Cathode for alkaline water electrolysis hydrogen production and preparation method and application thereof

Abstract

The application relates to the technical field of water electrolysis cathode preparation, in particular to an alkaline water electrolysis hydrogen production cathode and a preparation method and application thereof. The preparation method comprises the following steps: mixing nickel powder, aluminum powder, platinum group metal powder and graphene powder to obtain mixed metal powder; adopting plasma spraying to spray the mixed metal powder to the surface of an electrode base material to form a coating, thereby obtaining a hydrogen evolution electrode; adopting alkaline solution to activate the hydrogen evolution electrode to form a catalytic layer on the surface of the electrode base material, thereby obtaining an alkaline water electrolysis hydrogen production cathode. The platinum group metal and the graphene are collectively melted with the nickel and the aluminum at high temperature, and then are sprayed to the surface of the electrode base material by the plasma spraying mode to form the coating, so that the coating and the base body have better combination, the coating is more uniform, the service life of the electrode is improved, and the hydrogen evolution potential is lower.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis cathode preparation technology, specifically to a cathode for alkaline water electrolysis hydrogen production, its preparation method, and its application. Background Technology

[0002] Water electrolysis is a promising hydrogen production method due to its high efficiency and ease of industrialization. It features simple operation, high product purity, no pollution, and economical raw material sources. Alkaline water electrolysis decomposes water by passing direct current through an alkaline aqueous solution, producing hydrogen at the cathode (hydrogen evolution electrode) and oxygen at the anode (oxygen evolution electrode). The theoretical voltage required for water electrolysis is 1.23V, but in practical applications, the voltage required for water decomposition is higher than this theoretical value. This additional voltage is called overpotential. The overpotential present at the cathode (hydrogen evolution) and anode (oxygen evolution) increases actual energy consumption, becoming a bottleneck restricting the development of water electrolysis in engineering fields. Therefore, it is necessary to reduce the overpotential to make the water decomposition reaction more energy-efficient and effective.

[0003] Alkaline water electrolysis for hydrogen production is a widely adopted industrial technology due to its mature technology and relatively low cost. Industrially, the cathode catalyst for alkaline water electrolysis for hydrogen production mainly uses Raney nickel coating, which has a high hydrogen evolution potential, resulting in high hydrogen production costs and hindering the industrial-scale production of hydrogen. Existing technologies generally use non-precious metal materials to dope the Raney nickel coating to reduce the hydrogen evolution potential of the cathode material. However, because these non-precious metal materials are applied to the electrode substrate surface in the form of droplets or solutions, the coating adhesion is often poor. Over time or at high electrolysis current densities, the coating may peel off, leading to voltage increases and insufficient electrode lifespan. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of poor adhesion and limited electrode life of existing non-precious metal modified Raney nickel coatings, thereby providing a cathode for alkaline water electrolysis hydrogen production, its preparation method and application.

[0005] The technical solution of this invention:

[0006] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps: mixing nickel powder, aluminum powder, platinum group metal powder and graphene powder to obtain a mixed metal powder; spraying the mixed metal powder onto the surface of an electrode substrate using plasma spraying to form a coating, thereby obtaining a hydrogen evolution electrode; and activating the hydrogen evolution electrode with an alkaline solution to form a catalytic layer on the surface of the electrode substrate, thereby obtaining a cathode for alkaline water electrolysis hydrogen production.

[0007] The platinum group metal is one or more of Pt, Ru, Ir, Pd, and Rh; preferably, the platinum group metal is one or more of Pd, Ir, and Rh; more preferably, the platinum group metal is Rh.

[0008] The method for forming the coating by plasma spraying includes the following steps: preheating the electrode substrate, and then using a spray gun in a plasma chamber to heat and melt the mixed metal powder and spray it onto the surface of the preheated electrode substrate to form the coating.

[0009] The preheating temperature is 80–120°C, and the preheating time is 10–30 min; the melting temperature (i.e., particle temperature) is 1700°C–2500°C. The melting temperature varies depending on the platinum group metal doping. The melting temperature for Pt doping is at least 1800°C; for Ru, at least 2400°C; for Ir, at least 2500°C; for Pd, at least 1600°C; and for Rh, at least 2000°C.

[0010] The coating thickness is 30-100 μm.

