Recent Breakthroughs in Electrocatalytic Reduction of Nitrogen-Oxyanions for Environmentally Benign Ammonia Synthesis

Ammonia (NH₃) synthesis using nitrogen-oxyanions (NO_x⁻, such as NO₃⁻ and NO₂⁻) as source materials powered by renewable electricity under ambient conditions provide a promising route to realize artificial nitrogen recycling and mitigate environmental pollution. Despite numerous reports showcasing a Faraday efficiency (FE_NH3) of approximately 90% for electrochemical NO_x⁻ reduction to NH₃ under specific conditions, the rational design of highly efficient electrocatalysts that can withstand future demanding industrial testing conditions remains a persistent challenge. In this review, we introduce and delve into the prevalent theories and mechanisms of electrochemical NO_x⁻ reduction for NH₃ synthesis, aiming to provide guidance for the design of catalysts. Subsequently, we present recent ground-breaking efforts in the realm of electrochemical NH₃ synthesis via NO_x⁻ reduction reaction (NO_x⁻RR), engaging in a discourse centred on the design of diverse electrocatalysts. Furthermore, a summary and analysis of the potential commercial feasibility of electrocataltyic NO_x⁻ reduction for NH₃ synthesis have been conducted, with the goal of providing valuable insights and references for the subsequent large-scale development and application of this technology. Finally, the remaining challenges and prospects in this field have been highlighted. This review provides a comprehensive understanding of electrochemical NO_x⁻ reduction for NH₃ synthesis, setting the stage for future innovations in efficient, large-scale electrochemical NH₃ production technologies.