Electrochemical reduction of nitrate to ammonia using non-precious metal-based catalysts

Nitrate pollution is becoming more prevalent and posing serious threats to both human living and the envi-ronment. Electrochemical reduction is an eco-friendly technique with high energy efficiency to remove nitrate compounds from wastewater while producing ammonia as a value-adding product. However, owing to the complex reactions and limited selectivity, a good understanding of the mechanisms is crucial to further devel-opment and commercialization. Recently, transition-metal electrocatalysts boasting virtues such as natural abundance, high activity, and cost-effectiveness are garnering increasing interest in the aspect of nitrate reduction. Herein, recent developments of non-precious transition metal-based catalysts in electrochemical ni-trate reduction and the pertinent mechanisms are described. In addition to the important techniques, future challenges and prospects are discussed to guide future research on non-precious metal catalysts for commercial NH3 synthesis by NO3- reduction.