阅读说明：本技术 一种Co-Mo-Er2O3镀层及其制备方法与应用 (Co-Mo-Er2O3Coating and preparation method and application thereof ) 是由 马立文 田娅 席晓丽 聂祚仁 于 2021-05-07 设计创作，主要内容包括：本发明涉及电镀技术领域,具体涉及一种Co-Mo-Er-2O-3镀层及其制备方法及应用。本发明提供的Co-Mo-Er-2O-3镀层为非晶态合金涂层,其以Co-Mo合金为主相,以Er-2O-3纳米粒子为掺杂相。本发明通过将稀土材料Er-2O-3以纳米粒子形式掺入Co-Mo合金主相中,可与主相产生协同作用,显著提高Co-Mo镀层的电解水析氢性能。同时,本发明提出采用直流电沉积法制备Co-Mo-Er-2O-3镀层,该方法具有工艺简单、沉积快、镀层致密纯度高、可操作性强、成本低等优点,有望在工业上得到广泛的应用。(The invention relates to the technical field of electroplating, in particular to Co-Mo-Er 2 O 3 A plating layer and a preparation method and application thereof. The invention provides Co-Mo-Er 2 O 3 The coating is an amorphous alloy coating which takes Co-Mo alloy as a main phase and Er 2 O 3 The nanoparticles are the doped phase. The invention is prepared by adding rare earth material Er 2 O 3 The nano particles are doped into the Co-Mo alloy main phase, and can generate synergistic action with the main phase, thereby obviously improving the hydrogen evolution performance of the Co-Mo plating layer by electrolyzing water. Meanwhile, the invention provides a method for preparing Co-Mo-Er by adopting a direct current deposition method 2 O 3 Coating, the method has simple process and depositionFast speed, compact plating layer, high purity, strong operability, low cost and the like, and is expected to be widely applied in industry.)

1. Co-Mo-Er₂O₃The coating is characterized in that Co-Mo alloy is used as a main phase, and Er is used as a main phase₂O₃The nanoparticles are the doped phase.

2. The Co-Mo-Er of claim 1₂O₃A coating layer, wherein said Er₂O₃The doping ratio of the nano particles is Co-Mo-Er₂O₃6-8% of the total mass of the plating layer.

3. Co-Mo-Er according to claim 1 or 2₂O₃A coating layer, wherein said Er₂O₃The size of the nanoparticles is 45-55nm, preferably 50 nm.

4. Co-Mo-Er according to claim 1 or 2₂O₃A coating layer, characterized in that said Co-Mo-Er₂O₃In the plating layer, the mass fraction of Co is 60-65%, and the mass ratio of Co to Mo is (1.8-1.9): 1.

5. the Co-Mo-Er of any one of claims 1 to 4₂O₃The preparation method of the coating is characterized in that a two-electrode system is adopted, and Co-Mo-Er is formed on the surface of a matrix through direct current deposition under the condition of constant-temperature water bath stirring₂O₃And (7) plating.

6. The Co-Mo-Er of claim 5₂O₃The preparation method of the plating layer is characterized in that the electroplating solution used in the direct current electrodeposition comprises cobalt sulfate, sodium molybdate, erbium oxide nano particles and a dispersing agent; the sodium dodecyl sulfate.

7. The Co-Mo-containing material as defined in claim 6Er₂O₃The preparation method of the plating layer is characterized in that the electroplating solution comprises the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate, 44.1mol/L of sodium citrate, 0.25g/L to 1g/L of erbium oxide nano particles and 1g/L of sodium dodecyl sulfate; the pH value is 6-8.

8. The Co-Mo-Er of claim 7₂O₃The preparation method of the plating layer is characterized in that the electroplating solution is prepared by the following method: firstly, uniformly mixing cobalt sulfate, sodium molybdate and sodium citrate to obtain a mixed solution A; mixing part of the mixed solution A with the erbium oxide nano particles and the sodium dodecyl sulfate, and grinding to obtain mixed solution B; mixing the mixed solution B with the rest mixed solution A;

preferably, the part of the mixed liquor A with the erbium oxide nano-particles accounts for 1/20-1/10 of the total mass of the mixed liquor A.