[0011] Argon gas with a flow rate of 100–180 scfh, nitrogen gas with a flow rate of 80–120 scfh, and hydrogen gas with a flow rate of 60–90 scfh are introduced into the plasma chamber before and during spraying.

[0012] The spray gun has a power of 90kW, a spraying distance of 10cm, a spraying angle of 80-95°, and a powder feeding rate of 100g / min.

[0013] The linear moving speed of the spray gun is 3-10 mm / s, and the number of spraying passes is 1-5.

[0014] The step of forming the coating by plasma spraying further includes a surface roughening treatment of the electrode substrate. The surface roughening treatment involves, before preheating, sequentially subjecting the electrode substrate to sandblasting and washing to obtain a roughened electrode substrate. Preferably, the sandblasting is performed using a sandblasting medium to blast the surface of the electrode substrate; the sandblasting medium is 100-mesh or 200-mesh corundum abrasive, and the number of sandblasting passes is 1-3 times, covering the front or both sides of the electrode substrate. The washing treatment is an acid pickling or water washing treatment, and the acid solution used in the acid treatment is any one or a mixture of several of oxalic acid, sulfuric acid, and hydrochloric acid; preferably, the acid solution is sulfuric acid with a concentration of 2.5wt%-4.0wt%.

[0015] The total loading of nickel and aluminum elements on the electrode substrate surface in the hydrogen evolution electrode is 272-372 g / m². 2 The mass ratio of nickel to aluminum is (3-10):(1-6), preferably (5-7):(3-5), and more preferably 6:4; the loading of platinum group metals on the electrode substrate surface is 0.5-3 g / m².2 The graphene loading on the electrode substrate surface is 1-5 g / m². 2 .

[0016] The amount of each component in the raw material is 3-4 times the target loading.

[0017] The activation treatment step involves immersing the hydrogen evolution electrode in an alkaline solution, wherein the alkaline solution is an aqueous sodium hydroxide solution with a concentration of 10wt%-30wt%, the treatment temperature is 55-85℃, and the treatment time is 10-50h.

[0018] The electrode substrate is made of nickel or a nickel-iron alloy. Preferably, the electrode substrate is a woven or stretched mesh structure of nickel or a nickel-iron alloy; preferably, the wire diameter of the electrode substrate is 0.1-0.3 mm.

[0019] The graphene is graphene oxide.

[0020] A cathode for alkaline water electrolysis hydrogen production prepared by the method comprises an electrode substrate and a catalyst layer located on the surface of the electrode substrate, wherein the catalyst layer contains nickel, platinum group metals and graphene.

[0021] The application of the cathode for alkaline water electrolysis hydrogen production.

[0022] The technical solution of this invention has the following advantages:

[0023] 1. This patent discloses a method for preparing a cathode for alkaline water electrolysis hydrogen production. The method employs plasma spraying to coat platinum group metals, graphene, nickel, and aluminum onto the surface of an electrode substrate after high-temperature melting. Under the high-temperature melting effect of plasma spraying, the components form a homogeneous, fused body, which is then sprayed onto the electrode substrate at high speed. This results in better adhesion between the coating and the substrate, a more uniform coating, and suitability for large-scale industrial production of large-size electrodes. Platinum group metals can reduce the hydrogen evolution overpotential and extend the electrode's lifespan. Graphene can regulate the electrode's microstructure, reduce cracks in the catalytic layer after spraying, and improve the electrode's lifespan. Further alkaline activation treatment removes aluminum from the coating as completely as possible, forming a microporous catalytic layer that increases the specific surface area of ​​the hydrogen evolution electrode and improves its electrochemical performance. Furthermore, graphene has extremely low resistivity, allowing electrons to move very efficiently within it, resulting in excellent conductivity. Together with the platinum group metals, it plays a coordinated role in catalyzing hydrogen production. In summary, the method of this invention significantly improves the bonding strength between the platinum group metal and graphene-modified Raney nickel catalyst layer and the electrode substrate, significantly enhances the stability of the electrode under high current density, extends the electrode lifespan, and results in a lower hydrogen evolution potential. This solves the problems of poor bonding strength and limited electrode lifespan of existing non-precious metal modified Raney nickel coatings.

