Confining nitrogen nanobubbles within plasma etched voids to promote reactant supply for enhanced electrochemical nitrogen reduction reaction under ambient conditions

The electrocatalytic nitrogen reduction reaction (NRR) holds great potential for green ammonia synthesis and has aroused interest of the scientific community. However, the restricted nitrogen supply at the reaction interface has always been the major unresolved issue, leaving the actual performance much to be desired. Herein, a nitrogen confining strategy achieved by plasma etching is proposed to address this challenge. A large number of voids can be in situ constructed in the basal plane of the catalyst upon plasma etching. The void-like defects would induce surface heterogeneity and effectively enhance the van der Waals interactions between the electrocatalyst and the nitrogen molecules, triggering directional nitrogen transfer toward the catalyst. The oncoming nitrogen nanobubbles can be effectively captured by the voids, providing abundant reactant supply and thus boosting the whole NRR process. As expected, the atomically dispersed metal-nitrogen-carbon catalyst with optimized plasma etching treatment delivers a superior ammonia yield rate of 35.24 μg h−1 mg−1 and an outstanding Faradaic efficiency of 53.99 % at −0.3 V versus reversible hydrogen electrode. This work underscores the importance of abundant reactant supply and presents a versatile strategy for enhancing the overall performance of gas-involved electrochemical reactions.