A method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on phase-selective corrosion mechanism

Abstract

A method for preparing a rare-earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism is disclosed, belonging to the field of water electrolysis catalyst technology. This invention addresses the problems of traditional chemical corrosion methods, such as the simultaneous loss of active sites during corrosion, the inability to simultaneously meet the requirements of pore formation and activity retention, the lack of precise control, and the generation of large amounts of acidic wastewater containing heavy metals. The method comprises: 1. Preparation of a rare-earth-doped NiCoMnIn alloy substrate; 2. Pretreatment; 3. Electrochemical corrosion. This invention is used for the preparation of a rare-earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis catalyst technology. Background Technology

[0002] Current research on hydrogen evolution reaction (HER) catalysts mainly focuses on nanostructured materials, including nanoparticles, nanowires, two-dimensional nanosheets, and various composite heterostructures. While these materials exhibit high intrinsic activity under laboratory conditions, they generally suffer from poor long-term stability, interfacial resistance introduced by binders, and insufficient consistency in batch production, resulting in high barriers to industrialization. In contrast, bulk multi-element alloy electrodes, prepared by vacuum melting, are self-supporting monolithic structures that do not require binders. Compositional uniformity and batch consistency are ensured by metallurgical processes, and they exhibit superior chemical stability under harsh conditions of strong acid electrolytes and high current densities, possessing engineering advantages not found in nanostructured catalysts. However, the active sites of dense alloys are almost entirely concentrated on the geometric surface, completely sealing the internal active components. The ratio of electrochemical active surface area (ECSA) to geometric area is typically only 3–8, leading to limited mass transfer, severe bubble coverage, and rapid overpotential increases at industrial-grade current densities. How to overcome the inherent limitations of specific surface area while retaining all the engineering advantages of bulk alloys is the core challenge that urgently needs to be addressed in this field.

[0003] Against this backdrop, dealloying pore-forming strategies have been widely used to improve the effective specific surface area of ​​multi-component alloys. However, traditional chemical corrosion methods have three fundamental drawbacks: most multi-component alloy systems are dominated by solid solutions, with each component uniformly distributed in the same lattice, resulting in limited differences in corrosion resistance between phases; active sites are simultaneously lost during corrosion, making it impossible to simultaneously meet the needs of pore formation and retention. Furthermore, traditional strong acid chemical corrosion cannot be precisely controlled, and the generation of large amounts of acidic wastewater containing heavy metals also brings serious environmental compliance pressures, hindering large-scale clean production. Summary of the Invention

[0004] This invention aims to address the problems of simultaneous loss of active sites during the corrosion process in traditional chemical etching methods, which cannot simultaneously meet the requirements of pore formation and retention, lack precise control, and generate a large amount of acidic waste liquid containing heavy metals. Therefore, it provides a method for preparing rare earth-doped NiCoMnIn alloy hydrogen evolution electrodes based on phase-selective corrosion mechanism.

[0005] A method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism, comprising the following steps:

[0006] I. According to the general chemical formula (NiCoMnIn) 100-x RE xThe raw materials were weighed according to the atomic ratio, and rare earth-doped NiCoMnIn alloy ingots were prepared by vacuum melting. Then, they were processed into alloy substrates to obtain rare earth-doped NiCoMnIn alloy substrates.

[0007] The RE is one or a combination of several of La, Ce, Pr, Nd, Sm and Gd; x = 0.1~3;

[0008] 2. The rare earth-doped NiCoMnIn alloy substrate is subjected to mechanical grinding, ultrasonic cleaning and acid pickling activation in sequence to obtain the pretreated alloy substrate.

[0009] 3. Using the pretreated alloy substrate as the working electrode, a platinum sheet or carbon rod as the counter electrode, and mercurous sulfate as the reference electrode, electrochemical corrosion is carried out in an acidic electrolyte to form a connected nanoporous structure. Finally, the electrode is washed and dried to obtain a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism.

[0010] The beneficial effects of this invention are:

[0011] 1. This invention is the first to introduce NiCoMnIn alloys with equal atomic ratios into the field of hydrogen evolution through water electrolysis. Utilizing the natural difference in corrosion resistance between the easily corroded and corrosion-resistant phases in the as-cast microstructure of this system, selective corrosion pore formation is achieved. Under acidic electrochemical corrosion conditions, the elemental Co phase exhibits different corrosion resistance compared to the NiMnIn and NiIn phases. The elemental Co phase is dissolved through dealloying, forming a connected porous network, while the Ni-based intermetallic compound phase is retained to form an active framework. Active sites are fully exposed, and pore formation and retention are naturally unified in the same electrochemical process. This fundamentally solves the inherent contradiction of uncontrollable loss of active components in existing dealloying pore formation strategies. The electrochemically active area (ECSA) of the prepared electrode is significantly increased compared to dense alloy substrates, and its mass transfer performance at industrial-grade current densities is significantly superior to that of dense bulk electrodes.

