Preparation method of copper-molybdenum modified nickel phosphate nanorod array and application thereof
By preparing copper@molybdenum modified nickel phosphate nanorod arrays on copper foam, the problem of low activity of hydrogen evolution catalysts in neutral solutions was solved, and efficient electrocatalytic hydrogen evolution performance in neutral electrolytes was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUAZHONG NORMAL UNIV
- Filing Date
- 2022-12-13
- Publication Date
- 2026-06-26
AI Technical Summary
The intrinsic activity and hydrogen evolution performance of hydrogen evolution catalysts in neutral solutions are low, making it difficult to meet commercialization requirements. In particular, the sluggish kinetics caused by water dissociation in neutral electrolytes is a major challenge.
Copper nanowire arrays were grown on copper foam using an impregnation method and an electroreduction method. Then, molybdenum-modified nickel phosphate was loaded onto the copper nanowires by electrodeposition to form a copper@molybdenum-modified nickel phosphate nanorod array, which increased the electrochemical active surface area and reactive centers.
In neutral electrolyte, copper@molybdenum modified nickel phosphate nanorod arrays exhibit excellent catalytic activity, low overpotential, and stable operation for 25 hours, making them suitable for the hydrogen evolution reaction in neutral water electrolysis.
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Figure CN116083943B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of neutral solution electrolysis of water for hydrogen evolution technology, and particularly relates to a method for preparing copper@molybdenum modified nickel phosphate nanorod arrays and their applications. Background Technology
[0002] Hydrogen production through water electrolysis is gradually becoming an important pathway due to its low pollution, rapid production speed, mild reaction conditions, and high purity. Traditional water electrolysis for hydrogen production mainly takes place in acidic and alkaline electrolyzers. However, the large-scale application of acidic and alkaline water electrolysis has been limited because hydrogen production under extreme pH conditions requires expensive anion / cation exchange membranes, and extreme pH values negatively impact the durability of the electrolyzer and electrocatalyst. Compared to acidic and alkaline water electrolysis, neutral water electrolysis offers a milder reaction environment, significantly reducing electrolyte corrosion of the electrolyzer and thus possessing greater application scope and development value. Once the technology is mastered, it means that the Earth's abundant neutral seawater resources can be fully utilized. Therefore, the development of highly active and stable water-splitting catalysts for hydrogen production in neutral electrolytes has attracted widespread attention.
[0003] Compared to hydrogen evolution in acidic solutions, the protons required for hydrogen evolution in neutral solutions primarily originate from water molecules. The sluggish kinetics caused by water dissociation are generally considered one of the main challenges in neutral hydrogen evolution. Nickel-phosphorus compounds are considered excellent electrocatalysts for hydrogen evolution due to their high catalytic activity and low cost. The introduction of phosphorus can modulate the electronic structure of nickel, reducing the water dissociation free energy and proton adsorption free energy during the hydrogen evolution reaction. However, due to the high ohmic loss and low ion concentration in neutral solutions, nickel-phosphorus compounds exhibit low intrinsic activity and hydrogen evolution performance, making them unsuitable for commercial applications. Therefore, modifying nickel-phosphorus compounds to improve their catalytic performance in neutral solutions is of great significance. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing copper@molybdenum modified nickel phosphate nanorod arrays and their applications, aiming to solve the problems mentioned in the background art.
[0005] The present invention is implemented as follows: a method for preparing a copper@molybdenum modified nickel phosphate nanorod array, comprising a copper@molybdenum modified nickel phosphate nanorod array, the method comprising the following steps:
[0006] Step 1: After washing and drying the copper hydroxide nanobundles / copper foam [Cu(OH)2 / CF] prepared by the impregnation method with deionized water, use it as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.50~1.50M sodium sulfate solution, the current density is -10~-50 mA / cm². 2 Copper hydroxide nanobundles / copper foam were electro-reduced at room temperature for 20-60 minutes, then washed with deionized water and dried to prepare copper nanowires / copper foam.