[0024] 2. The platinum group metal is one or more of Pt, Ru, Ir, Pd, and Rh; preferably, it contains at least one or more of Ir, Pd, and Rh, and more preferably, the platinum group metal is Rh, which significantly improves the electrode lifespan and significantly reduces the hydrogen evolution potential. Detailed Implementation

[0025] Example 1

[0026] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps:

[0027] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 7.0g of Pt powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2; 10.5g of graphene oxide powder is added to metal powder 2 and mixed for 2 hours to obtain metal powder 3.

[0028] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 1900℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 3 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Pt is 2.0 g / m³. 2 The graphene oxide loading is 3.2 g / m³. 2 .

[0029] S3. The hydrogen evolution electrode is activated by soaking it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Pt / graphene oxide / Raney nickel catalytic layer on the surface, which is the cathode for alkaline water electrolysis hydrogen production.

[0030] Example 2

[0031] This embodiment provides a method for preparing a cathode for alkaline water electrolysis hydrogen production. The difference between this method and Example 1 is that Pt powder is replaced with Pd powder in step S1, and the particle temperature is controlled at 1700℃ in step S2.

[0032] Example 3

[0033] This embodiment provides a method for preparing a cathode for alkaline water electrolysis hydrogen production. The difference between this method and Example 1 is that Pt powder is replaced with Ir powder in step S1, and the particle temperature is controlled at 2650℃ in step S2.

[0034] Example 4

[0035] This embodiment provides a method for preparing a cathode for alkaline water electrolysis hydrogen production. The difference between this method and Example 1 is that Pt powder is replaced with Rh powder in step S1, and the particle temperature is controlled at 2100℃ in step S2.

[0036] Example 5

[0037] This embodiment provides a method for preparing a cathode for alkaline water electrolysis hydrogen production. The difference between this method and Example 1 is that Pt powder is replaced with Ru powder in step S1, and the particle temperature is controlled at 2500℃ in step S2.

[0038] Example 6

[0039] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps:

[0040] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 1.75g ​​of Rh powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2; 10.5g of graphene oxide powder is added to metal powder 2 and mixed for 2 hours to obtain metal powder 3.

[0041] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 3 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Rh is 0.5 g / m³. 2 The graphene oxide loading is 3.2 g / m³. 2 .

[0042] S3. The hydrogen evolution electrode is activated by soaking it in a 10wt% NaOH solution at 60℃ for 30 hours to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Rh / graphene oxide / Raney nickel catalytic layer on the surface, which is the cathode for alkaline water electrolysis hydrogen production.

[0043] Example 7

[0044] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps:

[0045] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 10.15g of Rh powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2; 10.5g of graphene oxide powder is added to metal powder 2 and mixed for 2 hours to obtain metal powder 3.

[0046] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 3 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Rh is 2.9 g / m³. 2 The graphene oxide loading is 3.2 g / m³. 2 .

[0047] S3. The hydrogen evolution electrode is activated by soaking it in a 10wt% NaOH solution at 60℃ for 30 hours to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Rh / graphene oxide / Raney nickel catalytic layer on the surface, which is the cathode for alkaline water electrolysis hydrogen production.

[0048] Example 8

[0049] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps:

[0050] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 7.0g of Rh powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2; 4.55g of graphene oxide powder is added to metal powder 2 and mixed for 2 hours to obtain metal powder 3.

[0051] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 3 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Rh is 2.0 g / m³. 2 The graphene oxide loading is 1.3 g / m³. 2 .

[0052] S3. The hydrogen evolution electrode is activated by soaking it in a 10wt% NaOH solution at 60℃ for 30 hours to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Rh / graphene oxide / Raney nickel catalytic layer on the surface, which is the cathode for alkaline water electrolysis hydrogen production.

[0053] Example 9

[0054] A method for preparing a cathode for alkaline water electrolysis hydrogen production includes the following steps:

[0055] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 7.0g of Rh powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2; 16.8g of graphene oxide powder is added to metal powder 2 and mixed for 2 hours to obtain metal powder 3.

[0056] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 3 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Rh is 2.0 g / m³. 2 The graphene oxide loading is 4.8 g / m³. 2 .

[0057] S3. The hydrogen evolution electrode is activated by soaking it in a 10wt% NaOH solution at 60℃ for 30 hours to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Rh / graphene oxide / Raney nickel catalytic layer on the surface, which is the cathode for alkaline water electrolysis hydrogen production.