9. Co-Mo-Er according to any one of claims 5 to 8₂O₃The preparation method of the coating is characterized in that the conditions of the direct current electrodeposition are as follows: the constant current density is 2-4A/dm²The deposition time is 2-2.5 h;

the two electrode bodies take a conductive substrate as a cathode and a double graphite electrode as an anode;

the temperature of the constant water bath is 35-50 ℃; the stirring speed is 340-.

10. The Co-Mo-Er of any one of claims 1 to 4₂O₃The coating is applied to the field of electrocatalytic hydrogen evolution.

Technical Field

The invention relates to the technical field of electroplating, in particular to Co-Mo-Er₂O₃A plating layer and a preparation method and application thereof.

Background

Molybdenum is a silver-white metal and has the advantages of high melting point, small expansion coefficient, high conductivity, good heat-conducting property and the like. The binary molybdenum-containing alloy has more excellent conductivity, long-term electrochemical stability, good catalytic activity, excellent wear resistance, corrosion resistance and high-temperature oxidation resistance, so that the binary molybdenum-containing alloy has wide application in the fields of electro-catalytic hydrogen evolution, aerospace, military industry and the like.

Among the existing binary molybdenum-containing alloys, the Co-Mo alloy is widely concerned about due to the excellent performance, but the hydrogen evolution performance is poor, and the requirement of industrial development is difficult to meet, so that the improvement is urgently needed.

At present, more methods are used for improving the hydrogen evolution performance of Co-Mo alloy. For example, when the current density of the Co-Mo-P @ NPS electrode material prepared by the porzite reaches 10mA/cm²When the material is used, the hydrogen evolution overpotential of the material is 93 mV. When the current density of the Co/MoN nano-array prepared by Junwei Sun et al reaches 10mA/cm²When the material is used, the hydrogen evolution overpotential of the material is 52 mV.

Although the improving method can effectively improve the hydrogen evolution performance of the Co-Mo alloy, the method also has the defects of complex process, high cost, poor repeatability and the like.

Disclosure of Invention

The first aspect of the invention provides Co-Mo-Er₂O₃And (7) plating.

The invention provides Co-Mo-Er₂O₃The coating is an amorphous alloy coating which takes Co-Mo alloy as a main phase and Er₂O₃The nanoparticles are the doped phase.

The research of the invention finds that the rare earth material Er is prepared by mixing the rare earth material Er₂O₃The nano particles are doped into the Co-Mo alloy main phase, and can generate synergistic action with the main phase, thereby obviously improving the hydrogen evolution performance of the Co-Mo plating layer by electrolyzing water.

The invention further researches to discover that Er₂O₃Doping ratio of nano particles to Co-Mo-Er₂O₃The performance of the plating layer for hydrogen evolution by electrolyzing water has substantial influence; if the doping amount is too much, the agglomeration phenomenon is serious; but do notThe doping amount is too small, and the improvement of the hydrogen evolution performance of the electrolytic water is not obvious enough. For this purpose, the invention controls the Er₂O₃The doping ratio of the nano particles is Co-Mo-Er₂O₃6-8% of the total mass of the plating layer. By controlling Er₂O₃Doping ratio of nanoparticles to Er₂O₃The nano particles are better dispersed in the plating layer, thereby being beneficial to further improving the hydrogen evolution performance of the electrolyzed water.

The invention further researches to discover that Er₂O₃Size range of nanoparticles for their Co-Mo-Er₂O₃Degree of dispersion in the coating and Co-Mo-Er₂O₃The roughness of the coating has a substantial effect, which in turn affects the hydrogen evolution activity of the coating. For this purpose, the invention controls the Er₂O₃The size of the nanoparticles is 45-55nm, preferably 50 nm. By controlling the size range, the alloy can be compatible with Co-Mo-Er₂O₃Uniformity of dispersion in the coating and Co-Mo-Er₂O₃The roughness of the plating layer is beneficial to improving the hydrogen evolution performance of the plating layer by electrolyzing water.