[0012] 2. Ce doping significantly enhances the intrinsic HER activity of the dealloyed electrode: At the same current density (10 mA / cm²), the overpotential of the Ce-doped sample is significantly lower than that of the undoped control electrode, and the Tafel slope is reduced. This indicates that the introduction of Ce not only expands the electrochemical active area but also effectively improves the intrinsic switching frequency per unit active site. This performance improvement stems from the segregation regulation of Ce at the NiMnIn / NiIn phase interface after dealloying: the enrichment of Ce at the interface optimizes the adsorption free energy of the hydrogen intermediate at the Ni active site, reducing the activation energy of the rate-determining step of HER, thereby achieving a significant enhancement of catalytic activity without sacrificing structural stability.

[0013] 3. Electrochemical corrosion uses acidic solution as the medium and replaces uncontrollable strong acid immersion with programmable potential waveform. The pore structure can be quantitatively controlled by adjusting the potential amplitude, sweep rate and corrosion time. It has good repeatability, the corrosion medium can be recycled, and there is no need to treat a large amount of strong acid waste liquid containing heavy metals, which meets the requirements of green manufacturing.

[0014] 4. This invention fully retains the engineering advantages of block alloys, such as self-support, no need for binders, high mechanical stability, and good batch consistency. The prepared electrodes have no risk of active layer detachment and can operate stably for a long time under harsh conditions of industrial electrolytes and high current density, with low barriers to industrial transformation. Attached Figure Description

[0015] Figure 1 The images show the SEM microstructure comparison of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrodes prepared in Examples 1 to 5 before and after electrochemical etching to create pores. (a) is the alloy substrate after pretreatment in step 2 of Example 1; (b) is the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1; (c) is the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 2; (d) is the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 3; (e) is the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 4; and (f) is the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 5.

[0016] Figure 2 The figures show the comprehensive electrochemical performance characterization of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1 and the NiCoMnIn alloy hydrogen evolution electrode prepared in the comparative experiment before and after corrosion pore formation. (a) shows the performance at 10 mA / cm². 2 The lower double-layer capacitance (Cdl) test curve, (b) is at 10mA / cm 2 The LSV polarization curves are shown in (c) at 10 mA / cm. 2 and 50mA / cm 2 Overpotential bar chart comparison, (d) is at 10 mA / cm 2 Below is the EIS Nyquist plot, (e) is at 10 mA / cm 2 Tafel slope fitting results;

[0017] Figure 3 For 10mA / cm 2 Below is a chronocurrent stability test result of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1.

[0018] Figure 4 The XRD patterns of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1 before and after corrosion and pore formation are shown. Detailed Implementation

[0019] Specific Implementation Method 1: This implementation method is a method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism, which is carried out according to the following steps:

[0020] I. According to the general chemical formula (NiCoMnIn) 100-x RE x The raw materials were weighed according to the atomic ratio, and rare earth-doped NiCoMnIn alloy ingots were prepared by vacuum melting. Then, they were processed into alloy substrates to obtain rare earth-doped NiCoMnIn alloy substrates.

[0021] The RE is one or a combination of several of La, Ce, Pr, Nd, Sm and Gd; x = 0.1~3;

[0022] 2. The rare earth-doped NiCoMnIn alloy substrate is subjected to mechanical grinding, ultrasonic cleaning and acid pickling activation in sequence to obtain the pretreated alloy substrate.

[0023] 3. Using the pretreated alloy substrate as the working electrode, a platinum sheet or carbon rod as the counter electrode, and mercurous sulfate as the reference electrode, electrochemical corrosion is carried out in an acidic electrolyte to form a connected nanoporous structure. Finally, the electrode is washed and dried to obtain a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism.

