Ammonia electrosynthesis on carbon-supported metal single-atom catalysts

Ammonia, a feedstock platform for fertilizer and pharmaceutical production, is regarded as a zero-carbon energy carrier. The electrochemical synthesis of ammonia, powered by clean and renewable electricity, has garnered increased attention as an alternative to the Haber-Bosch process. Very recently, single-atom catalysts (SACs) have become highly effective electrocatalysts for such electrochemical transformation, where the isolated metal sites ensure the high atomic utilization efficiency as well as the prevention of nitrogen-nitrogen coupling. In this review, we focus on the recent progress of single-atom catalysts in electrochemical ammonia synthesis and briefly introduce nitrogen cycles in both natural and artificial ecosystems, followed by a discussion of catalyst design by theoretical and experimental methods. Synthesis routes from different nitrogen sources, including dinitrogen (N2) and nitrogen oxides (NOx), are also highlighted. Besides, the catalysis dynamics as an indispensable section is presented and discussed in-depth. Finally, we tackle challenges and offer perspectives, aspiring to provide insightful guidance for researchers in this community striving for advanced ammonia electrosynthesis.