Relationships among structure, composition, and selectivity in the electrocatalytic reduction of nitrate ions

Electrochemical nitrate reduction reaction (NO₃RR) is crucial in converting wastewater nitrate sources into value-added products under mild, low-cost conditions. Metals with highly occupied d-orbitals, such as Au, Ag, Cu, and Pt, are promising materials for high-performance electrocatalytic NO₃^- reduction due to their favorable surface electronic properties. While many metals are effective catalysts for NO₃RR, their limited ability to favor specific products often hinders practical application. This short review analyzes recent understanding of the reaction mechanisms and pathways of NO₃RR, focusing on the structural and electronic effects of the catalysts such as underpotential deposition systems and single-atom catalysts on product selectivity.