Recent Advances in Non-precious Metal-based Electrodes for Alkaline Water Electrolysis

Hydrogen gas has been regarded as an ideal energy source that could replace the need of fossil fuels, based on its high energy density with zero carbon emissions. The production of hydrogen via electrolysis of water is not a new field, but the technology has seen significant advancements in recent times, owing to the proportional growing demand of clean and affordable energy. This review discusses the most recent progresses achieved in the area of earth abundant catalysis, particularly, non-precious metal (Ni, Co, Fe, Mo, W)-based catalysts that are being utilized for the electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solutions. Based on the type of materials, the discussions are categorized into sections attributed to transition metal alloys, hydroxides, oxides, chalcogenides, carbides and nitrogenous materials. In general, a brief introduction of HER and OER mechanisms followed by a detailed discussion of the presently considered catalysts with endeavors have been made to highlight the new technologies and alternative approaches that are being considered promising towards production of clean H-2 energy. Finally, a prospective has been provided to accentuate the future of non-noble metal based catalyst in electro-catalytic water splitting reactions.