[0007] Step 2: Using copper nanowires / copper foam (Cu / CF) as the working electrode, graphite rods as the counter electrode, and saturated calomel electrodes as the reference electrode, an aqueous solution containing different concentrations of sodium hypophosphite, molybdate, divalent nickel salt, and metal complexing agent was used as the electrolyte. Nickel-molybdenum-phosphorus material was electrodeposited at a constant voltage of -0.8 to -1.2 V for 500 to 2000 seconds. Afterward, the sample was washed and dried with deionized water and ethanol to prepare a copper@molybdenum modified nickel phosphate nanorod array.
[0008] In a further technical solution, in step 2, the concentrations of sodium hypophosphite, molybdate, divalent nickel salt, and metal complexing agent are 0.50~1.50M, 0.01~0.10M, 0.03~0.20M, and 0.05~0.20M, respectively.
[0009] In a further technical solution, the diameter of the nanorods in the copper@molybdenum modified nickel phosphate nanorod array is 300~900nm.
[0010] Another objective of this invention is to provide an application of a copper@molybdenum modified nickel phosphate nanorod array prepared by a method for preparing such an array in the electrolysis of water in a neutral solution for hydrogen evolution.
[0011] A further technical solution, the specific steps of the application are as follows:
[0012] Using a copper@molybdenum modified nickel phosphate nanorod array as the working electrode, an electrocatalytic hydrogen evolution reaction was carried out in neutral three-electrode systems including phosphate buffer solution, sodium sulfate solution, acetate buffer solution, and carbonate buffer solution.
[0013] This invention provides a method for preparing copper@molybdenum modified nickel phosphate nanorod arrays. The electrode material is prepared by a combination of impregnation, electroreduction, and electrodeposition methods. First, copper nanowire arrays are grown on copper foam using impregnation and electroreduction methods. Then, molybdenum-modified nickel phosphate is loaded onto the copper nanowires using electrodeposition. The copper@molybdenum modified nickel phosphate nanorods have a diameter of 300-900 nm, and the nanorod array is uniformly distributed, effectively increasing the electrochemically active surface area and the number of reactive centers.
[0014] The prepared copper@molybdenum modified nickel phosphate nanorod array exhibited excellent catalytic activity as a working electrode for hydrogen evolution in neutral water electrolysis. In the neutral electrolyte, at current densities of 10 and 100 mA cm⁻¹, [the catalytic activity was observed]. -2 At that time, the minimum required overpotentials are 35 and 195 mV. Meanwhile, when the current density is 10 mA cm⁻¹... -2 At that time, the catalyst can operate stably for at least 25 hours. Attached Figure Description
[0015] Figure 1 The fabrication process for copper@molybdenum modified nickel phosphate nanorod arrays (Ni-Mo-P / Cu / CF);
[0016] Figure 2 In the image, (a) to (c) are scanning electron microscope (SEM) images of copper foam substrate (CF) at different magnifications, (d) to (f) are SEM images of Cu(OH)2 / CF at different magnifications, and (h) to (j) are SEM images of Cu / CF at different magnifications.
[0017] Figure 3 In the image, (a) to (c) are SEM images of Ni-Mo-P / Cu / CF obtained after electrochemical deposition at different magnifications, (d) is a low-magnification TEM image of Ni-Mo-P / Cu / CF, (e) is an HRTEM image of Ni-Mo-P / Cu / CF, and (f) to (k) are HAADF-STEM images of Ni-Mo-P / Cu / CF and corresponding EDX elemental distribution images.
[0018] Figure 4 (a) is the high-resolution nickel 2p spectrum of Ni-Mo-P / Cu / CF and Ni-P / Cu / CF, (b) is the high-resolution molybdenum 3d spectrum of Ni-Mo-P / Cu / CF, (c) is the high-resolution phosphorus 2p spectrum of Ni-Mo-P / Cu / CF and Ni-P / Cu / CF, and (d) is the XRD pattern of Ni-Mo-P powder.
[0019] Figure 5The results of electrochemical performance tests in a neutral electrolyte (i.e., 1.00 M phosphate buffer solution) are shown in (a) and (b), where (a) and (b) show the hydrogen evolution polarization curves and overpotential comparisons at corresponding current densities for Cu / CF, Ni-Mo-P / CF, Ni-Mo-P / Cu / CF, Ni-P / Cu / CF, and Pt / C / CF; (c) shows the Tafel slopes for Cu / CF, Ni-Mo-P / CF, Ni-Mo-P / Cu / CF, Ni-P / Cu / CF, and Pt / C / CF; and (d) shows the double-layer capacitance values for Cu / CF, Ni-Mo-P / CF, Ni-Mo-P / Cu / CF, Ni-P / Cu / CF, and Pt / C / CF.
