Preparation method and application of reversible hydrogen electrode

Abstract

The invention discloses a preparation method and application of a reversible hydrogen electrode. The preparation method comprises the following steps: (I) pretreating the surface of a conductive substrate; (2) loading a catalyst layer on the surface of the pretreated conductive substrate; (3) loading a hydrophobic and aerophilic coating on the surface of the catalyst layer; and the like. The prepared reversible hydrogen electrode is applied to rapid measurement of the potential of a reference electrode on the reversible hydrogen electrode scale. The reversible hydrogen electrode prepared by the method disclosed by the invention can be applied to electrolyte with any pH, hydrogen does not need to be introduced into the whole electrolyte, a few hydrogen bubbles are generated by electrolysis within several seconds and attached to the surface of the reversible hydrogen electrode, and a hydrogen-saturated local microenvironment is generated on the surface of the reversible hydrogen electrode; the accurate potential value of the reference electrode relative to the reversible hydrogen electrode can be obtained. The method is low in cost, easy and convenient to operate and short in consumed time, the problem of potential deviation after the reference electrode is aged can be effectively solved, and the precision of electrochemical measurement is improved.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical measurement, and in particular relates to a preparation method and application of a reversible hydrogen electrode. Background Art

[0002] The evaluation of many electrocatalytic reactions (such as oxygen evolution reaction, hydrogen evolution reaction, organic oxidation / reduction reaction, nitrate reduction reaction, etc.) depends on the potential of the working electrode relative to the reversible hydrogen electrode, which is often obtained indirectly through commercial reference electrodes (such as calomel electrode, silver-silver chloride electrode, mercury-mercuric oxide electrode, mercury-mercurous sulfate electrode, etc.). However, as the reference electrode ages, the potential of these reference electrodes cannot always be guaranteed to be stable. In addition, even for new electrodes, the potential of the reference electrode sometimes deviates from the theoretical value due to the existence of the liquid junction potential. Therefore, it is necessary to use a real reversible hydrogen electrode in the experiment to calibrate the reference electrode potential.

[0003] There are currently two commercial reversible hydrogen electrodes on the market. One is the German brand HydroFlex, which has not been widely promoted due to its high price (25 to 80 times that of ordinary commercial reference electrodes) and short service life (6 months for each hydrogen tank); the other is the reversible hydrogen electrode produced by the Japanese brand ALS, which uses hydrogen produced by electrolysis, but its narrow pH tolerance range (0 to 9) limits its use. In addition to commercial reversible hydrogen electrodes, there are also literature reports on homemade reversible hydrogen electrodes. The paper (J. Electrochem. Soc., 2022169066505) uses the most traditional and most commonly used method for making reversible hydrogen electrodes. Pure hydrogen is introduced into the solution to make it saturated with hydrogen, and the reversible hydrogen electrode potential is obtained by immersing platinum wire in it. However, this method has certain safety risks because it requires a long time to pass flammable and explosive pure hydrogen. In addition, hydrogen can also be produced by electrolysis of metal wires in electrode tubes, but it generally takes a long time (>10 min) to produce enough hydrogen, which is time-consuming (such as patent CN214252133U), and when dissolved oxygen is mixed into the internal solution, it will produce an imperceptible potential deviation and cause experimental errors. Most reports (such as patents CN205679564U and CN220188417U, paper ACS Catal.2023,13,8073-8079) use glass electrode shells, which are complex in structure and high in manufacturing cost, and the use of glass will cause pollution to the alkaline electrolyte.

[0004] In summary, there is still a lack of a method for potential correction of a reference electrode on the reversible hydrogen electrode scale that is cheap, simple, safe, fast, and will not contaminate the electrolyte. Summary of the invention

[0005] The present invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a preparation method and application of a reversible hydrogen electrode.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a reversible hydrogen electrode comprises the following steps:

[0008] (I) pretreating the surface of the conductive substrate;

[0009] (II) loading a catalyst layer on the surface of a pretreated conductive substrate;

[0010] (III) A hydrophobic and air-philic coating is loaded on the surface of the catalyst layer.

[0011] In the above technical solution, the pretreatment of the surface of the conductive substrate includes any one or a combination of degreasing, pickling, alkali cleaning, etching, grinding, sandblasting, polishing or ultrasonic cleaning.

[0012] In the above technical solution, the conductive substrate is any one of carbon, conductive glass, metal or metal alloy; the metal is any one of magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold, cadmium, tin, bismuth or lead; the metal alloy is an alloy composed of any several of magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold, cadmium, tin, bismuth or lead; the shape of the conductive substrate is any one of filament, columnar, mesh, sheet, fiber felt or foam.

