CN1048295C

CN1048295C - Preparation for new evolving hydrogen reaction electrode

Info

Publication number: CN1048295C
Application number: CN95116198A
Authority: CN
Inventors: 胡伟康; 张允什; 宋德英; 周作祥; 汪根时
Original assignee: Nankai University
Current assignee: Nankai University
Priority date: 1995-11-03
Filing date: 1995-11-03
Publication date: 2000-01-12
Anticipated expiration: 2015-11-03
Also published as: CN1149633A

Abstract

The present invention relates to a novel electrode with high activity of hydrogen evolution reactions and strong resistance to power-cut short circuit, which belongs to the field of electrochemistry. The electrode at least contains alloy A with good electrocatalytic performance and alloy B with good hydrogen storage property. The electrode not only has good catalytic performance of the hydrogen evolution reactions and good electrochemical stability of long-term continuous electrolysis, but also has strong capacity for resisting power-cut short circuit and oxidizing corrosion.

Description

Preparation method of hydrogen evolution reaction electrode

The present invention belongs to the preparation of hydrogen evolution reaction electrode.

Currently, the most widely studied hydrogen evolution reaction electrode at home and abroad is mainly prepared from Raney Nickel (Raney Nickel) and Nickel-molybdenum alloy, and the Raney Nickel alloy has the advantages of large specific surface area, high porosity and the like. Recently, Raney nickel alloys prepared by the composite plating technique at 35% by weight NaOH at 90 ℃ and 200mA/cm were reported²When electrolyzing under current density, the overpotential of hydrogen evolution reaction is 80mV, and the electrochemical stability is better under the condition of continuous electrolysis. The nickel-molybdenum alloy is the most actively studied electrocatalytic alloy in recent years, and is not characterized by a porous structure like Raney nickel alloy. But the alloy shows high hydrogen evolution reactivity due to the d-electron synergistic effect. D.E.Brown et al report Ni prepared by pyrolysis hydrogen reduction₆₀Mo₄₀Alloy electrode is prepared at 30% KOH weight, 70 deg.C and 500mA/cm²(relative geometric area), after 11000 hours of continuous electrolysis, the overpotential of the reaction is 60 mV. The above two alloy electrodes are currently considered to be the most likely negative active materials for the chlor-alkali industry. However, during electrolysis, power failure frequently occurs, and under such discontinuous or intermittent electrolysis conditions (especially after two weeks of power failure), the catalytic activity of the raney nickel and nickel molybdenum alloy hydrogen evolution reaction is almost completely lost. Therefore, the existing hydrogen evolution reaction electrode material mainly has the defects of poor power failure short circuit resistance, easy corrosion and oxidation of the electrode material in the intermittent process and the like.

The invention aims to provide a preparation method of a hydrogen evolution reaction electrode, which can overcome the defects of poor catalytic activity and electrochemical stability and the like of the prior Raney nickel and nickel-molybdenum alloy electrode under the condition of intermittent electrolysis, particularly when power is off for more than two weeks.

The technical content of the invention comprises the design of the electrode structure and the components and the manufacture of the electrode. The electrode structure is mainly composed of the following 3 parts: namely the electrode skeleton, alloy a and alloy B. The alloy A mainly has the function of electrocatalysis performance, and ensures that the electrode has excellent hydrogen evolution reaction activity in the hydrogen evolution reaction process of the electrode. The function of alloy B is in the electrolytic processThe hydrogen storage agent plays a role in chemically absorbing part of hydrogen and storing the hydrogen; another function of alloy B is to electrochemically release hydrogen during the intermittent periods of power failure to ensure that alloy a is not significantly oxidized and corroded during the intermittent periods of electrode operation. According to the design of the electrode structure, the alloy A can be made of any one of Raney nickel alloy, nickel-molybdenum alloy and nickel-molybdenum-iron alloy. Alloy B may be made of LaNi₅Type, Ti-Ni series and multi-element mixed rare earth metal alloy MmNi₅Type, etc. hydrogen storage materials. The electrode manufacturing method comprises the following specific steps: firstly, preparing an alloy B by a smelting method, crushing a blocky alloy B by a mechanical method, selecting alloy powder with 200 meshes, adhering PVA latex on a porous nickel electrode framework, drying in the air, and modifying the surface of an electrode by a constant current electrodeposition method; the amorphous nickel-molybdenum alloy is selected as the alloy A layer of the novel electrode, and the preparation method is to use an electrodeposition method to precipitate the alloy A on the surface of the alloy B because the amorphous nickel-molybdenum alloy has high electrocatalytic performance. The electrodeposition composition and conditions were as follows: NiSO₄·6H₂O is 50-80 g/l; na (Na)₂MoO₄·2H₂O8-11 g/L; 30-50 g/L sodium citrate, the pH value of the solution is adjusted to 8.5-9.5 by using anhydrous sodium sulfate, and the cathode current density is 20-60 mA/cm²The temperature of the plating solution is 25 +/-5 ℃.

