Synergistic Enhancement of Plasma‐Driven Ammonia Synthesis Using a AuCu₃/Cu Composite Catalyst

Abstract Green ammonia synthesis using fluctuating renewable energy supply in decentralized process is a goal that has been long sought after. Ammonia synthesis with non‐thermal plasma under mild conditions is a promising technology, but it faces the critical challenge of low energy efficiency. Herein, we develop an easily‐scalable AuCu 3 /Cu catalyst, which consists of a decimeter‐scale metallic Cu antenna and nano‐scale AuCu 3 catalytic sites on metallic Cu surface, significantly enhancing the energy efficiency and ammonia yield in a radio‐frequency (RF) plasma system. Compared to plasma alone, the single‐pass ammonia yield over AuCu 3 /Cu increases by a factor of 20, approaching 10 %. Mechanistic studies indicate that Cu antenna can amplify the millimeter‐scale local electric field, thereby facilitating the generation of active nitrogen species, including nitrogen radicals and vibration‐excited nitrogen molecules. Due to the downshifted d‐band center and unique Cu−Au interface structure, the AuCu 3 nanoalloy modified on Cu antenna surface significantly reduces hydrogenation barriers of active NH X ( x =0,1,2) species (the rate‐determining step) and facilitates ammonia desorption at lower temperature. The synergistic effect of Cu antenna and surface AuCu 3 nanoalloy comprehensively enhances ammonia synthesis through both the nitrogen radical‐mediated Eley‐Rideal pathway and the vibration‐excited nitrogen molecule‐mediated Langmuir–Hinshelwood pathway.