Boosting Activity and Stability of Metal Single-Atom Catalysts via Regulation of Coordination Number and Local Composition.

Controlling the chemical environments of the active metal atom including both coordination number (CN) and local composition (LC) is vital to achieve active and stable single-atom catalysts (SACs), but remains challenging. Here we synthesized a series of supported Pt1 SACs by depositing Pt atoms onto the pretuned anchoring sites on nitrogen-doped carbon using atomic layer deposition. In hydrogenation of para-chloronitrobenzene, the Pt1 SAC with a higher CN about four but less pyridinic nitrogen (Npyri) content exhibits a remarkably high activity along with superior recyclability compared to those with lower CNs and more Npyri. Theoretical calculations reveal that the four-coordinated Pt1 atoms with about 1 eV lower formation energy are more resistant to agglomerations than the three-coordinated ones. Composition-wise decrease of the Pt-Npyri bond upshifts gradually the Pt-5d center, and minimal one Pt-Npyri bond features a high-lying Pt-5d state that largely facilitates H2 dissociation, boosting hydrogenation activity remarkably.