic performance.

[0062] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current density are 190 / 234 mV respectively;

[0063] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 459 / 490 mV, respectively.

[0064] Embodiment 4:

[0065] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixture of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.5 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was 1:0.005). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -10 mA for deposition for 1 h.

[0066] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (time 4-6h, temperature 50-60°C) to obtain S4 (also referred to as 0.5RuNi / NF-10, or 0.5RuNi / NF-10mA1h).

[0067] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S4 had certain catalytic performance.

[0068] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2The overpotentials of the current densities are 180 / 211 mV, respectively.

[0069] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 522 / 579 mV, respectively.

[0070] Embodiment 5:

[0071] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixed solution of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.5 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was calculated to be 1:0.005). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -15 mA for deposition for 1 h.

[0072] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (time 4-6h, temperature 50-60°C) to obtain S5 (also referred to as 0.5RuNi / NF-15, or 0.5RuNi / NF-15mA1h).

[0073] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S5 had certain catalytic performance.

[0074] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are 120 / 165 mV, respectively.

[0075] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are 500 / 549 mV, respectively.

[0076] Embodiment 6:

[0077] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixed solution of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.5 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was calculated to be 1:0.005). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -20 mA for deposition for 1 h.

[0078] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (time 4-6h, temperature 50-60°C) to obtain catalyst S6 (also referred to as 0.5RuNi / NF-20, or 0.5RuNi / NF-20mA1h).

[0079] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S6 had certain catalytic performance.

[0080] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 102 / 136 mV respectively.

[0081] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 408 / 417 mV respectively.

[0082] Based on this example, other conditions remain unchanged, and the deposition current is adjusted to -25 mA. For HER, the catalyst drives 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current density are 186 / 260 mV, respectively; for OER, the catalyst drives 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are 530 / 610 mV, respectively.

[0083] Catalyst HER activity diagram see Figure 1 ,It can be seen from the figure that according to η500-HER, the catalytic performance of these catalysts is in the following order: 0.5RuNi / NF-20>0.5RuNi / NF-15>0.3RuNi / NF-10>0.3RuNi / NF-15>0.5RuNi / NF-10>0.3RuNi / NF-20>0.7RuNi / NF-20;

[0084] According to η1000-HER, the order of catalytic performance is: 0.5RuNi / NF-20>0.5RuNi / NF-15>0.3RuNi / NF-10>0.3RuNi / NF-15>0.5RuNi / NF-10>0.3RuNi / NF-20>0.7RuNi / NF-20;

[0085] Catalyst OER activity diagram see Figure 2, it can be seen that according to η500-OER, the catalytic performance of these catalysts is in the following order: 0.5RuNi / NF-20>0.5RuNi / NF-15>0.3RuNi / NF-10>0.3RuNi / NF-15>0.5RuNi / NF-10>0.3RuNi / NF-20>0.7RuNi / NF-20;

[0086] According to η800-OER, the order of catalytic performance is: 0.5RuNi / NF-20>0.5RuNi / NF-15>0.3RuNi / NF-10>0.3RuNi / NF-15>0.5RuNi / NF-10>0.3RuNi / NF-20>0.7RuNi / NF-20.

[0087] The morphology and structure SEM image of the bifunctional catalyst 0.5RuNi / NF-20 is shown in Figure 2. Figure 3 As shown in the figure, the interlaced ultra-thin nanosheets are stacked and uniformly grown on the NF surface. The electrochemical test results show that the ruthenium nickel-based self-supporting electrode prepared under high deposition current has good catalytic activity. This can be attributed to the nanoflower-like structure composed of a large number of interlaced nanosheets, which is conducive to more fully exposing the electrode catalytic active surface area, increasing the contact area between the electrolyte and the catalyst in the catalytic reaction, and thus accelerating the overall catalytic reaction rate of the electrode.

[0088] Embodiment 7:

[0089] (1) The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a mixed solution of 20 mL of DMF mixed solution doped with 0.65 mL of ultrapure water and 0.7 mL of ruthenium chloride solution (the molar ratio of Ni to Ru in the electrolyte was calculated to be 1:0.007). A platinum mesh was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a current of -20 mA for deposition for 1 h.

[0090] After electrodeposition, the loaded nickel foam is repeatedly washed with DMF, ultrapure water and ethanol, and then vacuum dried (time 4-6h, temperature 50-60°C) to obtain S7 (also referred to as 0.7RuNi / NF-20, or 0.7RuNi / NF-20mA1h).

[0091] (2) After the above catalysts were subjected to electrochemical water decomposition and hydrogen / oxygen evolution tests, it was found that S5 had certain catalytic performance.

[0092] For HER, the catalyst drove 500 / 1000 mA cm in 1 M KOH electrolyte. -2 The overpotentials of the current densities are 211 / 315 mV respectively.