[0058] Comparative Example 1

[0059] This comparative example provides a method for preparing a cathode for alkaline water electrolysis hydrogen production, comprising the following steps:

[0060] S1, 735.3g of nickel powder and 490.1g of aluminum powder were uniformly mixed by mechanical ball milling for 5 hours at a speed of 40r / min to obtain metal powder 1.

[0061] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 1 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 .

[0062] S3. The hydrogen evolution electrode was activated by immersing it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, thus obtaining a porous hydrogen evolution electrode with a Raney nickel catalytic layer on the surface.

[0063] Comparative Example 2

[0064] This comparative example provides a method for preparing a cathode for alkaline water electrolysis hydrogen production, comprising the following steps:

[0065] S1, 735.3g of nickel powder and 490.1g of aluminum powder were uniformly mixed by mechanical ball milling for 5 hours at a speed of 40r / min to obtain metal powder 1.

[0066] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 1 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2.

[0067] S3. The hydrogen evolution electrode was activated by immersing it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, thus obtaining a porous hydrogen evolution electrode with a Raney nickel catalytic layer on the surface.

[0068] S4. The porous hydrogen evolution electrode with a Raney nickel catalyst layer on its surface is preheated to 350°C in a nitrogen atmosphere. A precursor solution with a mass fraction of 25% is formed by dissolving vanadium oxysulfate aqueous solution in deionized water and placed in an ultrasonic atomizer to generate droplets. The droplets are carried by nitrogen gas and sprayed onto the surface of the preheated porous hydrogen evolution electrode. The spraying time lasts for 3 minutes. After natural cooling, a porous hydrogen evolution electrode with a vanadium oxide / Raney nickel catalyst layer on its surface is obtained.

[0069] Comparative Example 3

[0070] This comparative example provides a method for preparing a cathode for alkaline water electrolysis hydrogen production, comprising the following steps:

[0071] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40r / min to obtain metal powder 1. 7.0g of Rh powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2.

[0072] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively, onto the preheated electrode substrate. Under rotating conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 2 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a 50μm thick coating. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the electrode substrate surface in the hydrogen evolution electrode was 351.0g / m². 2 The loading of Rh is 2.0 g / m³. 2 .

[0073] S3. The hydrogen evolution electrode was activated by immersing it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a Rh / Raney nickel catalytic layer on the surface.

[0074] Comparative Example 4

[0075] This comparative example provides a method for preparing a cathode for alkaline water electrolysis hydrogen production, comprising the following steps:

[0076] S1, 735.3g of nickel powder and 490.1g of aluminum powder are uniformly mixed by mechanical ball milling for 5 hours at a speed of 40 r / min to obtain metal powder 1; 10.5g of graphene oxide powder is added to the above metal powder 1 and mixed for 2 hours at the same speed to obtain metal powder 2'.

[0077] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. The roughened electrode substrate is then preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are respectively introduced into the plasma chamber onto the preheated electrode substrate. Under rotation, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feed rate to 100g / min, and the linear movement speed of the spray gun to 5mm / s. Metal powder 2' was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a 50μm thick coating. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the electrode substrate surface in the hydrogen evolution electrode was 351.0g / m². 2 The graphene oxide loading is 3.2 g / m³. 2 .

[0078] S3. The hydrogen evolution electrode was activated by immersing it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, resulting in a porous hydrogen evolution electrode with a graphene / Raney nickel catalytic layer on the surface.

[0079] Comparative Example 5

[0080] This comparative example provides a method for preparing a cathode for alkaline water electrolysis hydrogen production, comprising the following steps:

[0081] S1, 735.3g of nickel powder and 490.1g of aluminum powder were uniformly mixed by mechanical ball milling for 5 hours at a speed of 40r / min to obtain metal powder 1.