The invention further researches and discovers that the Co-Mo-Er₂O₃Mass ratio of Co to Mo in main phase of coating to Co-Mo-Er₂O₃The hydrogen evolution performance of the electrolyzed water of the plating layer has a substantial influence. If the content of molybdenum in the plating solution is too high, the content of molybdenum oxide in the main phase of the plating layer is too high, so that the alloy structure of the plating layer is changed, and the surface of the plating layer is easy to fall off, so that the deposition of oxidation baits is hindered. Therefore, the invention controls the Co-Mo-Er₂O₃In the plating layer, the mass fraction of Co is 60-65%, and the mass ratio of Co to Mo is (1.8-1.9): 1. the problem is solved by controlling the mass ratio of Co to Mo, and the improvement of the hydrogen evolution performance of the electrolyzed water is facilitated. Preferably, the mass fraction of Co is 60.71%, and the mass fraction of Mo is 33.5%.

The Co-Mo-Er of the invention₂O₃The plating layer is formed on the surface of the substrate.

The second aspect of the present invention provides the above-mentioned Co-Mo-Er₂O₃A preparation method of the plating layer.

The Co-Mo-Er provided by the invention₂O₃A method of preparing a coating comprising: adopting a two-electrode system, and forming Co-Mo-Er on the surface of a matrix by direct current deposition under the stirring condition of constant-temperature water bath₂O₃And (7) plating.

The research of the invention finds that Er exists₂O₃The incorporation of the nanoparticles contributes to the improvement of the hydrogen evolution activity of the plating layer, but the nanoparticles are easily unevenly dispersed in the plating layer, thereby affecting the exertion degree of the effect. Some more advanced doping methods can increase Er₂O₃The dispersion degree of the nano particles is too high, but the cost is too high, the process is complex and the operability is poor. Therefore, the invention provides a method for preparing Co-Mo-Er by adopting a direct current deposition method₂O₃The method has the advantages of simple process, fast deposition, compact plating layer, high purity, strong operability, low cost and the like, and is expected to be widely applied in industry.

The electroplating solution adopted by the preparation method disclosed by the invention comprises a cobalt source, a molybdenum source and erbium oxide nano particles, and also comprises a dispersing agent so as to improve the dispersion degree of the erbium oxide nano particles in the electroplating solution.

Preferably, the cobalt source is cobalt sulfate, the molybdenum source is sodium molybdate, and the dispersant is sodium dodecyl sulfate. Compared with other dispersing agents, the matching degree of the sodium dodecyl sulfate, the cobalt sulfate, the sodium molybdate and the erbium oxide nano particles is higher, and the agglomeration phenomenon of the erbium oxide nano particles can be improved more obviously, so that the composite codeposition of the erbium oxide nano particles and metal is realized, and the electrolytic water hydrogen evolution performance of the alloy is improved.

As one embodiment of the present invention, the plating solution comprises the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate, 44.1mol/L of sodium citrate, 0.25g/L to 1g/L of erbium oxide nano particles and 1g/L of sodium dodecyl sulfate; the pH value is 6-8. By controlling the concentration of each raw material, a high-quality coating with good compactness and Er is obtained₂O₃Uniform doping, proper proportion and the like.

The electroplating solution is prepared by the following method: firstly, uniformly mixing cobalt sulfate, sodium molybdate and sodium citrate to obtain a mixed solution A; mixing part of the mixed solution A with the erbium oxide nano particles and the sodium dodecyl sulfate, and grinding to obtain mixed solution B; and mixing the mixed solution B with the rest mixed solution A. Through batch mixing, the erbium oxide nano particles are more favorably and uniformly dispersed in the electroplating solution, and a more uniform coating is obtained. Preferably, the part of the mixed liquor A with the erbium oxide nano-particles accounts for 1/20-1/10 of the total mass of the mixed liquor A.