[0013] In the above technical scheme, the loading method of the catalyst layer is selected from any one or a combination of electrochemical deposition, electrophoretic deposition, vapor deposition, electroplating, chemical plating, hydrothermal deposition, sol-gel method, coating, cladding, melting, dipping, sintering, drip coating, brush coating, roller coating, spray coating, scraping, spin coating, slit coating, rod coating, and dip coating.

[0014] In the above technical solution, the catalyst layer is any one of platinum, palladium, rhodium, iridium, ruthenium or nickel, or an alloy composed of several of them.

[0015] In the above technical solution, the hydrophobic and air-philic coating is any one or a mixture of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), fluorinated ethylene propylene copolymer (FEP), polyperfluoroalkoxy vinyl ether (ECTFE), polytetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), perfluorinated sulfonic acid resin (Nafion), polyolefin, polyester, polyamide, polyacrylonitrile, paraffin or silicone material.

[0016] In the above technical scheme, the loading method of the hydrophobic and air-philic coating is selected from any one or a combination of electrochemical deposition, electrophoretic deposition, vapor deposition, electroplating, chemical plating, hydrothermal deposition, sol-gel method, surface polymerization, coating, cladding, welding, dipping, sintering, drip coating, brush coating, roller coating, spray coating, scraper coating, spin coating, slit coating, rod coating, and dip coating.

[0017] The invention relates to an application of a reversible hydrogen electrode prepared by the aforementioned method in the rapid measurement of the reference electrode potential on the reversible hydrogen electrode scale.

[0018] In the above technical scheme, the specific method for rapid measurement of the reference electrode potential on the reversible hydrogen electrode scale is: using the reversible hydrogen electrode prepared by the method described in one of claims 1 to 7 as a working electrode, and forming a three-electrode system with the reference electrode to be measured, the counter electrode and the electrolyte to be measured; applying a cathode current to the working electrode for a certain period of time, then cutting off the cathode current, and then measuring the open circuit voltage within a certain period of time; the negative value of the measured open circuit voltage is the accurate potential of the reference electrode on the reversible hydrogen electrode scale.

[0019] In the above technical solution, the cathode current is 1 μA to 1 A; the cathode current is applied for 1 ms to 1 min; and the open circuit voltage is measured for 0 s to 1 min.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a preparation method and application of a reversible hydrogen electrode. The reversible hydrogen electrode prepared according to the method of the present invention can be reused for measuring the accurate potential of the reference electrode on the scale of the reversible hydrogen electrode, so as to achieve low-cost, safe, fast and accurate electrochemical measurement. The reversible hydrogen electrode of the present invention is applicable to a wide range of electrolyte pH (pH = 0 to 14), and there is no need to use a hydrogen cylinder or a hydrogen generator with potential safety hazards, nor is there a need for a long time (> 10min) of electrolysis to produce hydrogen like the previous reversible hydrogen electrode. Only a few seconds of electrolysis are required to produce a small amount of hydrogen bubbles, and the hydrogen bubbles are adhered to the electrode surface by using a hydrophobic and aerophilic coating, and a local microenvironment saturated with hydrogen is formed in the solution on the electrode surface, so that an accurate reference electrode relative to the reversible hydrogen electrode can be obtained. The present invention uses non-precious metals (such as titanium wire) as the electrode body, and the consumption of precious metals is small, which can significantly reduce costs; and without using a glass shell, there is no risk of contaminating the electrolyte and generating a liquid junction potential. The invention has the characteristics of low cost, simple operation and short time consumption (<2min), can effectively eliminate the error caused by the potential deviation after the reference electrode ages, and improves the accuracy of electrochemical measurement. DETAILED DESCRIPTION

[0022] In order to enable persons skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below through specific implementation methods.

[0023] Example 1

[0024] A method for preparing a reversible hydrogen electrode specifically comprises the following steps:

[0025] (i) Surface treatment of conductive substrate

[0026] A titanium wire (length 3 cm, diameter 0.3 mm) was placed in anhydrous ethanol and ultrasonicated for 10 minutes; then the titanium wire was rinsed with deionized water; then the titanium wire was placed in hydrochloric acid (36 wt%) and soaked at room temperature for 10 minutes; finally, the titanium wire was rinsed with deionized water;

[0027] (ii) Support of catalyst layer

[0028] Chloroplatinic acid (2 wt %) solution was used as the electroplating solution, the titanium wire was used as the cathode, and the platinum wire was used as the anode. The electroplating was performed at a cathode current of -5 mA for 60 seconds, and then the platinum-black plated titanium wire was rinsed clean with deionized water.

[0029] (iii) Loading of hydrophobic and aerophilic coating

[0030] The titanium wire coated with platinum black was immersed in a PTFE dispersion (5 wt%) and then dried, and then sintered at 320° C. for 1 h to obtain a reversible hydrogen electrode.