[0082] S2, using 100-mesh white corundum abrasive as the blasting medium, the electrode substrate is blasted three times on each of its front and back surfaces. Then, the blasted electrode substrate is acid-washed with 3wt% sulfuric acid for 1 hour to form a roughened electrode substrate. Next, the roughened electrode substrate is preheated at 100℃ for 30 minutes. Argon gas at a flow rate of 120 scfh, nitrogen gas at a flow rate of 100 scfh, and hydrogen gas at a flow rate of 60 scfh are introduced into the plasma chamber, respectively. The preheated electrode substrate is then rotated... Under the following conditions, the spray gun power was set to 90kW, the particle temperature to 2100℃, the spraying distance to 10cm, the spraying angle to 85°, the powder feeding rate to 100g / min, and the linear moving speed of the spray gun to 5mm / s. Metal powder 1 was heated and melted using the spray gun and then sprayed onto both sides of the electrode substrate to form a coating with a thickness of 50μm. The coating was applied in three passes to obtain a hydrogen evolution electrode. The total loading of nickel and aluminum elements on the surface of the electrode substrate in the hydrogen evolution electrode was 351.0g / m². 2 .

[0083] S3. The hydrogen evolution electrode was activated by immersing it in a 10wt% NaOH solution at 60℃ for 30h to form a catalytic layer on the surface of the electrode substrate, thus obtaining a porous hydrogen evolution electrode with a Raney nickel catalytic layer on the surface.

[0084] S4, 5.1 g of RhCl3·3H2O was added to 400 ml of deionized water and stirred until completely dissolved. Then, 3 g of graphene oxide was added and ultrasonically dispersed for 15 min to obtain a suspension. The suspension was transferred to a 1 L reactor and hydrothermally reacted at 180 °C for 4 h. After natural cooling and centrifugation, the resulting solid was washed with ultrapure water and ethanol and dried at 150 °C for 8 h to obtain the Rh / graphene catalyst. The above solid powder was dispersed in 100 mL of a 75% ethanol and naphthol mixed solution (volume ratio 95:5) and ultrasonically sonicated for 60 min to ensure uniform dispersion and form an ink solution. This ink solution was dropped onto the porous hydrogen evolution electrode with a Raney nickel catalyst layer obtained in S3. After drying, a porous hydrogen evolution electrode with a Rhodium and graphene-modified Raney nickel catalyst layer was obtained, wherein the Rh loading on the electrode substrate surface was 2.0 g / m². 2 The graphene catalyst loading was 3.2 g / m³. 2 .

[0085] Test case

[0086] The electrochemical performance of the hydrogen evolution electrodes obtained in Examples 1-9 and Comparative Examples 1-5 was tested using an electrochemical workstation.

[0087] The test system was a conventional three-electrode system, with the hydrogen evolution electrode as the working electrode, a nickel mesh as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was 30 wt% potassium hydroxide, and the temperature was 85 °C. The hydrogen evolution electrode was tested at 3 kA / m. 2 The hydrogen evolution potential at 10 kA / m 2 After 10 hours of continued electrolysis, the mass of the hydrogen evolution electrode before and after electrolysis was recorded, and the weight loss value of the hydrogen evolution electrode was calculated (less weight loss of the electrode before and after electrolysis indicates a longer electrode life and more stable performance). The results are shown in Table 1.

[0088] Table 1. Electrochemical Performance Tests

[0089] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Hydrogen evolution potential (V) -1.214 -1.219 -1.221 -1.201 -1.211 -1.216 -1.218 Enhanced lifespan weight loss (mg) 1.4 0.7 1.2 0.5 2.0 0.8 1.3 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Hydrogen evolution potential (V) -1.214 -1.217 -1.241 -1.223 -1.209 -1.233 -1.238 Enhanced lifespan weight loss (mg) 0.9 1.5 4.2 7.7 3.5 3.8 16.3

[0090] In Comparative Example 1, the Raney nickel catalyst layer resulted in a high hydrogen evolution potential at the hydrogen evolution electrode, leading to significant weight loss at high current densities. In Comparative Example 2, vanadium oxide particles were doped into the Raney nickel coating, which reduced the hydrogen evolution potential but increased weight loss at high current densities, resulting in poor electrode lifespan.

[0091] Comparative Example 3, which only doped with rhodium in the Raney nickel coating, showed visible cracks in the catalyst layer due to the lack of graphene, resulting in a high electrode weight loss value. Furthermore, the coating was prone to detachment after long-term bubble erosion, leading to a short lifespan. Comparative Example 4, which only doped with graphene oxide in the Raney nickel coating, also experienced deteriorated electrode lifespan and a high hydrogen evolution potential due to the lack of rhodium. Comparative Example 5, which used a drop-coated Rh / graphene catalyst doped with rhodium and graphene, exhibited extremely poor bonding between the doped elements, severe coating detachment, and an extremely short electrode lifespan.