The invention not only has excellent electrochemical stability of long-term continuous electrolysis, but also has strong power failure short circuit resistance. The electrocatalytic performance of the electrode hydrogen evolution reaction mainly depends on the property of the surface amorphous nickel-molybdenum alloy, and when power failure short circuit occurs, the hydrogen storage alloy B in the electrode reversibly releases stored hydrogen through diffusion so as to counteract reverse current and protect the surface alloy A of the electrode from oxidation and corrosion:

wherein M is a transition metal element.

The invention can replace the existing iron cathode material (hydrogen evolution reaction potential is more than 300mV) in the chlor-alkali industry, greatly reduce the electrolysis energy consumption, improve the economic benefit, reduce the cathode hydrogen evolution overpotential by 200mV, and save 140 ℃ of electricity when producing 1 ton of caustic soda.

Made of rare earth alloy LaNi_4.9Si_0.1And an amorphous nickel-molybdenum alloy with a thickness of about 12 μm as a hydrogen evolution reaction cathode, while a large-area nickel strip was used as an anode. At 30% by weight of NaOH at 70 ℃ at 200mA/cm²After 4 months of continuous electrolysis, the potential of the electrode hydrogen evolution reaction is about 85mV, and the overpotential of the cathode hydrogen evolution reaction is about 88mV after the electrode is in power failure and short circuit for 2 weeks.

With a misch metal alloy MmNi_3.6Co_0.75Mn_0.42Al_0.27And an amorphous nickel-molybdenum alloy electrode with a thickness of about 12 μm as a hydrogen evolution cathode, wherein the anode adopts a large-area Pt wire mesh, and KOH with 30 weight percent is added at 70 ℃ and 200mA/cm²After 6 months of continuous electrolysis, the overpotential of the hydrogen evolution reaction is 80-85 mV. After the electrode is in power failure and short circuit for 3 weeks, the overpotential of the electrode hydrogen evolution reaction is increased by about 3-5 mV.

Claims

1. A method for preparing a hydrogen evolution reaction electrode is characterized in that the electrode consists of an electrode framework, an alloy A and an alloy B, wherein the alloy A is Raney nickel alloy, nickel-molybdenum alloy or nickel-molybdenum-iron alloy; alloy B is LaNi₅Type, Ti-Ni series or mixed rare earth metal alloy MmNi₅Molding; the preparation method comprises the following steps:

(1) preparing alloy B by a smelting method, crushing the massive alloy Bby a mechanical method, selecting alloy powder which is sieved by a 200-mesh sieve, and adhering PVA latex solution on a porous nickel electrode framework;

(2) drying, and modifying the surface of the electrode by using a constant current electrodeposition method;

(3) the surface of alloy B was further plated with a 12 μm thick layer of alloy A by electrodeposition under the following conditions: NiSO₄·6H₂The concentration of O is 50-80 g/l, Na₂MoO₄2H₂O is 8-11 g/l, sodium citrate is 30-50 g/l, the pH value of the solution is adjusted to 8.5-9.5 by using anhydrous sodium sulfate, and the cathode current density is 20-60 mA/cm²The temperature of the plating solution is 25 +/-5 ℃.