Dual-function self-supporting electrode for alkaline electrolyzed water as well as preparation method and application of dual-function self-supporting electrode

Abstract

The invention provides a difunctional self-supporting electrode for alkaline electrolyzed water as well as a preparation method and application of the difunctional self-supporting electrode. The preparation method of the difunctional self-supporting electrode for alkaline electrolyzed water comprises the following steps: carrying out constant-potential electro-deposition on foamed nickel in a cobalt nitrate metal precursor solution to obtain Co (OH) 2 / NF; placing the CoP / NF in a porcelain boat, placing the porcelain boat at the downstream of a tubular furnace, placing the porcelain boat containing sodium hypophosphite at the upstream of the tubular furnace, and heating for a period of time to obtain CoP / NF; and performing constant-potential electrodeposition on the CoP / NF in a mixed solution of ferric nitrate, cobalt nitrate and aluminum nitrate to obtain CoFeAl / CoP / NF, and performing continuous cyclic voltammetry on the obtained CoFeAl / CoP / NF in an alkaline solution to obtain the dual-function self-supporting electrode for alkaline electrolyzed water. The method has the advantages of simple process, low cost, high benefit and low energy consumption in the production process. The dual-function self-supporting electrode for alkaline electrolyzed water prepared by the method has good OER and HER dual-function attributes, and is high in stability.

Description

Technical Field

[0001] The invention relates to electrode technology, and in particular to a dual-function self-supporting electrode for alkaline water electrolysis, and a preparation method and application thereof. Background Art

[0002] AEM (anion exchange membrane) alkaline water electrolysis technology is a clean energy conversion method that produces hydrogen and oxygen through electrochemical reactions in alkaline media. The process relies on two key electrode reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In an alkaline environment, OER occurs at the anode, and the reaction mechanism involves the decomposition of water molecules to generate oxygen, protons (H + ) and electron (e - ), which requires a high overpotential and is the main source of energy consumption in the entire water electrolysis process. Therefore, it is crucial to develop efficient OER catalysts. HER occurs at the cathode and generates hydrogen by reducing water molecules. Under alkaline conditions, the kinetics of HER are relatively slow because in alkaline media, water molecules must first dissociate to produce hydroxide (OH - ) and protons, which then combine with electrons to generate hydrogen. Therefore, an efficient HER catalyst is also critical.

[0003] Although precious metal catalysts (such as platinum, gold and ruthenium) have been widely used in cathode HER, their inherent scarcity and high cost limit their widespread application. Among the many transition metal materials, nickel-based, iron-based and cobalt-based hydroxides, oxides and phosphides are particularly common in OER. However, their catalytic activity needs to be improved. The advantage of AEM technology is that it can operate under relatively mild alkaline conditions, avoiding the corrosion problem of acidic electrolytes on equipment, and also provides opportunities for the application of non-precious metal catalysts. However, the catalytic performance of OER and HER under alkaline conditions still needs to be further optimized, especially in terms of durability and cost-effectiveness. By developing efficient and low-cost catalysts, AEM alkaline water electrolysis technology is expected to become one of the feasible paths for large-scale hydrogen production. Summary of the invention

[0004] The purpose of the present invention is to propose a method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis in view of the above problems, which has the advantages of simple process, low cost, high efficiency and low energy consumption in the production process. The bifunctional self-supporting electrode for alkaline water electrolysis prepared by the method has good OER and HER bifunctional properties and strong stability.

[0005] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a dual-function self-supporting electrode for alkaline water electrolysis, comprising the following steps:

[0007] S1. Using nickel foam as a deposition electrode, constant potential electrodeposition is performed in a cobalt nitrate metal precursor solution, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0008] S2, Co(OH)2 / NF is placed in a porcelain boat and placed downstream of the tube furnace, and the porcelain boat containing sodium hypophosphite is placed upstream of the tube furnace, heated, maintained for a period of time, and the tube furnace is cooled to room temperature, and CoP / NF is taken out;

[0009] S3, using CoP / NF as a deposition working electrode, performing constant potential electrodeposition in a mixed solution of iron nitrate, cobalt nitrate and aluminum nitrate, and then drying the deposited sample to obtain CoFeAl / CoP / NF;

[0010] S4. CoFeAl / CoP / NF is used as an activated working electrode and electrolytic etching is performed by continuous cyclic voltammetry in an alkaline solution. Aluminum reacts under strong alkaline conditions to form aluminate ions that are easily soluble in water, which are then removed and dried to obtain a bifunctional self-supporting electrode D-CoFe / CoP / NF for alkaline water electrolysis.