In the preparation method, the conditions of the direct current electrodeposition are as follows: the constant current density is 2-4A/dm²The deposition time is 2-2.5 h. By controlling the constant current density and the deposition time, the obtained coating is more compact and uniform, and the hydrogen evolution activity is better.

In the preparation method, the two electrode bodies use a conductive substrate as a cathode and a double graphite electrode as an anode. Preferably, the conductive substrate is a copper sheet or a stainless steel sheet.

For better deposition, the conductive substrate may be pretreated prior to electrodeposition. The pretreatment comprises the following steps: and sequentially grinding the copper sheet by using 600-mesh and 2000-mesh sand paper, then polishing by using polishing solutions with the particle sizes of 6 micrometers, 3 micrometers and 1 micrometer, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes of ultrasonic treatment, finally cleaning by using a large amount of deionized water and drying by blowing.

The temperature of the constant water bath is 35-50 ℃; the stirring speed is 340-360rpm, preferably 350rpm, so as to ensure the deposition effect, avoid uneven coating and poor compactness caused by over-high speed, and avoid over-low production efficiency due to over-low speed, which is difficult to meet the industrial production requirement.

As one embodiment of the invention, the Co-Mo-Er₂O₃The preparation method of the plating layer comprises the following specific steps:

(1) the method comprises the following steps of sequentially grinding a copper sheet with the thickness of 6mm, 10mm and 1mm by using sand paper with the meshes of 600 and 2000, polishing by using polishing solutions with the thicknesses of 6 mu m, 3 mu m and 1 mu m, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes, washing by using a large amount of deionized water and drying by blowing.

(2) Preparing electroplating solution containing cobalt sulfate, sodium molybdate and sodium citrate. The concentration of each component of the electroplating solution is as follows: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate and 44.1mol/L of sodium citrate.

(3) Mixing a certain amount of erbium oxide nanoparticles, sodium dodecyl sulfate and a proper amount of electroplating solution, grinding in a mortar, uniformly mixing with the rest electroplating solution, fixing the volume, and adjusting the pH of the solution to 6-8 by using sodium hydroxide or dilute sulfuric acid.

The size of the erbium oxide nano particles is 50nm, the concentration of the erbium oxide nano particles is 0.25g/L-1g/L, and the concentration of the sodium dodecyl sulfate is 1 g/L.

(4) The treated copper sheet is used as a cathode, a double graphite plate is used as an anode, the stirring speed is controlled to be 350rpm under the constant-temperature water bath heating condition of 35-50 ℃, and the constant current density is 2-4A/dm²Then, electro-deposition is carried out for 2 h.

(5) After the electrodeposition is finished, taking out the copper sheet, washing the copper sheet by deionized water, and drying to obtain the Co-Mo-Er₂O₃And (7) plating.

The third aspect of the invention provides the application of the coating in the field of electrocatalytic hydrogen evolution.

The invention has the following beneficial effects:

the invention provides Co-Mo-Er₂O₃The plating layer has a rough surface structure and a large electrochemical active area; compared with no Er₂O₃The added Co-Mo plating layer has more excellent hydrogen evolution performance. Meanwhile, the invention adopts an electrodeposition method to prepare Co-Mo-Er₂O₃And (7) plating. The method has the advantages of simple process, low cost and high repeatability, and can be widely applied to industry.

Drawings

FIG. 1 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃SEM image of the plating layer.

FIG. 2 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃EDS energy spectrum of the coating.

FIG. 3 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃Co element in the coatingDistribution diagram of Mo element, Er element and O element.

Wherein, (a) a distribution diagram of Co element; (b) is a distribution diagram of Mo element; (c) is a distribution diagram of Er element; (d) is a distribution diagram of the O element.

FIG. 4 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃XRD pattern of the plating.