[0093] For OER, the catalyst drove 500 / 800 mA cm in 1 M KOH electrolyte. -2 The overpotentials for the current densities are 540 / 620 mV, respectively.

[0094] Comparative Example 1 (the difference from Example 1 is that the addition amount of triethylamine hydrochloride in the DMF mixed solution is calculated to be 0.03 mol / L):

[0095] Nickel chloride hexahydrate (0.1 mol / L), terephthalic acid (0.1 mol / L) and triethylamine hydrochloride (0.03 mol / L) were dissolved in N,N-dimethylformamide, stirred and ultrasonically treated to prepare an initial electrolyte; however, crystals were precipitated after standing overnight.

[0096] Comparative Example 2 (the difference from Example 6 is that the addition amount of triethylamine hydrochloride in the DMF mixed solution is calculated as 0.02 mol / L)

[0097] Nickel chloride hexahydrate (0.1 mol / L), terephthalic acid (0.1 mol / L) and triethylamine hydrochloride (0.02 mol / L) were dissolved in N,N-dimethylformamide, stirred and ultrasonically treated to prepare an initial electrolyte;

[0098] The pretreated nickel foam was immersed in an electrolyte as a working electrode. The electrolyte was a 20 mL DMF mixed solution doped with 0.65 mL ultrapure water and 0.5 mL ruthenium chloride solution. A platinum mesh was used as the counter electrode and an Ag / AgCl electrode was used as the reference electrode. A three-electrode system chronopotentiometry (CP) was used to apply a -20 mA current for 1 h.

[0099] Compared with Example 6, Figure 4 As shown, the active material in Comparative Example 2 (the sample on the left in the figure) grew unevenly and green material precipitated.

[0100] In addition, the present invention also uses the CP method to measure the durability of the 0.5RuNi / NF-20 electrode prepared in Example 6. Specifically, at 1 mol·L -1 In KOH solution, at 200 mA cm -2 The CP curves of HER and OER of 0.5RuNi / NF-20 electrode were tested at constant current density. Figure 5 , 6 It can be seen that the 0.5RuNi / NF-20 electrode exhibits good HER and OER activity durability.

[0101] The above is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, shall be covered within the protection scope of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for preparing a ruthenium-nickel based bifunctional self-supporting electrode, characterized in that: include, Preparation of deposition electrolyte: using DMF as solvent, nickel chloride hexahydrate, ruthenium chloride, terephthalic acid and triethylamine hydrochloride as solutes to prepare deposition electrolyte; calculating the molar ratio of Ni to Ru in the deposition electrolyte to be 1: 0.0025-0.007, the concentration of terephthalic acid to be 0.1-0.3 mol / L, the concentration of triethylamine hydrochloride to be 0.008-0.015 mol / L, and the concentration of nickel chloride hexahydrate to be 0.1-0.4 mol / L; Electrodeposition: After removing the oxide layer from the surface, immerse the nickel foam in the deposition electrolyte as the working electrode, use a platinum mesh as the counter electrode, and use an Ag / AgCl electrode as the reference electrode. Apply a current of -10mA to -20mA for deposition for 58 to 62min to obtain the loaded nickel foam. Post-treatment: The loaded nickel foam was washed with DMF, ultrapure water and ethanol, and vacuum dried to obtain a ruthenium-nickel based bifunctional self-supporting electrode.

2. The method for preparing the ruthenium-nickel based bifunctional self-supporting electrode according to claim 1, characterized in that: The method for removing the oxide layer on the surface of nickel foam comprises the following steps: immersing the nickel foam in 2-3 mol / L hydrochloric acid, ultrapure water and ethanol solution in sequence for 15-20 minutes for ultrasonic treatment to obtain the pretreated nickel foam.

3. The method for preparing the ruthenium-nickel based bifunctional self-supporting electrode according to claim 1, characterized in that: The electrodeposition time was 60 min.

4. The method for preparing the ruthenium-nickel based bifunctional self-supporting electrode according to claim 1, characterized in that: The deposition current is 10-15 mA, and the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0025-0.

004.

5. The method for preparing the ruthenium-nickel based bifunctional self-supporting electrode according to claim 1, characterized in that: The deposition current is 18-20 mA, and the molar ratio of Ni to Ru in the deposition electrolyte is 1:0.0045-0.0055.

6. The method for preparing the ruthenium-nickel based bifunctional self-supporting electrode according to claim 1, characterized in that: The concentration of triethylamine hydrochloride in the deposition electrolyte is 0.01 mol / L.

7. A ruthenium-nickel based bifunctional self-supporting electrode, characterized in that: The electrode is prepared by the method for preparing a ruthenium-nickel-based bifunctional self-supporting electrode as described in any one of claims 1 to 6.

8. Use of the ruthenium-nickel-based bifunctional self-supporting electrode as claimed in claim 7 in electrochemical water decomposition.

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