[0011] Furthermore, the nickel foam is ultrasonically washed with acetone, hydrochloric acid, anhydrous ethanol and water in sequence before electrodeposition, and is placed in an oven for drying.

[0012] Furthermore, the hydrochloric acid is 1-3 mol / L, such as 1 mol / L, 2 mol / L and 3 mol / L.

[0013] Furthermore, the oven drying temperature is 50-60°C.

[0014] Furthermore, the size of the nickel foam described in step S1 is 1×2 cm to 5×6 cm.

[0015] Furthermore, the concentration of the cobalt nitrate solution in step S1 is 25-50 mmol / L, for example, 25 mmol / L and 50 mmol / L.

[0016] Furthermore, the potential of the constant potential electrodeposition in step S1 is -1.5 to 0.5 V relative to the reference electrode, preferably -1.0 V relative to the reference electrode, and the deposition time is 10 to 20 min.

[0017] Furthermore, the mass of the sodium hypophosphite in step S2 is 1 to 1.5 g / cm 2 Nickel foam, e.g. 1g / cm 2 Nickel foam, 1.2g / cm 2 Nickel foam, 1.5g / cm 2 The nickel foam of the present invention controls the quality of cobalt phosphide by controlling the content of sodium hypophosphite.

[0018] Furthermore, the heating in step S2 is performed at a rate of 2 to 3° C. per minute to a temperature of 350 to 400° C.

[0019] Furthermore, the holding time in step S2 is 2 to 2.5 hours.

[0020] Furthermore, in step S2, argon gas is introduced into the tubular furnace from upstream at a flow rate of 30 to 50 mL / min.

[0021] Furthermore, in the ferric nitrate, cobalt nitrate and aluminum nitrate solutions in step S3, the concentration of ferric nitrate is 25-50 mmol / L, the concentration of cobalt nitrate is 25-50 mmol / L, and the concentration of aluminum nitrate is 25-50 mmol / L.

[0022] Furthermore, the potential of the constant potential electrodeposition in step S3 is -1.5 to 0.5 V relative to the reference electrode, preferably -1.0 V relative to the reference electrode, and the deposition time is 10 to 20 min, for example 10 min, 15 min, 20 min. The present invention controls the loading amount of the catalyst by controlling the deposition time.

[0023] Furthermore, the alkali in the alkali solution in step S4 is sodium hydroxide and / or potassium hydroxide, and the concentration of the alkali solution is 1-2 mol / L, for example, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L; the present invention controls the etching rate and degree by controlling the alkali concentration.

[0024] Furthermore, the continuous cyclic voltammetry in step S4 is performed in an interval of 0.1 to 0.6 V relative to the reference electrode, and the number of cycles is 500 to 600. The present invention controls the degree of defects of the catalyst by controlling the number of etching cycles.

[0025] Another object of the present invention is to disclose a dual-function self-supporting electrode for alkaline water electrolysis, which is prepared by the above method.

[0026] Another object of the present invention is to disclose an application of a bifunctional self-supporting electrode for alkaline water electrolysis in the fields of AEM alkaline water electrolysis for hydrogen and oxygen production, biomass conversion and nitrate wastewater treatment.

[0027] The present invention is used for alkaline water electrolysis dual-function self-supporting electrode, and its preparation method and application, compared with the prior art, has the following advantages:

[0028] 1) The present invention discloses a method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis. First, the nickel foam is ultrasonically washed with acetone, hydrochloric acid, anhydrous ethanol and water in sequence, and placed in an oven for drying for standby use; the nickel foam after pretreatment is used as a deposition electrode, and a constant potential electrodeposition reaction is carried out in a cobalt nitrate metal precursor solution, and Co(OH)2 / NF is dried. Then, the obtained Co(OH)2 / NF is placed in a porcelain boat and placed downstream of a tube furnace, and a porcelain boat containing sodium hypophosphite is placed upstream of the tube furnace, and argon gas is introduced from the upstream at a flow rate of 30 to 50 mL / min. Heat, keep for a period of time, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF. Then, CoP / NF is used as a deposition working electrode, and constant potential electrodeposition is carried out in a mixed solution of iron nitrate, cobalt nitrate and aluminum nitrate. The sample is dried to obtain CoFeAl / CoP / NF, and continuous cyclic voltammetry is carried out in a 1 to 2 mol / L potassium hydroxide solution, and then D-CoFe / CoP / NF is dried. The self-supporting electrode prepared by the electrodeposition method of the present invention has the advantages of simple process, low cost, high benefit and low energy consumption in the production process.

