Cu-based catalysts for electrocatalytic nitrate reduction to ammonia: fundamentals and recent advances

Electrocatalytic nitrate reduction has been identified as a promising technology for green ammonia production, allowing the conversion of harmful nitrate from wastewater into valuable ammonia using renewable electricity under ambient conditions. Developing advanced electrocatalysts is of paramount significance for improving the ammonia production efficiency in this process. Recently, Cu-based catalysts have been widely investigated in ammonia production via nitrate reduction due to their rapid reduction reaction kinetics, strong electrical conductivity, and ability to inhibit the hydrogen evolution reaction. Meanwhile, the reaction mechanism and computational and experimental methods have been extensively discussed to understand the theory behind the favourable properties of Cu-based catalysts. In this review, we focus on Cu-based catalysts, aiming to provide insights into the latest developments, reaction mechanisms, and state-of-the-art analysis methods for intermediates and products of nitrate reduction to ammonia. Future outlooks and remaining challenges are presented to provide guidance for advancing from experimental explorations to practical applications.