FIG. 5 shows Co-Mo-Er obtained in various embodiments of the present invention₂O₃Electrolytic water hydrogen evolution curves for the plating and the Co-Mo plating.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Each of the components in the following examples is commercially available.

Example 1

This example provides a Co-Mo-Er₂O₃The preparation method of the plating layer comprises the following specific steps:

(1) the method comprises the following steps of sequentially grinding a copper sheet with the thickness of 6mm, 10mm and 1mm by using sand paper with the meshes of 600 and 2000, polishing by using polishing solutions with the thicknesses of 6 mu m, 3 mu m and 1 mu m, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes, washing by using a large amount of deionized water and drying by blowing.

(2) Preparing an electroplating solution with the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate and 44.1mol/L of sodium citrate.

Mixing erbium oxide nanoparticles, sodium dodecyl sulfate and 5ml of electroplating solution, wherein the mass concentration of the erbium oxide nanoparticles is 1g/L, and the mass concentration of the sodium dodecyl sulfate is 1 g/L; grinding in a mortar for 15 minutes, mixing with the residual electroplating solution of 95ml, and fixing the volume.

(3) In a double-electrode system, a treated copper sheet is used as a cathode, and a double graphite plate is used as an anode. Heating the water bath kettle by magnetic force, controlling the temperature at 45 ℃, the stirring speed at 350rpm, and controlling the current density of the cathode at 4A/dm²And depositing for 2 hours at constant current.

After deposition is finished, taking out the coating, washing the coating by using a large amount of deionized water, and drying to obtain the Co-Mo-Er₂O₃And (7) plating.

The results show that the obtained Co-Mo-Er₂O₃In the coating, the mass fraction of Co is 58.86%, the mass fraction of Mo is 36.93%, Er₂O₃The mass fraction of (a) is 3.5%.

Er₂O₃The size of the nanoparticles was 50 nm.

And (3) testing the performance of hydrogen evolution by electrolyzed water:

adopting an electrochemical three-electrode system to mix Co-Mo-Er₂O₃The plating layer is used as a working electrode, a graphite electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and Co-Mo-Er is subjected to counter treatment in 1mol/LKOH solution₂O₃And (5) testing the performance of the electrolytic water for hydrogen evolution of the plating layer. The test was performed at room temperature, and the electrodes were stabilized in the electrolyte for a period of time before the test, and a stable open circuit potential was tested.

The hydrogen evolution curve is obtained by testing under-1.2V to 0.9V (relative to a saturated calomel electrode) by adopting a linear sweep voltammetry method, and when the current density reaches 5mA cm^-2When the coating is used, the overpotential for hydrogen evolution is 51mV, which is 44mV lower than that of Co-Mo coating.

When the current density reaches 10mA cm^-2The overpotential for hydrogen evolution is 81 mV.

When the current density reaches 20mA cm^-2The overpotential for hydrogen evolution was 107 mV.

Example 2

This example provides a Co-Mo-Er₂O₃The preparation method of the plating layer comprises the following specific steps:

(1) the method comprises the following steps of sequentially grinding a copper sheet with the thickness of 6mm, 10mm and 1mm by using sand paper with the meshes of 600 and 2000, polishing by using polishing solutions with the thicknesses of 6 mu m, 3 mu m and 1 mu m, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes, washing by using a large amount of deionized water and drying by blowing.

(2) Preparing an electroplating solution with the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate and 44.1mol/L of sodium citrate.

Mixing erbium oxide nanoparticles, sodium dodecyl sulfate and 5ml of electroplating solution, wherein the mass concentration of the erbium oxide nanoparticles is 0.75g/L, and the mass concentration of the sodium dodecyl sulfate is 1 g/L; grinding in a mortar for 15 minutes, mixing with the residual electroplating solution of 95ml, and fixing the volume.

(3) In a double-electrode system, a treated copper sheet is used as a cathode, and a double graphite plate is used as an anode. Heating the water bath kettle by magnetic force, controlling the temperature at 45 ℃, the stirring speed at 350rpm, and controlling the current density of the cathode at 4A/dm²And depositing for 2 hours at constant current.