[0031] Example 2

[0032] A specific step of measuring the electrode potential of a mercury-mercury oxide (Hg / HgO) reference electrode in 1M KOH (pH=14) relative to the reversible hydrogen electrode prepared in Example 1 is as follows:

[0033] The reversible hydrogen electrode prepared in Example 1 was used as the working electrode, the Hg / HgO electrode to be tested was used as the reference electrode, the platinum wire was used as the counter electrode, and the electrolyte was 1M KOH; the platinum-plated black part of the reversible hydrogen electrode was completely immersed below the liquid surface, a cathode current of -5 mA was applied to the reversible hydrogen electrode for 1 s, and then the power was turned off and the open circuit voltage within 20 s was measured to be -0.929 V, and the potential of the Hg / HgO electrode to be tested in 1M KOH was obtained to be +0.929 V vs. RHE (relative reversible hydrogen electrode).

[0034] Example 3

[0035] A specific step of measuring the electrode potential of a calomel (Hg / Hg2Cl2) reference electrode in 1.2M HCl (pH=0) relative to the reversible hydrogen electrode prepared in Example 1 is as follows:

[0036] The reversible hydrogen electrode prepared in Example 1 was used as the working electrode, the Hg / Hg2Cl2 electrode to be tested was used as the reference electrode, the platinum wire was used as the counter electrode, and the electrolyte was 1.2M HCl; the platinum-plated black part of the reversible hydrogen electrode prepared in Example 1 was completely immersed below the liquid surface, a cathode current of -5 mA was applied to the reversible hydrogen electrode for 1 s, and then the power was turned off and the open circuit voltage within 20 s was measured to be -0.246 V, and the potential of the Hg / Hg2Cl2 electrode to be tested in 1.2M HCl was obtained to be +0.246 V vs. RHE (relative reversible hydrogen electrode).

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a reversible hydrogen electrode, characterized in that: The following steps are involved: (I) pretreating the surface of the conductive substrate; (II) loading a catalyst layer on the surface of a pretreated conductive substrate; (III) A hydrophobic and air-philic coating is loaded on the surface of the catalyst layer.

2. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The pretreatment of the surface of the conductive substrate includes any one or a combination of degreasing, pickling, alkali cleaning, etching, grinding, sandblasting, polishing or ultrasonic cleaning.

3. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The conductive substrate is any one of carbon, conductive glass, metal or metal alloy; the metal is any one of magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold, cadmium, tin, bismuth or lead; the metal alloy is an alloy composed of any several of magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, gold, cadmium, tin, bismuth or lead; the shape of the conductive substrate is any one of filament, columnar, mesh, sheet, fiber felt or foam.

4. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The catalyst layer is loaded by any one or a combination of electrochemical deposition, electrophoretic deposition, vapor deposition, electroplating, chemical plating, hydrothermal deposition, sol-gel method, coating, cladding, melting, dipping, sintering, drip coating, brush coating, roller coating, spray coating, scraper coating, spin coating, slit coating, rod coating or dip coating.

5. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The catalyst layer is any one of platinum, palladium, rhodium, iridium, ruthenium or nickel, or an alloy composed of several of them.

6. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The hydrophobic and air-philic coating is any one or a mixture of polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polyperfluoroalkoxy vinyl ether, polytetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, perfluorinated sulfonic acid resin, polyolefin, polyester, polyamide, polyacrylonitrile, paraffin or silicone material.

7. The method for preparing a reversible hydrogen electrode according to claim 1, characterized in that: The loading method of the hydrophobic and air-philic coating is any one of electrochemical deposition, electrophoretic deposition, vapor deposition, electroplating, chemical plating, hydrothermal deposition, sol-gel method, surface polymerization, coating, cladding, welding, dipping, sintering, drip coating, brush coating, roller coating, spray coating, scraper coating, spin coating, slit coating, rod coating or dip coating.

8. An application of a reversible hydrogen electrode prepared by the method according to any one of claims 1 to 7, characterized in that: Applied to the rapid measurement of reference electrode potential on the reversible hydrogen electrode scale.

9. The use of the reversible hydrogen electrode according to claim 8, characterized in that: The specific method for rapid measurement of the reference electrode potential on the reversible hydrogen electrode scale is: using the reversible hydrogen electrode prepared by the method described in any one of claims 1 to 7 as a working electrode, and forming a three-electrode system with the reference electrode to be measured, the counter electrode and the electrolyte to be measured; applying a cathode current to the working electrode for a certain period of time, then cutting off the cathode current, and then measuring the open circuit voltage within a certain period of time; the negative value of the measured open circuit voltage is the accurate potential of the reference electrode on the reversible hydrogen electrode scale.

10. The method for rapid correction of reference electrode potential on a reversible hydrogen electrode scale according to claim 8, characterized in that: The magnitude of the cathode current is 1 μA to 1 A; the time for applying the cathode current is 1 ms to 1 min; and the measurement time of the open circuit voltage is 0 s to 1 min.