[0029] 2) Bimetallic electrocatalysts can regulate electronic structure and synergy between metals. Specifically, changes in metal-metal bond lengths produce strain effects, thereby changing the electronic structure. Defect engineering can regulate the local surface microstructure, electronic structure, conductivity and charge distribution of the catalyst, thereby forming a low barrier and improving activity and stability. The present invention etches bimetallic nanosheets to generate defects and increase the active area of ​​the electrochemical reaction, and as a pure non-precious metal, it has excellent HER and OER activity and stability.

[0030] 3) The defect-rich self-supporting catalyst prepared by the present invention is in the form of nanosheets, the non-precious metal elements are evenly distributed inside, obvious defects are generated, and it has good stability.

[0031] In summary, the bifunctional self-supporting electrode for alkaline water electrolysis of the present invention has good application prospects and large-scale promotion potential in the fields of AEM alkaline water electrolysis for hydrogen and oxygen production, biomass conversion, and nitrate wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1is a scanning electron microscope (SEM) image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1;

[0033] Figure 2 is an energy dispersive X-ray spectroscopy (EDS) elemental mapping diagram of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1;

[0034] Figure 3 is a high-resolution transmission electron microscopy (HRTEM) image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1;

[0035] Figure 4 This is a transmission electron microscope image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1, and the heterojunction structure of CoP and cobalt-iron nanosheets can be clearly seen.

[0036] Figure 5 The geometric area current activity diagram (LSV curve of electrocatalytic OER) of the bifunctional self-supporting electrode for alkaline water electrolysis, CoP / NF catalyst and OER catalyst benchmark IrO2 / NF prepared in Example 1;

[0037] Figure 6 The geometric area current activity diagram (LSV curve of electrocatalytic HER) of the bifunctional self-supporting electrode for alkaline water electrolysis, CoP / NF catalyst and HER catalyst benchmark Pt / C / NF prepared in Example 1;

[0038] Figure 7 It is the geometric area current activity diagram (LSV curve of AEM electrolytic cell) of the bifunctional self-supporting electrode combination of cathode and cathode and Pt / C / NF||IrO2 / NF combination for alkaline water electrolysis prepared in Example 1. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0040] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0041] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0042] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0043] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0044] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0045] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15 to 25°C.

[0046] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0047] Example 1

[0048] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0049] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0050] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0051] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.5 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0052] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0053] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0054] Figure 1 This is a scanning electron microscope (SEM) image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1. It can be seen that the synthesized D-CoFe / CoP / NF is in the shape of uniform nanosheets and grows vertically on the surface of nickel foam.

[0055] Figure 2 It is the transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) element mapping diagram of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1, which proves that the synthesized sample is composed of iron, cobalt, oxygen and phosphorus, and shows a uniform distribution.

[0056] Figure 3 This is a high-resolution transmission electron microscopy (HRTEM) image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1, from which obvious lattice fringes and some defect structures can be seen.

[0057] Figure 4 This is a transmission electron microscope image of the bifunctional self-supporting electrode for alkaline water electrolysis prepared in Example 1, and the heterojunction structure of CoP and cobalt-iron nanosheets can be clearly seen.

[0058] Figure 5 This is the geometric area current activity diagram (LSV curve of electrocatalytic OER) of the bifunctional self-supporting electrode for alkaline water electrolysis and the benchmark IrO2 / NF catalyst for OER prepared in Example 1 of the present invention. Test conditions: a mixed solution is prepared in a ratio of ethylene glycol: deionized water: isopropanol: Nafion (5wt.%) = 90: 750: 150: 10, and a dispersion with a catalyst content of 2 mg / mL is prepared with the above mixed solution. 1 mL of the dispersion is dropped onto a pre-treated nickel foam of 1×1 cm in size, dried in a drying oven at 60°C, and the OER activity is tested in a 1.0M KOH solution, and the LSV curve scanning rate is 2mV / s. By comparing the geometric area current density at the same potential, it can be seen that the geometric area current density value of the bifunctional self-supporting electrode for alkaline water electrolysis prepared by the present invention exceeds the benchmark IrO2 / NF and CoP / NF catalysts for OER, proving the superiority of this catalyst.

