Direct Observation of Dynamic Bond Evolution in Single-Atom Pt/C3N4 Catalysts

Single-atom catalysts are promising platforms for heterogeneous catalysis, especially for clean energy conversion, storage, and utilization. Although great efforts have been made to examine the bonding and oxidation state of single-atom catalysts before and/or after catalytic reactions, when information about dynamic evolution is not sufficient, the underlying mechanisms are often overlooked. Herein, we report the direct observation of the charge transfer and bond evolution of a single-atom Pt/C3N4 catalyst in photocatalytic water splitting by synchronous illumination X-ray photoelectron spectroscopy. Specifically, under light excitation, we observed Pt-N bond cleavage to form a Pt-0 species and the corresponding C=N bond reconstruction; these features could not be detected on the metallic platinum-decorated C3N4 catalyst. As expected, H-2 production activity (14.7 mmol h(-1) g(-1)) was enhanced significantly with the single-atom Pt/C3N4 catalyst as compared to metallic Pt-C3N4 (0.74 mmol h(-1) g(-1)).