A method for optimizing hydrogen evolution performance of Raney nickel electrode in alkaline electrolyzer

Abstract

The present invention discloses a method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell. The method for optimizing the hydrogen evolution performance of the present invention comprises: selecting a three-electrode electrochemical system consisting of a platinum counter electrode, a Raney nickel working electrode, a reference electrode and a sulfuric acid electrolyte, scanning the three-electrode electrochemical system by cyclic voltammetry, and first oxidizing and then reducing the platinum on the platinum-based counter electrode to deposit nanoparticles on the surface of the Raney nickel. The method for optimizing the hydrogen evolution performance of the present invention has a simple process, low cost, no environmental pollution, and high atomic utilization, further optimizes the performance of the Raney nickel, reduces the energy consumption of hydrogen production, and achieves cost reduction and efficiency improvement of green hydrogen.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical synthesis and hydrogen production, in particular to a method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell. Background Art

[0002] Water electrolysis technology is a process that uses electricity to decompose water into hydrogen and oxygen (2H2O→2H2+O2). Currently, alkaline water electrolysis (ALK) has attracted widespread attention due to its high technical maturity and low cost. However, the energy consumption of ALK hydrogen production has remained high. 3 Hydrogen requires about 4.5kWh, which greatly increases the electricity cost of hydrogen production. In order to further achieve cost reduction and efficiency improvement of ALK technology and optimize the volume of alkali tank, the development of efficient, fast and low-cost hydrogen evolution catalyst is the key technology.

[0003] At present, commercial Raney nickel is usually used as a hydrogen evolution electrode in industrial ALK hydrogen production electrolyzers. However, the current density of Raney nickel can usually only reach a few hundred milliamperes, so its performance still has room for further modification and improvement. For example, Chinese patent CN116695162A discloses that after a 24-hour erosion pore-forming treatment with an etchant solution, NiCo alloy is applied to the electrode to increase the current density of Raney nickel electrolysis. Chinese patent CN114318361A discloses a method for preparing a vanadium oxide particle-modified electrode on the surface of a Raney nickel alloy electrode by ultrasonic pyrolysis, which reduces the overpotential and increases the current density. Chinese patent CN113430535A uses graphene oxide (GO) as a raw material to construct a multi-metal substrate of NiCoGO through dissolution, composite deposition, tubular furnace incorporation of nitrogen source, argon reduction, multiple ethanol cleaning, cyclic voltammetry and other steps, but does not give a specific optimized hydrogen evolution performance. However, the preparation process and process equipment used in the above method are complex, and at the same time indirectly increase the manpower and equipment costs. Summary of the invention

[0004] In order to optimize the hydrogen evolution performance of Raney nickel efficiently and at low cost, the present invention provides a method for rapidly modifying the Raney nickel electrode with nanoparticles by using electrochemical cyclic voltammetry. The method only requires that in an electrochemical three-electrode system, the platinum atoms of the counter electrode are first oxidized and then reduced to deposit nanoparticles on the Raney nickel working electrode by electrochemical oxidation-reduction, so as to rapidly optimize the hydrogen evolution performance of Raney nickel.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell, which selects a three-electrode electrochemical system consisting of a platinum counter electrode, a Raney nickel working electrode, a reference electrode and a sulfuric acid electrolyte, performs cyclic voltammetry scanning on the three-electrode electrochemical system, and first oxidizes and then reduces the platinum on the platinum counter electrode to deposit nanoparticles on the surface of the Raney nickel.

[0006] The present invention realizes the deposition of Pt nanoparticles by simple electrochemical oxidation-reduction. The Pt counter electrode first loses electrons at an oxidation potential and becomes Pt 2+ (Pt – 2e - → Pt 2+ ), trace amounts of Pt 2+ After dissolving in the solution, it is reduced to the working electrode and becomes Pt 0 (Pt 2+ +2e - → Pt 0 ) is deposited on Raney nickel.

[0007] The parameter settings of cyclic voltammetry, including scan rate, voltage range, and number of times, will greatly affect the Pt deposition rate, nucleation mechanism, nucleation size, and catalytic size effect.

[0008] Furthermore, the scanning number of the cyclic voltammetry is 250-350 times, preferably 280-320 times, and most preferably 300 times. Too low scanning number will result in insufficient Pt atoms loaded on the Raney nickel electrode, resulting in poor hydrogen evolution performance; too high scanning number will cause Pt atoms to agglomerate into large particles rather than nanoparticles, thereby losing the size effect, weakening the hydrogen evolution performance, and also causing easy shedding.

