ELECTROCATALYTIC PROBLEMS IN WATER ELECTROLYSIS

Electrocatalysts on the basis of nickel and nickel alloys can be considered as materials for nonconsumable electrodes in alkaline solutions including those used in large-scale hydrogen production in advanced water electrolyzers. It was found to be possible as a result of nickel catalyst studies accomplished during the last 10-15 years to provide a unified analysis of the properties of massive and highly disperse nickel such as the surface state, the adsorption of hydrogen, oxygen, and organic substances, and the specific catalytic activity, reveal mechanistic details of the electrode processes, describe the properties of highly disperse catalysts, the structure of the catalytic layers, and the mechanism of gas formation in porous media. These investigations led to a better understanding of the complex processes occurring in systems for water electrolysis and to new suggestions for improved electrolyzers by activation of the electrodes, a more compact cell design, and optimized electrolyzer operating conditions. These aspects are discussed in the present review.