[0092] Examples 1-5 of this application employ plasma spraying to dope Pt, Pd, Ir, Rh, Ru, and graphene into a Raney nickel catalyst layer, respectively. The hydrogen evolution electrode operates at 10 kA / m. 2 The weight loss at high current density is significantly reduced, the service life is significantly improved, and the hydrogen evolution potential is low. The type of platinum group metal affects the performance. Pd in ​​Example 2, Ir in Example 3, and Rh in Example 4 are preferred, resulting in lower electrode weight loss at high current density. Among them, the electrode weight loss of Example 4, which uses Rh as the platinum group metal, is the lowest, at 0.5 mg.

[0093] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a cathode for alkaline water electrolysis hydrogen production, characterized in that, Includes the following steps: Nickel powder, aluminum powder, platinum group metal powder and graphene oxide powder are mixed to obtain a mixed metal powder; the mixed metal powder is sprayed onto the surface of an electrode substrate by plasma spraying to form a coating, thus obtaining a hydrogen evolution electrode; the hydrogen evolution electrode is activated by alkaline solution to form a catalytic layer on the surface of the electrode substrate, thus obtaining a cathode for alkaline water electrolysis to produce hydrogen.

2. The preparation method according to claim 1, characterized in that, The platinum group metal is one or more of Pt, Ru, Ir, Pd, and Rh.

3. The preparation method according to claim 1, characterized in that, The method for forming the coating by plasma spraying includes the following steps: preheating the electrode substrate, and then using a spray gun in a plasma chamber to heat and melt the mixed metal powder and spray it onto the surface of the preheated electrode substrate to form the coating.

4. The preparation method according to claim 3, characterized in that, The preheating temperature is 80-120℃, and the preheating time is 10-30 min; the heating and melting temperature is 1700℃-2500℃.

5. The preparation method according to claim 3, characterized in that, Before and during spraying, argon gas with a flow rate of 100–180 scfh, nitrogen gas with a flow rate of 80–120 scfh, and hydrogen gas with a flow rate of 60–90 scfh are introduced into the plasma chamber.

6. The preparation method according to claim 3, characterized in that, The spray gun has a power of 90 kW, a spraying distance of 10 cm, a spraying angle of 80–95°, and a powder feeding rate of 100 g / min.

7. The preparation method according to claim 3, characterized in that, The linear moving speed of the spray gun is 3-10 mm / s, and the number of spraying passes is 1-5.

8. The preparation method according to claim 3, characterized in that, The step of forming the coating by plasma spraying further includes a step of surface roughening treatment of the electrode substrate, wherein the surface roughening treatment step is as follows: before the preheating treatment, the electrode substrate is subjected to sandblasting treatment and washing treatment in sequence to obtain a roughened electrode substrate.

9. The preparation method according to claim 1, characterized in that, The total loading of nickel and aluminum elements in the hydrogen evolution electrode on the electrode substrate surface is 272-372 g / m². 2 The mass ratio of nickel to aluminum is (3-10):(1-6), and the loading of platinum group metals on the electrode substrate surface is 0.5-3 g / m². 2 The graphene oxide loading on the electrode substrate surface is 1-5 g / m². 2 .

10. The preparation method according to claim 3, characterized in that, The coating thickness is 30-100 μm.

11. The preparation method according to claim 1, characterized in that, The activation treatment step involves immersing the hydrogen evolution electrode in an alkaline solution, wherein the alkaline solution is an aqueous sodium hydroxide solution with a concentration of 10wt%-30wt%, the treatment temperature is 55-85℃, and the treatment time is 10-50 h.

12. The preparation method according to claim 1, characterized in that, The electrode substrate is made of nickel or a nickel-iron alloy.

13. A cathode for alkaline water electrolysis to produce hydrogen, prepared by the method according to any one of claims 1-12, characterized in that, It includes an electrode substrate and a catalyst layer located on the surface of the electrode substrate, the catalyst layer containing nickel, platinum group metals and graphene oxide.

14. The application of the cathode for alkaline water electrolysis hydrogen production as described in claim 13 in alkaline water electrolysis hydrogen production.