[0009] Furthermore, the scanning interval of the cyclic voltammetry is 0.0V~-0.5V.

[0010] Furthermore, the scanning rate of the cyclic voltammetry is 100-200 mV / s, preferably 100-150 mV / s, and most preferably 100 V / s. Too fast a scanning rate will lead to faster nucleation of Pt and failure to disperse and nucleate with nanoparticles, while too slow a scanning rate will increase the reaction time.

[0011] The present invention has a significant effect on improving the synthesis rate and reducing the material and electricity costs by reasonably setting the parameters of the cyclic voltammetry, such as the voltage range, the scanning speed and the number of times.

[0012] Furthermore, the material of the platinum counter electrode is one of a platinum sheet, a platinum mesh, and a platinum wire, which can provide a large amount of Pt atoms.

[0013] Furthermore, the reference electrode is an Ag / AgCl electrode.

[0014] Furthermore, the Raney nickel working electrode is a commercial Raney nickel electrode, which reduces labor costs and does not require cumbersome material synthesis steps such as pretreatment, high-temperature calcination, complex chemicals involved in the reaction, and post-treatment.

[0015] Furthermore, the sulfuric acid is preferably 0.4-0.6M H2SO4.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The nanoparticle Pt atoms dispersed on the Raney nickel, on the one hand, greatly increase the number of active sites, and on the other hand, optimize the hydrogen evolution reaction kinetics of the Raney nickel electrode; in addition, the deposition method of the nanoparticles also further greatly improves the utilization rate of the metal Pt atoms. 2. The present invention only uses commercial low-cost Raney nickel as the working electrode, without the tedious material synthesis steps of pretreatment, high-temperature calcination, complex drugs participating in the reaction, post-treatment, etc. The modification of the Raney nickel electrode can be achieved only through a short period of cyclic voltammetry oxidation-reduction, which is suitable for large-scale industrial production. 3. Compared with the performance of ordinary untreated Raney nickel electrode mesh, the performance of the present invention is improved by 4-5 times, and the effect is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the principle diagram of the electrochemical oxidation of the present invention;

[0018] Figure 2 A diagram of an electrochemical device of the present invention;

[0019] Figure 3 The HER performance diagram after cyclic voltammetry using Pt as the counter electrode;

[0020] Figure 4 This is the original Raney nickel SEM image before cyclic voltammetry scanning;

[0021] Figure 5 This is the SEM image of Raney nickel after cyclic voltammetry scanning 300 times;

[0022] Figure 6 This is the HER performance diagram tested after cyclic voltammetry using a graphite rod electrode as the counter electrode. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be described clearly and completely below in conjunction with the drawings of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example

[0025] This embodiment provides a method for optimizing the hydrogen evolution performance of Raney nickel by electrochemical method with high efficiency and low cost. Figure 1 As shown, the Raney nickel electrode is modified in situ by oxidizing and reducing a trace amount of Pt on a platinum sheet electrode, which includes the following steps:

[0026] Step 1: Figure 2The three-electrode system was constructed as shown: Pt sheet (1*1cm), Ag / AgCl electrode, and commercial Raney nickel electrode (1*1.2cm) were used as counter electrode, reference electrode, and working electrode, respectively. 20℃, 0.5M H2SO4 was used as the electrolyte.

[0027] Step 2: Cyclic voltammetry for redox deposition. Commercial Raney nickel was used as the working electrode and an electrochemical workstation was used in a three-electrode electrochemical system at a voltage range of 0.0 V to -0.5 V. vs RHE, scan rate was 100 mV / s, and cyclic voltammetry (CV) was performed for different times, including 100 times (circle) and 300 times.

[0028] Step 3: Test the effect of different cycle times on performance. Based on the Raney nickel electrode after CV scanning as the working electrode, the Pt sheet as the counter electrode, and 1.0 M KOH as the electrolyte, a three-electrode test was performed using an electrochemical workstation in the voltage range of 0.0V~-0.4V vs . RHE, the change of hydrogen evolution performance at different CV scan numbers was evaluated by linear sweep voltammetry (LSV) at a scan rate of 100 mV / s.