[0024] Principle: If a multiphase coexistence structure with significantly different corrosion resistance can spontaneously form in the as-cast microstructure of an alloy system, allowing the easily corroded phase and the corrosion-resistant phase to naturally separate, the easily corroded phase, due to its low bonding energy, will preferentially dissolve and form pores, while the corrosion-resistant phase, due to its ordered structure and high bonding energy, will be retained to form an active framework. Pore formation and retention can then be naturally unified in the same electrochemical process. This phase-selective corrosion mechanism fundamentally eliminates the inherent contradiction of uncontrollable loss of active components in existing dealloying pore-forming strategies. This specific implementation addresses the technical bottleneck of the lack of phase selectivity and uncontrollable loss of active components in existing dealloying pore-forming strategies by providing a method for preparing a rare-earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism. The NiCoMnIn alloy system with equal atomic ratios simultaneously contains both easily corroded and corrosion-resistant phases; the natural difference in corrosion resistance between the two phases provides a driving force for phase-selective corrosion, which is beneficial for forming a porous structure. Under acidic electrochemical corrosion conditions, the elemental Co phase, as the easily corroded phase, dissolves first, while the intermetallic compound phases formed by Ni with Mn and In, which have high bonding energies, remain to constitute the active framework, exposing a large number of active sites. Therefore, the electrode specific surface area is significantly increased while completely preserving the Ni-based intermetallic compound active framework, forming a connected nanoporous structure on the alloy surface and subsurface. More importantly, the NiMnIn / NiIn two-phase interface formed in the framework after dealloying is the core site that determines the intrinsic HER activity. Ce, as a rare earth element, has a unique 4f electron configuration and a large atomic radius, and will preferentially segregate at the NiMnIn / NiIn phase interface during solidification and subsequent corrosion. By controlling the interface electronic structure and optimizing the hydrogen adsorption free energy, the intrinsic HER activity of the interface active sites is significantly improved, reaching 10 mA / cm². 2 The overpotential at current density is significantly lower than that of the undoped Ce sample.

[0025] The beneficial effects of this embodiment are:

[0026] 1. This embodiment introduces NiCoMnIn alloys with equal atomic ratios into the field of hydrogen evolution through water electrolysis for the first time. Utilizing the natural difference in corrosion resistance between the easily corroded and corrosion-resistant phases in the as-cast microstructure of this system, selective corrosion pore formation is achieved. Under acidic electrochemical corrosion conditions, the elemental Co phase exhibits different corrosion resistance compared to the NiMnIn and NiIn phases. The elemental Co phase dissolves through dealloying, forming a connected porous network, while the Ni-based intermetallic compound phase is retained to form an active framework. Active sites are fully exposed, and pore formation and retention are naturally unified in the same electrochemical process. This fundamentally solves the inherent contradiction of uncontrollable loss of active components in existing dealloying pore formation strategies. The electrochemically active area (ECSA) of the prepared electrode is significantly increased compared to dense alloy substrates, and its mass transfer performance at industrial-grade current densities is significantly superior to that of dense bulk electrodes.

[0027] 2. Ce doping significantly enhances the intrinsic HER activity of the dealloyed electrode: At the same current density (10 mA / cm²), the overpotential of the Ce-doped sample is significantly lower than that of the undoped control electrode, and the Tafel slope is reduced. This indicates that the introduction of Ce not only expands the electrochemical active area but also effectively improves the intrinsic switching frequency per unit active site. This performance improvement stems from the segregation regulation of Ce at the NiMnIn / NiIn phase interface after dealloying: the enrichment of Ce at the interface optimizes the adsorption free energy of the hydrogen intermediate at the Ni active site, reducing the activation energy of the rate-determining step of HER, thereby achieving a significant enhancement of catalytic activity without sacrificing structural stability.

[0028] 3. Electrochemical corrosion uses acidic solution as the medium and replaces uncontrollable strong acid immersion with programmable potential waveform. The pore structure can be quantitatively controlled by adjusting the potential amplitude, sweep rate and corrosion time. It has good repeatability, the corrosion medium can be recycled, and there is no need to treat a large amount of strong acid waste liquid containing heavy metals, which meets the requirements of green manufacturing.

[0029] 4. This implementation method fully retains the engineering advantages of block alloys, such as self-support, no need for binders, high mechanical stability, and good batch consistency. The prepared electrodes have no risk of active layer detachment and can operate stably for a long time under harsh conditions of industrial electrolyte and high current density, with low barriers to industrial transformation.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the raw materials mentioned in step one are Ni blocks, Co blocks, Mn blocks, In blocks, and rare earth element blocks, and the purity of the raw materials is ≥99.9%. Everything else is the same as in Specific Implementation Method One.

