Review and Perspective of Nickel and Its Derived Catalysts for Different Electrochemical Synthesis Reactions in Alkaline Media for Hydrogen Production

Hydrogen (H2) is a promising alternative energy source, but its current production method through steam reforming is energy intensive and polluting. Water electrolysis, specifically the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), offers a cleaner option. Although HER is the favorable process, OER needs a larger overpotential, thereby hindering practical implementation. The use of expensive noble metal-based catalysts limits the application. The levelized cost of hydrogen can be lowered by replacing the anodic reaction with several innovative strategies. Alternative oxidation reactions have emerged as some of the most noteworthy new strategies. A critical analysis of electrochemical synthesis reactions (ESR) combining anodic chemical synthesis and cathodic hydrogen evolution is presented here for replacing the traditional OER with organic molecule oxidation. This review aims to explore nickel and nickel-based catalysts for different ESR reactions, such as alcohol, aldehydes, amines, and biomass-derived compounds, for energy-efficient and cost-effective electrocatalytic hydrogen production. In this critical review, we present a clear picture of the challenges and bottlenecks associated with electrochemical synthesis reactions as a method of industrial hydrogen production needs. Finally, a perspective and challenges for future development of the hybrid water electrolysis techniques are demonstrated.