Nickel-Based Electrocatalysts for Hydrogen Production Through Hydrazine Electrolysis

Abstract

Hydrazine-coupled electrolysis (OHzS) offers an energy-efficient route for hydrogen production by replacing the sluggish oxygen evolution reaction (OER) with the faster hydrazine oxidation reaction (HzOR, E° = -0.33 V vs. RHE). This approach significantly lowers cell voltage and yields environmentally benign byproducts (N 2 and H 2 O), making it promising for green energy applications. However, the multistep proton-coupled electron transfer process in HzOR necessitates the development of highly active, stable, and cost-effective electrocatalysts.Nickel-based materials stand out due to their earth abundance, tunable Ni 2+ /Ni 3+ redox chemistry, excellent conductivity, and strong hydrazine affinity. This review summarises recent advances in Ni-based catalysts, including alloys, oxides, hydroxides, phosphides, nitrides, chalcogenides, and MOFs, emphasising synthesis strategies, hierarchical architectures, and key activity enhancement mechanisms such as synergistic effects, electronic structure modulation, defect engineering, and interfacial coupling. Insights from experiments and Density Functional Theory (DFT) calculations are discussed to elucidate reaction pathways and guide bifunctional catalyst design for concurrent HzOR and HER. Additionally, the integration of machine learning (ML) is highlighted as a promising approach to accelerate catalyst discovery and optimisation. We conclude with future directions toward scalable, high-performance, and low-voltage hydrogen generation by uniting mechanistic understanding, materials design, and predictive modelling.