[0029] like Figure 3 As shown in the figure, in the system with Pt-based electrode as the counter electrode, the HER hydrogen evolution performance is significantly improved under the action of CV scanning. The LSV results show that the hydrogen evolution current density increases significantly with the increase in the number of scans. The Raney nickel hydrogen evolution response current density after 100 CV cycle scans is about 2 times the performance of the original Raney nickel electrode. The Raney nickel hydrogen evolution response current density after 300 CV cycle scans is 4.5 times the performance of the original Raney nickel electrode. At -0.4V vs . ~900 mA cm was achieved at the RHE overpotential -2 This phenomenon shows that the Pt of the counter electrode first dissolves into 2 + After the Pt is removed, it is reduced to 0 valence and deposited on the surface of Raney nickel, achieving nanoscale optimization of Raney nickel and thus improving the hydrogen evolution performance of Raney nickel.

[0030] The surface morphology of the original Raney nickel and the Raney nickel after cyclic voltammetry scanning were further compared by SEM characterization. The experimental results show that the original Raney nickel has a smooth surface (see Figure 4 ), however, after CV treatment, the surface of Raney nickel becomes rough (see Figure 5 ), and the surface is uniformly enriched with Pt nanoparticles, indicating that the selection of the CV parameters can achieve rapid and uniform deposition of Pt nanoparticles, thereby optimizing the HER performance of Raney nickel.

[0031] Comparative Example

[0032] Step 1: Figure 2 A three-electrode system was constructed as shown, with graphite sheet (1*1cm), Ag / AgCl electrode, and commercial Raney nickel electrode (1*1.5cm) as counter electrode, reference electrode, and working electrode, respectively. 20℃, 0.5 M H2SO4 was used as the electrolyte.

[0033] Step 2: Redox deposition by cyclic voltammetry. Commercial Raney nickel was used as the working electrode and an electrochemical workstation was used in a three-electrode system with a voltage range of 0.0 V to -0.5 V. vs RHE, scan rate was 100 mV / s, and different numbers of CV scans were performed, including 100 and 300 times.

[0034] Step 3: Test the effect of different cycle times on performance. Using the Raney nickel electrode after CV scanning as the working electrode and the stone grinding rod electrode as the counter electrode, a three-electrode test was performed using an electrochemical workstation in the voltage range of 0.0V-0.4V. vs . RHE, 1.0 M KOH as electrolyte, the changes of HER at different CV scan numbers were evaluated by linear sweep voltammetry (LSV).

[0035] like Figure 6 As shown, in the electrochemical system with the stone mill rod electrode as the counter electrode, the HER hydrogen evolution performance of the Raney nickel electrode treated by cyclic voltammetry does not have a significant performance improvement under the action of CV, but the response current density is greatly attenuated. The comparison between this comparative example and the embodiment further verifies that the Pt counter electrode is deposited on the surface of the Raney nickel as nanoparticles under the action of redox, thereby optimizing the hydrogen evolution performance of the Raney nickel.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell, characterized in that: A three-electrode electrochemical system consisting of a platinum counter electrode, a Raney nickel working electrode, a reference electrode and a sulfuric acid electrolyte was selected, and a cyclic voltammetry scan was performed on the three-electrode electrochemical system, and the platinum on the platinum counter electrode was first oxidized and then reduced to deposit nanoparticles on the surface of the Raney nickel.

2. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 1, characterized in that: The scanning number of the cyclic voltammetry is 250-350 times.

3. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 2, characterized in that: The scanning number of the cyclic voltammetry is 280-320 times.

4. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 2, characterized in that: The scanning interval of the cyclic voltammetry is 0.0V~-0.5V.

5. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 2, characterized in that: The scanning rate of the cyclic voltammetry is 100-200 mV / s.

6. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 5, characterized in that: The scanning rate of the cyclic voltammetry is 100-150 mV / s.

7. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 1, characterized in that: The material of the platinum counter electrode is one of a platinum sheet, a platinum mesh and a platinum wire.

8. The method for optimizing hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 1, characterized in that: The reference electrode is an Ag / AgCl electrode.

9. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 1, characterized in that: The Raney nickel working electrode is a commercial Raney nickel electrode.

10. The method for optimizing the hydrogen evolution performance of a Raney nickel electrode in an alkaline electrolytic cell according to claim 1, characterized in that: The sulfuric acid is 0.4-0.6M H2SO4.

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