Plasma-Enabled Electrocatalytic Reduction of Nitrogen Oxides to Ammonia over Cu-N-P Catalysts

The electrocatalytic reduction of nitrogen oxides (NOx) to ammonia represents a promising alternative to direct N2 reduction but is often limited by low reaction rates, poor selectivity, and severe competition from hydrogen evolution under dilute feed conditions. Here, we report a plasma-enabled electrocatalytic strategy for efficient NOx-to-NH3 conversion using an electronically engineered Cu-N-P catalyst. A rotating gliding arc plasma converts air into reactive NOx species, providing a continuous and controllable feed for downstream electrochemical reduction. The Cu-N-P catalyst achieves an ammonia production rate of 2.36 mmol h−1 cm−2 with nearly 100% Faradaic efficiency at −0.575 V versus RHE and maintains stable operation for over 125 h under plasma-derived NOx conditions. Compared with unmodified Cu, the N, P co-doped catalyst promotes selective NOx adsorption and accelerates the hydrogenation of key intermediates while suppressing parasitic hydrogen evolution. Spectroscopic characterizations and theoretical analysis reveal that electronic structure modulation facilitates efficient NOx utilization and favorable hydrogenation kinetics. This work establishes an effective catalytic pathway for NOx-to-ammonia conversion under plasma-assisted conditions, providing insights into catalyst design for coupled plasma-electrochemical nitrogen conversion systems.