Recent advances in nickel-based catalysts for electrochemical nitrate reduction to ammonia

The electrocatalytic nitrate reduction to ammonia (NRA) has emerged as a promising alternative to the traditional Haber-Bosch process owing to its environmental friendliness and high efficiency. However, the widespread application of NRA is still hampered by the sluggish reaction kinetics, uncontrollable selectivity, and limited electron donor availability. Notably, NRA electrode materials exert a critical influence on NRA performance. Nickel-based materials, characterized by low cost, high activity, and adaptable electronic structure, are considered as an ideal candidate. This review first provides an overview of electrocatalytic pathway and mechanism for NRA. Subsequently, the recent advances in nickel-based catalysts for NRA are discussed in terms of mono-metallic, bimetallic, alloy and phosphide materials, with particular focus on their structure–property relationship, preferred pathway and innovative construction strategies. The influencing factors including support effect, synthesis method, initial nitrate concentration and pH value are explored with relevant catalysts. The review concludes with the challenges and future perspective of nickel-based materials with high NRA performance for potential practical applications.