[0020] Figure 6 (a) shows the electrochemical impedance spectroscopy (EIR) images of Cu / CF, Ni-Mo-P / CF, Ni-Mo-P / Cu / CF, and Ni-P / Cu / CF; (b) shows the EIR images of Ni-Mo-P / CF and Ni-Mo-P / Cu / CF in a neutral electrolyte at 10 mA cm⁻¹. -2 Stability tests were conducted using the current density.
[0021] Figure 7 This is a comparison of the electrocatalytic performance of the electrodes of samples 1-7 in neutral electrolyte. Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0023] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.
[0024] An embodiment of the present invention provides a method for preparing a copper@molybdenum modified nickel phosphate nanorod array, comprising a copper@molybdenum modified nickel phosphate nanorod array, the method comprising the following steps:
[0025] Step 1: After washing and drying the copper hydroxide nanobundles / copper foam [Cu(OH)2 / CF] prepared by the impregnation method with deionized water, use it as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.50~1.50M sodium sulfate solution, the current density is -10~-50 mA / cm². 2 Copper hydroxide nanobundles / copper foam were electroreduced at room temperature for 20-60 minutes, then washed with deionized water and dried to prepare copper nanowires / copper foam.
[0026] Step 2: Using copper nanowires / copper foam (Cu / CF) as the working electrode, graphite rods as the counter electrode, and saturated calomel electrodes as the reference electrode, an aqueous solution containing different concentrations of sodium hypophosphite, molybdate, divalent nickel salt, and metal complexing agent was used as the electrolyte. Nickel-molybdenum-phosphorus material was electrodeposited at a constant voltage of -0.8 to -1.2 V for 500 to 2000 seconds. Afterward, the sample was washed and dried with deionized water and ethanol to prepare a copper@molybdenum modified nickel phosphate nanorod array.
[0027] In this embodiment of the invention, the concentrations of sodium hypophosphite, molybdate, divalent nickel salt, and metal complexing agent are 0.50~1.50M, 0.01~0.10M, 0.03~0.20M, and 0.05~0.20M, respectively.
[0028] The diameter of the nanorods in the copper@molybdenum modified nickel phosphate nanorod array is 300~900 nm.
[0029] As a preferred embodiment of the present invention, the application of a copper@molybdenum modified nickel phosphate nanorod array prepared by a method for preparing a copper@molybdenum modified nickel phosphate nanorod array in the electrolytic desorption of hydrogen in a neutral solution is described in the following specific steps:
[0030] Using a copper@molybdenum modified nickel phosphate nanorod array as the working electrode, an electrocatalytic hydrogen evolution reaction was carried out in neutral three-electrode systems including phosphate buffer solution, sodium sulfate solution, acetate buffer solution, and carbonate buffer solution.
[0031] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0032] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0033] Copper foam was immersed in 3.00 M hydrochloric acid for 15 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was then dried in a 60°C oven for later use. Next, the hydrochloric acid-treated copper foam was immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed in a 60°C oven for 10 minutes. After 10 minutes, the beaker was removed, and the copper foam in the solution was turned over with tweezers. It was then placed back in the 60°C oven for another 10 minutes. The beaker was removed again, and the copper foam was removed with tweezers and rinsed sequentially with deionized water and ethanol. Finally, the copper foam was dried in a 65°C oven to obtain copper hydroxide nanobundles precursors grown on copper foam.
[0034] Step 2: Obtain copper nanowires using an electroreduction method:
[0035] Prepare a 1.00 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode, a saturated calomel electrode as the reference electrode, and a copper foam with copper hydroxide nanobundles grown in step 1, clamped with a platinum electrode clamp, as the working electrode. The reduction current density is -10 mA / cm². -2 Electroreduction was performed at room temperature for 50 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60°C to obtain a copper nanowire array grown on the copper foam.