[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the vacuum melting method described in step one is vacuum arc melting or vacuum induction melting; specifically, the vacuum arc melting is carried out in an argon atmosphere with a vacuum degree ≤5×10⁻⁶. -3 Under conditions of Pa and current input of 100A~500A, smelting is carried out for 1h~1.5h. Other procedures are the same as in specific implementation method one or two.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the smelting process involves turning and remelting the material ≥ 5 times. Everything else is the same as Specific Implementation Methods One to Three.

[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the thickness of the rare earth-doped NiCoMnIn alloy substrate mentioned in step one is 1mm to 3mm. Everything else is the same as in Specific Implementation Methods One to Four.

[0034] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in the following ways: The mechanical polishing described in step two involves sequentially polishing the surface with 400#, 800#, 1200#, and 2000# sandpaper until no obvious scratches are visible. The ultrasonic cleaning described in step two involves ultrasonically cleaning the surface for 10-15 minutes each in acetone, anhydrous ethanol, and deionized water at room temperature and a power of 60W-100W. The acid washing activation described in step two involves immersing the surface in 0.1mol / L-0.5mol / L dilute hydrochloric acid or 0.1mol / L-0.5mol / L dilute sulfuric acid for 30-120 seconds, followed by rinsing with deionized water. The rest is the same as in Specific Implementation Methods One to Five.

[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the acidic electrolyte mentioned in step three is hydrochloric acid with a concentration of 0.1 mol / L to 1 mol / L or sulfuric acid with a concentration of 0.1 mol / L to 1 mol / L. Everything else is the same as in Specific Implementation Methods One to Six.

[0036] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the potential waveform in the electrochemical corrosion described in step three is one or a combination of several of the following: constant potential, cyclic voltammetry, and square wave pulse. Everything else is the same as in Specific Implementation Methods One to Seven.

[0037] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the electrochemical corrosion described in step three is specifically carried out under the conditions of a potential of -0.5V vs. MSE to +0.5V vs. MSE for 10 to 120 minutes; the washing and drying described in step three is specifically carried out according to the following steps: rinsing ≥3 times each with deionized water and anhydrous ethanol, and then drying at a temperature of 25℃ to 60℃. Everything else is the same as in Specific Implementation Methods One to Eight.

[0038] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step three, the difference in corrosion resistance between the elemental Co phase and the Ni-based intermetallic compound phase allows for the selective dissolution of the elemental Co phase, forming a connected nanoporous structure. Everything else is the same as in Specific Implementation Methods One to Nine.

[0039] The beneficial effects of the present invention are verified using the following embodiments:

[0040] Example 1:

[0041] A method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism, comprising the following steps:

[0042] I. Based on the chemical formula (NiCoMnIn) 99.9 Ce 0.1 Ni, Co, Mn, In, and Ce blocks were weighed as raw materials and placed in a vacuum arc melting furnace under an argon atmosphere and a vacuum degree of 5 × 10⁻⁶. -3 Under the conditions of Pa and current input of 300A, the alloy was smelted for 1 hour, and the alloy was turned over and remelted 5 times during the 1 hour of smelting to obtain rare earth doped NiCoMnIn alloy ingot. The rare earth doped NiCoMnIn alloy ingot was cooled, cut and polished to obtain rare earth doped NiCoMnIn alloy substrate.

[0043] The purity of the raw material is 99.9%; the dimensions of the rare earth-doped NiCoMnIn alloy substrate are 10mm×10mm×2mm.

[0044] 2. The rare earth-doped NiCoMnIn alloy substrate was successively polished with 400#, 800#, 1200#, and 2000# sandpaper until there were no obvious scratches on the surface. Then, under the conditions of room temperature and power of 60W, it was ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 10 minutes each. Then, it was acid-washed with 0.2mol / L dilute hydrochloric acid for 60 seconds. Finally, it was rinsed with deionized water to obtain the pretreated alloy substrate (named Ce-NiCoMnIn).

[0045] 3. Using the pretreated alloy substrate as the working electrode, a platinum sheet as the counter electrode, and mercurous sulfate as the reference electrode, and sulfuric acid with a concentration of 0.5 mol / L as the electrolyte, electrochemical corrosion was carried out for 20 min under a constant potential of -0.2 V vs. MSE. Taking advantage of the difference in corrosion resistance between the Co elemental phase and the Ni-based intermetallic compound phase, the Co elemental phase was selectively dissolved to form a connected nanoporous structure. Finally, the electrode was rinsed three times each with deionized water and anhydrous ethanol, and then dried at a temperature of 50 °C to obtain a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode (named Ce-NiCoMnIn-DE).

