Lin, J.Wang, Y.Tian, W.Zhang, H.Sun, H.Wang, S.2023-09-182023-09-182023ACS Catalysis, 2023; 13(17):11711-117222155-54352155-5435https://hdl.handle.net/2440/139501Ammonia (NH3) splitting to hydrogen (H2) is a promising route for on-site production of green hydrogen energy; however, the application is limited due to high-cost noblemetal-based catalysts and high operating temperature of the endothermic nature. Herein, we develop a series of macroporous carbon nitride-supported single-atom transition metal (TMsMCN, TMs: Co, Mn, Fe, Ni, Cu) catalyst panels for solar light-driven photocatalytic gaseous NH3 splitting. Under ambient reaction conditions, the optimized Ni-MCN shows an H2 production rate of 35.6 μmol g−1 h−1 , much superior to that of MCN and other TMs-MCN. Such enhanced photoactivity is attributed to the presence of Ni−N4 sites, which improve the optical properties, accelerate charge carrier separation/ transfer, and boost NH3 splitting kinetics of the catalysts. Density functional theory calculations further reveal that the Ni−N4 sites can effectively modify the electronic structure of the carbon nitride. Compared with other metal sites, the Ni−N4 site possesses moderate NH3 binding strength and the lowest energy barrier to facilitate the formation of key intermediates *NH + *H. These findings provide valuable guidelines for the rational design of single-atom catalysts toward energy- and cost-effective photocatalytic NH3 splitting for H2 production.en© 2023 American Chemical Societyambient ammonia splittingammonia to hydrogencatalyst panelsingle-atom photocatalysisstructure−activity relationshipJournal article10.1021/acscatal.3c020762023-09-18654489Lin, J. [0000-0001-6409-0146]Tian, W. [0000-0002-7503-5481] [0000-0002-9896-1154]Wang, S. [0000-0002-1751-9162]