[0036] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0037] A solution containing 0.05 M nickel sulfate hexahydrate, 0.01 M sodium molybdate dihydrate, 0.90 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 1000 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in a 65°C vacuum drying oven to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0038] Step 4: Using a copper@molybdenum modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0039] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0040] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0041] Copper foam was immersed in 1.00M hydrochloric acid for 25 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried at room temperature. The hydrochloric acid-treated copper foam was then immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed at room temperature, and after 20 minutes, the copper foam was turned over with tweezers and immersed for another 20 minutes. The copper foam was then removed with tweezers and rinsed sequentially with deionized water and ethanol. Finally, the copper foam was dried in a 65°C oven to obtain copper hydroxide nanobundles precursors grown on copper foam.
[0042] Step 2: Obtain copper nanowires using an electroreduction method:
[0043] Prepare a 0.50 M sodium sulfate solution, stir well, and use it as the electrolyte. Use a graphite rod as the counter electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode clamp to hold the copper foam with copper hydroxide nanobundles grown in step 1, as the working electrode. The reduction current density is -30 mA / cm². -2 Electroreduction was performed at room temperature for 30 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60°C to obtain a copper nanowire array grown on the copper foam.
[0044] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0045] A solution containing 0.05 M nickel sulfate hexahydrate, 0.03 M sodium molybdate dihydrate, 0.90 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 1200 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in a vacuum drying oven at 65 °C to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0046] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0047] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0048] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0049] Copper foam was immersed in 3.00 M hydrochloric acid for 15 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried in a 65°C oven. The hydrochloric acid-treated copper foam was then immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed at room temperature, and after 20 minutes, the copper foam was turned over with tweezers and immersed for another 20 minutes. The copper foam was then removed with tweezers and rinsed sequentially with deionized water and ethanol, and dried at room temperature to obtain copper hydroxide nanobundles precursors grown on copper foam.
[0050] Step 2: Obtain copper nanowires using an electroreduction method:
[0051] Prepare a 1.50 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode, a saturated calomel electrode as the reference electrode, and a copper foam with copper hydroxide nanobundles grown in step 1, clamped with a platinum electrode clamp, as the working electrode. The reduction current density is -30 mA / cm². -2 Electroreduction was performed at room temperature for 30 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 50°C to obtain a copper nanowire array grown on the copper foam.
[0052] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0053] A solution containing 0.05 M nickel sulfate hexahydrate, 0.05 M sodium molybdate dihydrate, 0.50 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 800 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in a vacuum drying oven at 65 °C to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0054] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0055] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0056] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0057] Copper foam was immersed in 2.00 M hydrochloric acid for 20 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried at room temperature. Next, the hydrochloric acid-treated copper foam was immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed at room temperature, and after 25 minutes, the copper foam was turned over with tweezers and immersed for another 25 minutes. The copper foam was then removed with tweezers and rinsed sequentially with deionized water and ethanol. Finally, the copper foam was dried in an 80°C oven to obtain copper hydroxide nanobundles precursors grown on copper foam.
[0058] Step 2: Obtain copper nanowires using an electroreduction method:
[0059] Prepare a 1.00 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode and a saturated calomel electrode as the reference electrode. Clamp the copper foam with copper hydroxide nanobundles grown in step 1 using a platinum electrode clamp. The reduction current density is -30 mA / cm². -2 Electroreduction was performed at room temperature for 30 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 80°C to obtain a copper nanowire array grown on the copper foam.
[0060] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0061] A solution containing 0.05 M nickel sulfate hexahydrate, 0.01 M sodium molybdate dihydrate, 0.50 M sodium hypophosphite, and 0.05 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 1500 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in an 80°C vacuum drying oven to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0062] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0063] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0064] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0065] Copper foam was immersed in 3.00 M hydrochloric acid for 10 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried at room temperature. Then, the hydrochloric acid-treated copper foam was immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed at room temperature, and after 25 minutes, the copper foam in the solution was turned over with tweezers and immersed for another 25 minutes. The copper foam was then removed with tweezers and rinsed with deionized water and ethanol for 2 minutes each. Finally, the copper foam was dried in a 70°C oven to obtain copper hydroxide nanobundles precursor grown on copper foam.