[0046] Example 2: This example differs from Example 1 in that a constant potential of -0.3 V vs. MSE is applied in step 3. Everything else is the same as in Example 1.

[0047] Example 3: This example differs from Example 1 in that a constant potential of -0.1 V is applied in step 3 compared to MSE. Everything else is the same as in Example 1.

[0048] Example 4: This example differs from Example 1 in that the etching time in step 3 is 10 minutes. Everything else is the same as in Example 1.

[0049] Example 5: This example differs from Example 1 in that the etching time in step three is 30 minutes. Everything else is the same as in Example 1.

[0050] Comparative experiment: The difference between this embodiment and Embodiment 1 is that the chemical formula in step one is Ni. 25 Co 25 Mn 25 In 25 The atomic ratio of Ni, Co, Mn, and In blocks was used as raw materials; the pretreated alloy substrate obtained in step two was named NiCoMnIn; the NiCoMnIn alloy hydrogen evolution electrode prepared in step three was named NiCoMnIn-DE. Other steps were the same as in Example 1.

[0051] Figure 1 The images show a comparison of the SEM microstructures of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrodes prepared in Examples 1 to 5 before and after electrochemical etching for pore formation. (a) shows the alloy substrate after pretreatment in step two of Example 1; (b) shows the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1; (c) shows the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 2; (d) shows the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 3; (e) shows the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 4; and (f) shows the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 5. As shown in (a), the surface before etching for pore formation is smooth and dense, with only a few grinding scratches and no obvious porous structure. As shown in (b), a large number of uniformly distributed porous structures are formed on the surface of Example 1, with interconnected channels, significantly increasing the specific surface area. This demonstrates the effectiveness of the electrochemical etching pore formation strategy, and the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode of Example 1 is the best sample.

[0052] Figure 2 The figures show the comprehensive electrochemical performance characterization of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1 and the NiCoMnIn alloy hydrogen evolution electrode prepared in the comparative experiment before and after corrosion pore formation. (a) shows the performance at 10 mA / cm². 2 The lower double-layer capacitance (Cdl) test curve, (b) is at 10mA / cm 2 The LSV polarization curves are shown in (c) at 10 mA / cm. 2 and 50mA / cm 2 Overpotential bar chart comparison, (d) is at 10 mA / cm 2 Below is the EIS Nyquist plot, (e) is at 10 mA / cm 2The Tafel slope fitting results are shown in Figure (a). Figure (a) shows the double-layer capacitance (Cdl) test curves for each sample. The Cdl value of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode of Example 1 after Ce doping and etching is 7.1 mF·cm. -2 The values ​​were higher than those of the uncorroded original alloy (1.3 mF·cm). -2 ) and samples under different corrosion conditions (2.2 mF·cm) -2 3.7mF·cm -2 This demonstrates that the ECSA (electrochemical corrosion-induced pore formation) was significantly improved after phase-selective electrochemical etching, and Ce doping further increased the number of effective active sites. Figure (b) shows the LSV polarization curves. The rare earth-doped NiCoMnIn alloy hydrogen evolution electrode of Example 1 after Ce doping and etching-induced pore formation showed a significant improvement at 10 mA / cm². 2 The lowest overpotential and the best HER activity were observed at the lowest current density. Figure (c) shows the results for each sample at 10 mA / cm². 2 and 50mA / cm 2 The overpotential bar chart shows that the Ce-doped and etched NiCoMnIn alloy hydrogen evolution electrode of Example 1 has the lowest overpotential (192 mV and 293 mV), demonstrating a significant and intuitive performance improvement. Figure (d) shows the EIS Nyquist plot, where the Ce-doped and etched NiCoMnIn alloy hydrogen evolution electrode of Example 1 has the lowest charge transfer resistance (Rct) and the highest interfacial charge transport efficiency, consistent with the effect of Ce in optimizing the interfacial electronic structure and reducing the charge transfer barrier at the NiMnIn / NiIn phase interface. Figure (e) shows the Tafel slope fitting results, where the Tafel slope of the Ce-doped and etched NiCoMnIn alloy hydrogen evolution electrode of Example 1 is 117.77 mV·dec. -1 The results were significantly lower than those of the control sample without rare earth doping and without corrosion pore formation, indicating that the introduction of Ce improved the HER reaction kinetics and accelerated the rate-determining step.

