High Efficiency Electrodes for Alkaline Electrolysis of Water
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IED ELECTROCHEMISTRY AND METAL CORROSION PROTECTION
High Efficiency Electrodes for Alkaline Electrolysis of Water V. N. Kuleshova, N. V. Kuleshova,*, and S. V. Kurochkina a National
Research University “Moscow Power Engineering Institute,” Moscow, 111250 Russia *e-mail: [email protected] Received September 25, 2019; revised May 12, 2020; accepted June 5, 2020
Abstract—The paper presents a new porous coating of electrodes for water electrolyzers with an alkaline electrolyte, as well as methods for its modification with catalysts for the reaction of hydrogen and oxygen evolution. The coating is formed from a suspension of nickel-cobalt powder in an electroplating bath for applying a nickel-cobalt coating and is characterized by an acicular structure and a developed specific surface. Nickel-cobalt powder is obtained by thermal decomposition of mixed nickel-cobalt formate in 1,4-butanediol, which is a modifying additive for nickel plating bath. The results of studies of new electrode materials by physicochemical and electrochemical methods are reported. Keywords: alkaline electrolysis, porous nickel-cobalt coating of electrodes, thermal decomposition of metal formates in an environment of polyhydric alcohols DOI: 10.1134/S1070427220080066
Electrolyzers of water with an alkaline electrolyte have been used for many decades in nuclear and thermal energy, in the hydrogen cycle of energy storage generated by renewable energy sources. The main advantage of alkaline electrolysis technology over electrolysis with solid polymer electrolyte is the absence of platinum group metals in the composition of electrocatalysts. In addition, alkaline electrolyzers can operate at ambient temperatures below –40°C, while solid polymer electrolyzers irreversibly lose their performance at negative temperatures. This factor makes it possible to effectively use alkaline electrolysis at remote power facilities located in the Far North or on orbiting space stations. The energy efficiency of an electrolyzer is primarily determined by the properties of the diaphragm material [1, 2] and the electrocatalytic activity of the cathode and anode. There are known works on the use of nickel foam in alkaline electrolysis [3, 4], the surface of which is modified with the Ni–Co–S alloy or platinum [5]. In particular, in [6], red phosphorus was deposited on a metal foam (Ni–Fe) at a temperature of 600°C, but the authors note that such systems have insufficient stability, as a result of which the catalytic activity of electrodes significantly decreases after several tens of hours of operation.
Another direction in the development of highperformance electrodes is the formation of a porous nickel coating on the surface of a nickel mesh substrate by co-deposition of nickel and electrolytic nickel particles from a nickel plating bath containing a suspension of nickel powder. To further reduce the overvoltage of hydrogen and oxygen evolution, the porous nickel coating was modified with catalysts for cathodic processes Ni–Px and Ni–Mo, as well as catalysts for anodic processe
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