After deposition is finished, taking out the coating, washing the coating by using a large amount of deionized water, and drying to obtain the Co-Mo-Er₂O₃And (7) plating.

The results show that the obtained Co-Mo-Er₂O₃In the coating, the mass fraction of Co is 61.14%, the mass fraction of Mo is 35.16%, and Er₂O₃The mass fraction of (2.9%).

Er₂O₃The size of the nanoparticles was 50 nm.

And (3) testing the performance of hydrogen evolution by electrolyzed water:

adopting an electrochemical three-electrode system to mix Co-Mo-Er₂O₃The plating layer is used as a working electrode, a graphite electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and Co-Mo-Er is subjected to counter treatment in 1mol/LKOH solution₂O₃And (5) testing the performance of the electrolytic water for hydrogen evolution of the plating layer. The test was performed at room temperature, and the electrodes were stabilized in the electrolyte for a period of time before the test, and a stable open circuit potential was tested.

The hydrogen evolution curve is obtained by testing under-1.2V to 0.9V (relative to a saturated calomel electrode) by adopting a linear sweep voltammetry method, and when the current density reaches 5mA cm^-2When the coating is used, the hydrogen evolution overpotential is 48mV, which is 47mV lower than that of the Co-Mo coating.

When the current density reaches 10mA cm^-2The overpotential for hydrogen evolution is 78 mV.

When the current density reaches 20mA cm^-2When the reaction is carried out, the overpotential for hydrogen evolution is 103 mV.

Example 3

This example provides a Co-Mo-Er₂O₃Coating layerThe preparation method comprises the following specific steps:

(1) the method comprises the following steps of sequentially grinding a copper sheet with the thickness of 6mm, 10mm and 1mm by using sand paper with the meshes of 600 and 2000, polishing by using polishing solutions with the thicknesses of 6 mu m, 3 mu m and 1 mu m, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes, washing by using a large amount of deionized water and drying by blowing.

(2) Preparing an electroplating solution with the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate and 44.1mol/L of sodium citrate.

Mixing erbium oxide nanoparticles, sodium dodecyl sulfate and 5ml of electroplating solution, wherein the mass concentration of the erbium oxide nanoparticles is 0.5g/L, and the mass concentration of the sodium dodecyl sulfate is 1 g/L; grinding in a mortar for 15 minutes, mixing with the residual electroplating solution of 95ml, and fixing the volume.

(3) In a double-electrode system, a treated copper sheet is used as a cathode, and a double graphite plate is used as an anode. Heating the water bath kettle by magnetic force, controlling the temperature at 45 ℃, the stirring speed at 350rpm, and controlling the current density of the cathode at 4A/dm²And depositing for 2 hours at constant current.

After deposition is finished, taking out the coating, washing the coating by using a large amount of deionized water, and drying to obtain the Co-Mo-Er₂O₃And (7) plating.

The results show that the obtained Co-Mo-Er₂O₃In the coating, the mass fraction of Co is 60.71%, the mass fraction of Mo is 33.5%, Er₂O₃The mass fraction of (b) is 4.7%.

Er₂O₃The size of the nanoparticles was 50 nm.

FIG. 1 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃SEM image of the plating layer.

FIG. 2 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃EDS energy spectrum of the coating.

FIG. 3 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃Distribution diagram of Co element, Mo element, Er element and O element in the coating. Wherein, (a) a distribution diagram of Co element; (b) is a distribution diagram of Mo element; (c) is a distribution diagram of Er element; (d) is a distribution diagram of the O element.

FIG. 4 shows the Co-Mo-Er obtained in example 3 of the present invention₂O₃XRD pattern of the plating.