[0053] Figure 3 For 10mA / cm 2 Below is a chronocurrent stability test graph of the rare-earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1. As shown in the graph, under constant current testing conditions, the electrode current density remained stable for a long period of 450 hours without significant attenuation, demonstrating that the prepared electrode has good long-term operational stability.

[0054] Figure 4The figures show the XRD patterns of the rare earth-doped NiCoMnIn alloy hydrogen evolution electrode prepared in Example 1 before and after etching and pore formation. As can be seen from the figures, before etching and pore formation, the diffraction peaks match the standard cards for Ni2MnIn (PDF#04-005-7780), NiIn (PDF#04-004-6500), and Co (PDF#04-006-4263), proving that the alloy is mainly composed of the above phases after melting, and that Ce doping did not introduce any obvious impurity phases, maintaining the integrity of the alloy phase structure. After etching and pore formation, the characteristic peaks of the Co element decrease, proving the selective extraction of Co.

Claims

1. A method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism, characterized in that... It is done in the following steps: I. According to the general chemical formula (NiCoMnIn) 100-x RE x The raw materials were weighed according to the atomic ratio, and rare earth-doped NiCoMnIn alloy ingots were prepared by vacuum melting. Then, they were processed into alloy substrates to obtain rare earth-doped NiCoMnIn alloy substrates. The RE is one or a combination of several of La, Ce, Pr, Nd, Sm and Gd; x = 0.1~3; 2. The rare earth-doped NiCoMnIn alloy substrate is subjected to mechanical polishing, ultrasonic cleaning and acid pickling activation in sequence to obtain the pretreated alloy substrate.

3. Using the pretreated alloy substrate as the working electrode, a platinum sheet or carbon rod as the counter electrode, and mercurous sulfate as the reference electrode, electrochemical corrosion is carried out in an acidic electrolyte to form a connected nanoporous structure. Finally, the electrode is washed and dried to obtain a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism.

2. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The raw materials mentioned in step one are Ni blocks, Co blocks, Mn blocks, In blocks and rare earth element blocks, and the quality purity of the raw materials is ≥99.9%.

3. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The vacuum melting method described in step one is vacuum arc melting or vacuum induction melting; specifically, the vacuum arc melting is carried out in an argon atmosphere with a vacuum degree ≤ 5 × 10⁻⁶. -3 Melting time is 1 hour to 1.5 hours under the conditions of Pa and current input of 100A to 500A.

4. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 3, characterized in that... The smelting process involves turning and remelting the material ≥ 5 times.

5. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The thickness of the rare earth-doped NiCoMnIn alloy substrate mentioned in step one is 1mm to 3mm.

6. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The mechanical polishing described in step two specifically involves sequentially polishing the surface with 400#, 800#, 1200#, and 2000# sandpaper until there are no obvious scratches. The ultrasonic cleaning described in step two specifically involves ultrasonically cleaning the surface for 10 to 15 minutes each in acetone, anhydrous ethanol, and deionized water at room temperature and a power of 60W to 100W. The acid pickling activation described in step two specifically involves immersing the surface in 0.1 mol / L to 0.5 mol / L dilute hydrochloric acid or 0.1 mol / L to 0.5 mol / L dilute sulfuric acid for 30 to 120 seconds, followed by rinsing with deionized water.

7. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The acidic electrolyte mentioned in step three is hydrochloric acid with a concentration of 0.1 mol / L to 1 mol / L or sulfuric acid with a concentration of 0.1 mol / L to 1 mol / L.

8. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The potential waveform in the electrochemical corrosion described in step three is one or a combination of several of the following: constant potential, cyclic voltammetry, and square wave pulse.

9. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... The electrochemical corrosion described in step three is specifically carried out under the conditions of potential range of -0.5V vs. MSE to +0.5V vs. MSE for 10 min to 120 min; the washing and drying described in step three is specifically carried out according to the following steps: rinsed ≥3 times each with deionized water and anhydrous ethanol, and then dried at a temperature of 25℃ to 60℃.

10. The method for preparing a rare earth-doped NiCoMnIn alloy hydrogen evolution electrode based on a phase-selective corrosion mechanism according to claim 1, characterized in that... In step three, the difference in corrosion resistance between the elemental Co phase and the Ni-based intermetallic compound phase is utilized to selectively dissolve the elemental Co phase, forming a connected nanoporous structure.

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