[0066] Step 2: Obtain copper nanowires using an electroreduction method:
[0067] Prepare a 1.20 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode and a saturated calomel electrode as the reference electrode. Clamp the copper foam with copper hydroxide nanobundles grown in step 1 using a platinum electrode clamp. The reduction current density is -50 mA / cm². -2 Electroreduction was performed at room temperature for 15 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 70°C to obtain a copper nanowire array grown on the copper foam.
[0068] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0069] A solution containing 0.05 M nickel sulfate hexahydrate, 0.01 M sodium molybdate dihydrate, 0.70 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 1800 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in a 50°C vacuum drying oven to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0070] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0071] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0072] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0073] Copper foam was immersed in 1.50 M hydrochloric acid for 25 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried at room temperature. Next, the hydrochloric acid-treated copper foam was immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed in a 60°C oven for 10 minutes, then removed. The copper foam in the solution was turned over with tweezers, and the beaker was placed back in the 60°C oven. After another 10 minutes, the beaker was removed again, the copper foam was removed with tweezers, and rinsed sequentially with deionized water and ethanol. Finally, the copper foam was dried in a 70°C oven to obtain a copper hydroxide nanobundle precursor grown on copper foam.
[0074] Step 2: Obtain copper nanowires using an electroreduction method:
[0075] Prepare a 0.90 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode clamp to hold the copper foam with copper hydroxide nanobundles grown in step 1 as the working electrode. The reduction current density is -10 mA / cm². -2 Electroreduction was performed at room temperature for 60 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60°C to obtain a copper nanowire array grown on the copper foam.
[0076] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0077] A solution containing 0.12 M nickel sulfate hexahydrate, 0.09 M sodium molybdate dihydrate, 0.90 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred for 10 minutes as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 500 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol for 2 minutes, and then dried in a vacuum drying oven at 50 °C to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0078] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to the example shown
[0079] As a preferred embodiment of the present invention, a method for preparing a copper@molybdenum modified nickel phosphate nanorod array includes the following steps:
[0080] Step 1: Prepare copper hydroxide nanobundles using the impregnation method:
[0081] Copper foam was immersed in 2.50 M hydrochloric acid for 15 minutes, then rinsed with deionized water and ethanol. The rinsed copper foam was dried in a 60°C oven. Next, the hydrochloric acid-treated copper foam was immersed in a solution containing ammonium persulfate and sodium hydroxide. The beaker was placed at room temperature, and after 25 minutes, the copper foam was turned over with tweezers and immersed for another 25 minutes. The copper foam was then removed with tweezers and rinsed sequentially with deionized water and ethanol. Finally, the copper foam was dried at room temperature to obtain copper hydroxide nanobundles precursors grown on copper foam.
[0082] Step 2: Obtain copper nanowires using an electroreduction method:
[0083] Prepare a 1.50 M sodium sulfate solution and stir for 15 minutes as the electrolyte. Use a graphite rod as the counter electrode, a saturated calomel electrode as the reference electrode, and a copper foam with copper hydroxide nanobundles grown in step 1, clamped with a platinum electrode clamp, as the working electrode. The reduction current density is -30 mA / cm². -2 Electroreduction was performed at room temperature for 40 minutes. Then, the copper foam was removed with tweezers, rinsed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60°C to obtain a copper nanowire array grown on the copper foam.
[0084] Step 3: Obtain copper@molybdenum modified nickel phosphate nanorod arrays using constant voltage electrodeposition method:
[0085] A solution containing 0.10 M nickel sulfate hexahydrate, 0.03 M sodium molybdate dihydrate, 1.20 M sodium hypophosphite, and 0.10 M sodium acetate was prepared and stirred thoroughly to serve as the electrolyte. A graphite rod was used as the counter electrode, a saturated calomel electrode as the reference electrode, and copper foam with grown copper nanowires was used as the working electrode. The electrochemical workstation was set to -1.0 V, and electrodeposition was performed at room temperature for 1000 seconds. After electrodeposition, the copper foam was removed with tweezers, rinsed sequentially with deionized water and ethanol, and then dried in a 65°C vacuum drying oven to obtain a copper@molybdenum modified nickel phosphate nanorod array.
