Main-Group Sn Single Atoms on MoS2–x for Selective Nitrite Electroreduction to Ammonia

Electrocatalytic NO 2 – -to-NH 3 reduction (NO 2 RR) offers an attractive way to remedy polluted NO 2 – and produce value-added NH 3 . In this study, main-group Sn single atoms anchored on S-vacancy-rich MoS 2– x (Sn 1 /MoS 2– x ) are explored as a highly selective NO 2 RR catalyst. Combined theoretical computations and in situ spectroscopic measurements reveal that the isolated Sn 1 sites of Sn 1 /MoS 2– x can not only promote NO 2 – -to-NH 3 activation and hydrogenation but also favor NH 3 desorption and restrict H adsorption, thus enabling a highly selective NO 2 RR for NH 3 synthesis. Remarkably, Sn 1 /MoS 2– x exhibits an NH 3 –Faradaic efficiency of 98.8% and an NH 3 yield rate of 1922.3 μmol h –1 cm –2 in a flow cell, outperforming most of the NO 2 RR catalysts reported to date.