[0059] Figure 6This is the electrochemical active surface area current activity diagram (LSV curve of electrocatalytic HER) of the bifunctional self-supporting electrode for alkaline water electrolysis and the HER catalyst benchmark Pt / C / NF prepared in Example 1 of the present invention. Test conditions: a mixed solution is prepared in a ratio of ethylene glycol: deionized water: isopropanol: Nafion (5wt.%) = 90: 750: 150: 10, and a dispersion with a catalyst content of 2 mg / mL is prepared with the above mixed solution. 1 mL of the dispersion is dropped onto a pre-treated nickel foam of 1×1 cm in size, dried in a drying oven at 60°C, and the HER activity is tested in a 1.0M KOH solution, and the LSV curve scanning rate is 2mV / s. By comparing the geometric area current density at the same potential, it can be seen that the current density value of the bifunctional self-supporting electrode for alkaline water electrolysis prepared by the present invention exceeds the HER benchmark Pt / C / NF and CoP / NF catalysts, proving the superiority of this catalyst.

[0060] Figure 7 This is the electrochemical active surface area current activity diagram of the bifunctional self-supporting electrode combination for alkaline water electrolysis and the AEM flow electrolytic cell assembled with Pt / C / NF||IrO2 / NF prepared in Example 1 of the present invention. Test conditions: According to the above-mentioned method for preparing electrodes, a working electrode with a size of 2×2 cm is prepared, assembled in an AEM electrolytic cell, and the activity of the entire cell is tested in a 1.0M KOH solution, with an LSV curve scan rate of 2mV / s. By comparing the geometric area current density at the same potential, it can be seen that the current density value of the D-CoFe / CoP / NF||D-CoFe / CoP / NF combination prepared by the present invention exceeds the Pt / C / NF||IrO2 / NF combination, proving the superiority of the catalyst in the AEM flow electrolytic cell.

[0061] Example 2

[0062] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0063] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0064] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0065] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.0 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 50 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0066] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0067] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0068] Example 3

[0069] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0070] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0071] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0072] S3, placing the Co(OH)2 / NF obtained in step S2 in a porcelain boat and placing it downstream of the tube furnace, placing a porcelain boat containing 1.0 g of sodium hypophosphite upstream of the tube furnace, heating to 350°C at 3°C ​​per minute, maintaining for 2 hours, and cooling the tube furnace to room temperature, taking out and obtaining CoP / NF;

[0073] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 10 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0074] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0075] Example 4

[0076] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0077] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0078] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 10 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0079] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.5 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0080] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0081] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0082] Example 5

[0083] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0084] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0085] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1 V relative to the reference electrode, the deposition time is 10 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0086] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.0 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0087] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 10 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0088] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L potassium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0089] Example 6

[0090] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0091] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0092] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0093] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.5 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 3 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0094] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0095] S5, using the CoFeAl / CoP / NF obtained in S4 as an activated working electrode, continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution, with a cyclic voltammetry potential range of 0.1-0.6 V relative to the reference electrode, and after 500 cycles, the D-CoFe / CoP / NF was obtained by drying. S3 formed a transitional phosphated CoP, which reduced the conductivity of the catalyst and greatly affected the reaction efficiency of HER and OER.

[0096] Example 7

[0097] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0098] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0099] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0100] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.0 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2.5 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0101] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 25 mmol / L aluminum nitrate, the deposition potential is -1 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0102] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0103] Example 8

[0104] This embodiment discloses a dual-function self-supporting electrode for alkaline water electrolysis, and the preparation method thereof comprises the following steps:

[0105] S1. Wash the nickel foam with a size of 1×2 cm with acetone, 3 mol / L hydrochloric acid, anhydrous ethanol and water in sequence, and dry it in a 60°C oven for later use;

[0106] S2, using the treated nickel foam obtained in step S1 as a deposition working electrode, performing a constant potential electrodeposition reaction in a 50 mmol / L cobalt nitrate metal precursor solution, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain Co(OH)2 / NF;