[0086] Step 4: Using a copper@molybdenum-modified nickel phosphate nanorod array as the working electrode, a saturated calomel electrode as the reference electrode, and a graphite rod as the counter electrode, the electrochemical performance of the copper@molybdenum-modified nickel phosphate nanorod array was determined in a three-electrode system. The electrolyte was a 1.00 M phosphate buffer solution. The overpotential of the copper@molybdenum-modified nickel phosphate nanorod array at different current densities was measured. Figure 7 Similar to what is shown.
[0087] Depend on Figure 2It can be seen that the surface of the copper foam is smooth, and a dense and uniform array of nanobundles grows on the copper foam substrate; the diameter of the copper nanowires is significantly smaller than that of the copper hydroxide nanobundles, and the surface is rough, which is due to the removal of hydroxide ions.
[0088] Depend on Figure 3 (a-c) shows a uniform array of nanorods covering the surface of copper foam. The diameter of the deposited nanorods is approximately 600 nm, which is significantly larger than that of copper nanowires. (d) shows the morphology of the molybdenum-modified nickel phosphate nanorods supported on copper nanowires. (e) shows nickel phosphate (-112), molybdenum dioxide (210), and nickel (111) lattice fringes, indicating that molybdenum exists on the catalyst surface in the form of molybdenum dioxide. During electrodeposition, some nickel ions gain electrons to generate nickel nanoparticles. Related literature reports that nickel nanoparticles can promote the dissociation of adsorbed water during the hydrogen evolution reaction, thereby improving the hydrogen evolution performance of the electrocatalyst. HRTEM also shows a large number of amorphous regions on the surface of the electrocatalyst, indicating that the nickel-molybdenum-phosphorus material is a structure in which amorphous and crystalline phases coexist. (f-k) are HAADF-STEM images and corresponding EDX elemental distribution images of Ni-Mo-P / Cu / CF, showing that nickel, molybdenum, phosphorus, and oxygen elements are uniformly distributed on the nanorods, and obvious nickel nanoparticles exist on the surface of the nanorods.
[0089] Depend on Figure 4As shown in (a), for Ni-Mo-P / Cu / CF, the peaks at 873.81 and 856.51 eV represent divalent nickel, attributed to the nickel-oxygen bond in nickel phosphate; the peaks at 234.68 and 231.58 eV represent zero-valent nickel; and the two broad peaks at 879.32 and 861.32 eV are nickel satellite peaks. Compared to Ni-P / Cu / CF, the nickel-oxygen and nickel-nickel peaks in Ni-Mo-P / Cu / CF show slight positive and negative shifts, indicating that the incorporation of molybdenum alters the electronic structure of nickel. In (b), the peaks at 235.41 and 232.31 eV represent hexavalent molybdenum, attributed to the molybdenum-oxygen bond in unreduced molybdate; and the peaks at 234.85 and 231.74 eV represent tetravalent molybdenum, originating from molybdenum dioxide formed after the reduction of molybdate. (c) shows a distinct broad peak, which can be attributed to the presence of phosphorus-oxygen compounds in the phosphate, while the small peak at 130.32 eV can be attributed to the formation of nickel / molybdenum-phosphorus bonds in the phosphide. (d) shows that the Ni-Mo-P XRD spectrum exhibits distinct broad peaks, demonstrating the amorphous nature of Ni-Mo-P. The distinct broad peaks on the spectrum correspond well to nickel phosphate (PDF#38-1473), molybdenum dioxide (PDF#32-0671), and nickel (PDF#45-1027). Therefore, the combined characteristics from SEM, TEM, XPS, and XRD indicate the successful synthesis of a copper@molybdenum modified nickel phosphate nanorod array electrocatalyst.
[0090] Figure 5 and Figure 6 The results are from electrochemical performance tests in a neutral electrolyte (i.e., 1.00 M phosphate buffer solution). Figure 5 Figures (a) and (b) show the hydrogen evolution polarization curves and overpotential comparisons at corresponding current densities for Cu / CF, Ni-Mo-P / CF, Ni-Mo-P / Cu / CF, Ni-P / Cu / CF, and Pt / C / CF. Compared with the control sample, Ni-Mo-P / Cu / CF shows significantly improved performance at current densities of 10 and 100 mA cm⁻¹. -2 At that time, the required overpotentials are 35 and 195 mV. Figure 5 (c) This shows that Ni-Mo-P / Cu / CF has the lowest Tafel slope, indicating a faster hydrogen evolution reaction kinetics. Figure 5 (d) It can be seen that the double layer capacitance of Ni-Mo-P / Cu / CF is the highest and significantly higher than that of Ni-Mo-P / CF. This indicates that the regulation of the copper nanorod structure significantly increases the active reaction area of the electrocatalyst and the number of active centers, thereby improving the electrocatalytic hydrogen evolution performance.
