Nitrate Electroreduction to Ammonia Over Copper-based Catalysts

The electrocatalytic reduction of nitrate (NO₃ ^-) to ammonia (NH₃) holds substantial promise, as it transforms NO₃ ^- from polluted water into valuable NH₃. However, the reaction is limited by sluggish kinetics and low NH₃ selectivity. Cu-based catalysts with unique electronic structures demonstrate rapid NO₃ ^- to NO₂ ^- rate-determining step (RDS) and fast electrocatalytic nitrate reduction reaction (eNO₃RR) kinetics among non-noble metal catalysts. Nonetheless, achieving high robustness and selectivity for NH₃ with Cu-based catalysts remains a significant challenge. This review provides a comprehensive overview of the reaction mechanisms in eNO₃RR, highlights how the structures of monometallic and bimetallic Cu-based catalyst affect catalytic properties, and discusses the current challenges as well as prospects in eNO₃RR.