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

Electrocatalytic NO2–-to-NH3 reduction (NO2RR) offers an attractive way to remedy polluted NO2– and produce value-added NH3. In this study, main-group Sn single atoms anchored on S-vacancy-rich MoS2–x (Sn1/MoS2–x) are explored as a highly selective NO2RR catalyst. Combined theoretical computations and in situ spectroscopic measurements reveal that the isolated Sn1 sites of Sn1/MoS2–x can not only promote NO2–-to-NH3 activation and hydrogenation but also favor NH3 desorption and restrict H adsorption, thus enabling a highly selective NO2RR for NH3 synthesis. Remarkably, Sn1/MoS2–x exhibits an NH3–Faradaic efficiency of 98.8% and an NH3 yield rate of 1922.3 μmol h–1 cm–2 in a flow cell, outperforming most of the NO2RR catalysts reported to date.