[0091] Depend on Figure 6As shown in (a), Ni-Mo-P / Cu / CF exhibits a smaller charge transfer resistance, indicating that the introduction of molybdenum and the regulation of the nanorod array improve the conductivity of the catalyst, promoting more efficient electron transfer and faster catalytic kinetics, thereby accelerating the hydrogen evolution reaction. (b) shows the reaction of Ni-Mo-P / CF and Ni-Mo-P / Cu / CF in a neutral electrolyte at a charge transfer resistance of 10 mA / cm². -2 Stability tests conducted using current density show that the stability of the catalyst is effectively improved after the nanorod structure is regulated.
[0092] Figure 7 This is a comparison of the electrocatalytic performance of the electrodes of Examples 1-7 under neutral electrolyte conditions. Compared with the samples in Examples 2-7 under other different preparation conditions, Ni-Mo-P / Cu / CF showed the best performance in Example 1, representing the optimal preparation condition.
[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a copper@molybdenum modified nickel phosphate nanorod array, characterized in that, The invention includes a copper@molybdenum modified nickel phosphate nanorod array, wherein the substrate of the copper@molybdenum modified nickel phosphate nanorod array is copper foam, the surface of the copper foam is subjected to nanostructuring treatment, and the copper@molybdenum modified nickel phosphate nanorod array is deposited on the nanostructuring copper foam surface. The preparation method of the copper@molybdenum modified nickel phosphate nanorod array includes the following steps: Step 1: A copper hydroxide nanobundle array was prepared by impregnation of copper foam. After washing and drying the prepared copper hydroxide nanobundles / copper foam with deionized water, it was used as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode. The current density was -10 to -50 mA / cm² in a 0.50–1.50 M sodium sulfate solution. 2 Copper hydroxide nanobundles / copper foam were electro-reduced at room temperature for 20–60 minutes, then washed with deionized water and dried to prepare copper nanowires / copper foam. Step 2: Using copper nanowires / copper foam as the working electrode, graphite rods as the counter electrode, and saturated calomel electrodes as the reference electrode, a solution containing sodium hypophosphite, molybdate ions, divalent nickel ions, and a complexing agent was used as the electrolyte. Nickel-molybdenum-phosphorus material was electrodeposited at a constant voltage of -0.8 to -1.2 V for 500 to 2000 seconds. Afterward, the sample was washed and dried with deionized water and ethanol to prepare a copper@molybdenum modified nickel phosphate nanorod array.
2. The method for preparing copper@molybdenum modified nickel phosphate nanorod arrays according to claim 1, characterized in that, In step 2, the electrolyte is an aqueous solution containing sodium hypophosphite, molybdate, divalent nickel salt and metal complexing agent at different concentrations.
3. The method for preparing copper@molybdenum modified nickel phosphate nanorod arrays according to claim 2, characterized in that, In step 2, the concentrations of sodium hypophosphite, molybdate, divalent nickel salt, and metal complexing agent are 0.50–1.50 M, 0.01–0.10 M, 0.03–0.20 M, and 0.05–0.20 M, respectively.
4. The method for preparing copper@molybdenum modified nickel phosphate nanorod arrays according to claim 1, characterized in that, The diameter of the nanorods in the copper@molybdenum modified nickel phosphate nanorod array is 300–900 nm.
5. The application of a copper@molybdenum modified nickel phosphate nanorod array prepared by the method described in any one of claims 1-4 in the electrolytic desorption of hydrogen in neutral solution, characterized in that, The specific steps of the application are as follows: Electrocatalytic hydrogen evolution reaction was carried out in a neutral three-electrode system using a copper@molybdenum modified nickel phosphate nanorod array as the working electrode.