[0107] S3, put the Co(OH)2 / NF obtained in step S2 in a porcelain boat and place it downstream of the tube furnace, place a porcelain boat containing 1.5 g of sodium hypophosphite upstream of the tube furnace, introduce argon gas from the upstream at a flow rate of 30 mL / min, increase the temperature to 350°C at 3°C ​​per minute, maintain for 2 hours, wait for the tube furnace to cool to room temperature, and take out to obtain CoP / NF;

[0108] S4, using the CoP / NF obtained in S3 as a deposition working electrode, and performing constant potential electrodeposition in a mixed solution of 50 mmol / L ferric nitrate, 50 mmol / L cobalt nitrate and 50 mmol / L aluminum nitrate, the deposition potential is -1.0 V relative to the reference electrode, the deposition time is 20 min, and then the deposited sample is dried to obtain CoFeAl / CoP / NF;

[0109] S5. The CoFeAl / CoP / NF obtained in S4 was used as an activated working electrode, and continuous cyclic voltammetry was performed in a 1.0 mol / L sodium hydroxide solution. The cyclic voltammetry potential range was 0.1-0.6 V relative to the reference electrode. After 500 cycles, D-CoFe / CoP / NF was obtained by drying. The heterojunction structure formed by CoP and the cobalt-iron bimetallic promoted the HER and OER reactions. In addition, the abundant vacancy defects increased the electrochemical active area of ​​the catalyst, thereby enhancing the catalytic performance.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis, characterized in that: The following steps are involved: S1. Using nickel foam as a deposition electrode, constant potential electrodeposition is performed in a cobalt nitrate metal precursor solution, and then the deposited sample is dried to obtain Co(OH)2 / NF; S2, Co(OH)2 / NF is placed in a porcelain boat and placed downstream of the tube furnace, and the porcelain boat containing sodium hypophosphite is placed upstream of the tube furnace, heated, maintained for a period of time, and the tube furnace is cooled to room temperature, and CoP / NF is taken out; S3, using CoP / NF as a deposition working electrode, performing constant potential electrodeposition in a mixed solution of iron nitrate, cobalt nitrate and aluminum nitrate, and then drying the deposited sample to obtain CoFeAl / CoP / NF; S4. Use CoFeAl / CoP / NF as an activated working electrode, perform continuous cyclic voltammetry for electrolytic etching in an alkaline solution, and then dry it to obtain a bifunctional self-supporting electrode D-CoFe / CoP / NF for alkaline water electrolysis.

2. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The foamed nickel is ultrasonically washed with acetone, hydrochloric acid, anhydrous ethanol and water in sequence before electrodeposition, and is placed in an oven for drying.

3. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The concentration of the cobalt nitrate solution in step S1 is 25-50 mmol / L; And / or, the potential of the constant potential electrodeposition in step S1 is -1.5 to 0.5 V relative to the reference electrode, and the deposition time is 10 to 20 min.

4. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The mass of the sodium hypophosphite in step S2 is 1 to 1.5 g / cm 2 Nickel foam; And / or, the heating in step S2 is to increase the temperature to 350-400° C. at 2-3° C. per minute; And / or, the holding time in step S2 is 2 to 2.5 hours; And / or, in step S2, argon gas is introduced into the tubular furnace from upstream.

5. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: In the ferric nitrate, cobalt nitrate and aluminum nitrate solutions in step S3, the concentration of ferric nitrate is 25-50 mmol / L, the concentration of cobalt nitrate is 25-50 mmol / L, and the concentration of aluminum nitrate is 25-50 mmol / L.

6. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The potential of the constant potential electrodeposition in step S3 is -1.5 to 0.5 V relative to the reference electrode, and the deposition time is 10 to 20 minutes.

7. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The alkali in the alkali solution in step S4 is sodium hydroxide and / or potassium hydroxide, and the concentration of the alkali solution is 1-2 mol / L.

8. The method for preparing a bifunctional self-supporting electrode for alkaline water electrolysis according to claim, characterized in that: The continuous cyclic voltammetry in step S4 is performed at a voltage range of 0.1 to 0.6 V relative to the reference electrode, and the number of cycles is 500 to 600.

9. A dual-function self-supporting electrode for alkaline water electrolysis, characterized in that: The method is prepared by any one of claims 1 to 8.

10. An application of the bifunctional self-supporting electrode for alkaline water electrolysis according to claim 9 in the fields of AEM alkaline water electrolysis for hydrogen and oxygen production, biomass conversion and nitrate wastewater treatment.

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