Mechanistic insights and rational catalyst design in NO _x electroreduction

The electrocatalytic reduction of nitrogen oxides (NO_x), particularly nitrate (NO₃^-), nitrite (NO₂^-) and nitrogen oxide (NO), to ammonia (NH₃) represents a sustainable strategy for nitrogen cycle management and pollution mitigation. However, optimizing the efficiency and selectivity for NH₃ production remains challenging because of competing side reactions, complex reaction networks, and the need for precise control over intermediate species. This review provides a comprehensive overview of recent theoretical advancements in the NO_x electroreduction reaction (NO_xRR), emphasizing mechanistic insights into reaction pathways, key intermediates, and activity-determining descriptors. We highlight the role of computational modeling, from density functional theory (DFT) studies and microkinetic simulations to machine learning-driven approaches, in elucidating active sites, guiding rational catalyst design, and accelerating material discovery. Special attention is given to the emerging synergy between theory and experiment, which bridges idealized models and realistic electrochemical conditions, thereby enabling data-driven catalyst discovery and mechanism-guided design. Finally, we outline the remaining challenges and future directions, emphasizing innovations in computational techniques and scalable catalyst development for sustainable ammonia synthesis and nitrogen waste reduction.