One‐step ammonia synthesis via a gas–liquid plasma‐electrocatalytic tandem reactor with effective proton utilization

Abstract The electrocatalytic N 2 reduction reaction (ENRR) for sustainable NH 3 synthesis remains constrained by the inertness of the NN bond and strong competition from the hydrogen evolution reaction. We present a gas–liquid plasma‐electrocatalytic tandem reactor that integrates non‐thermal plasma (NTP) activation of N 2 with efficient H2O‐derived proton utilization over a Cu catalyst, enabling one‐step NH 3 synthesis under ambient conditions. This system simultaneously dissociates N2 into active nitrogen components (ANCs) and optimizes atomic hydrogen (*H) adsorption in strong acid (pH ≤ 1). The synergistic NTP‐ERR process demonstrates a record NH 3 production rate of 150.2 μmol/h at ~20 mA/cm 2 —exceeding conventional ENRR by over 150‐fold and surpassing the sum of separate NTP and ERR processes. Mechanism studies indicate NH 3 forms mainly via direct coupling of ANCs with *H on Cu(111), with a secondary pathway involving NO x − reduction. The system's specific energy consumption (1161 kWh/kg NH 3 ) outperforms existing plasma‐assisted technologies. Compatible with renewable electricity, this strategy overcomes key limitations in nitrogen fixation and HER suppression, offering a practical route to decentralized ammonia production.