And (3) testing the performance of hydrogen evolution by electrolyzed water:

adopting an electrochemical three-electrode system to mix Co-Mo-Er₂O₃The plating layer is used as a working electrode, a graphite electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and Co-Mo-Er is subjected to counter treatment in 1mol/LKOH solution₂O₃And (5) testing the performance of the electrolytic water for hydrogen evolution of the plating layer. The test was performed at room temperature, and the electrodes were stabilized in the electrolyte for a period of time before the test, and a stable open circuit potential was tested.

The hydrogen evolution curve is obtained by testing under-1.2V to 0.9V (relative to a saturated calomel electrode) by adopting a linear sweep voltammetry method, and when the current density reaches 5mA cm^-2When the coating is used, the hydrogen evolution overpotential is 37mV, which is 58mV lower than that of the Co-Mo coating.

When the current density reaches 10mA cm^-2The overpotential for hydrogen evolution is 66 mV.

When the current density reaches 20mA cm^-2The overpotential for hydrogen evolution is 95 mV.

Example 4

This example provides a Co-Mo-Er₂O₃The preparation method of the plating layer comprises the following specific steps:

(1) the method comprises the following steps of sequentially grinding a copper sheet with the thickness of 6mm, 10mm and 1mm by using sand paper with the meshes of 600 and 2000, polishing by using polishing solutions with the thicknesses of 6 mu m, 3 mu m and 1 mu m, respectively soaking in a sodium hydroxide solution and a dilute sulfuric acid solution for 10 minutes, placing in alcohol for 5 minutes, washing by using a large amount of deionized water and drying by blowing.

(2) Preparing an electroplating solution with the following components: 28.1g/L of cobalt sulfate, 12.1g/L of sodium molybdate and 44.1mol/L of sodium citrate.

Mixing erbium oxide nanoparticles, sodium dodecyl sulfate and 5ml of electroplating solution, wherein the mass concentration of the erbium oxide nanoparticles is 0.25g/L, and the mass concentration of the sodium dodecyl sulfate is 1 g/L; grinding in a mortar for 15 minutes, mixing with the residual electroplating solution of 95ml, and fixing the volume.

(3) In the case of a two-electrode system,the treated copper sheet is used as a cathode, and the double graphite plates are used as anodes. Heating the water bath kettle by magnetic force, controlling the temperature at 45 ℃, the stirring speed at 350rpm, and controlling the current density of the cathode at 4A/dm²And depositing for 2 hours at constant current.

After deposition is finished, taking out the coating, washing the coating by using a large amount of deionized water, and drying to obtain the Co-Mo-Er₂O₃And (7) plating.

The results show that the obtained Co-Mo-Er₂O₃In the coating, the mass fraction of Co is 61.29%, the mass fraction of Mo is 34.9%, Er₂O₃The mass fraction of (a) is 1.3%.

Er₂O₃The size of the nanoparticles was 50 nm.

And (3) testing the performance of hydrogen evolution by electrolyzed water:

adopting an electrochemical three-electrode system to mix Co-Mo-Er₂O₃The plating layer is used as a working electrode, a graphite electrode is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and Co-Mo-Er is subjected to counter treatment in 1mol/LKOH solution₂O₃And (5) testing the performance of the electrolytic water for hydrogen evolution of the plating layer. The test was performed at room temperature, and the electrodes were stabilized in the electrolyte for a period of time before the test, and a stable open circuit potential was tested.

The hydrogen evolution curve is obtained by testing under-1.2V to 0.9V (relative to a saturated calomel electrode) by adopting a linear sweep voltammetry method, and when the current density reaches 5mA cm^-2When the coating is used, the hydrogen evolution overpotential is 64mV, which is 31mV lower than that of the Co-Mo coating.

When the current density reaches 10mA cm^-2When the reaction is carried out, the overpotential for hydrogen evolution is 93 mV.

When the current density reaches 20mA cm^-2The overpotential for hydrogen evolution is 109 mV.

FIG. 5 shows Co-Mo-Er obtained in various embodiments of the present invention₂O₃Electrolytic water hydrogen evolution curves for the plating and the Co-Mo plating.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.