Anchoring Active Pt2+ /Pt0 Hybrid Nanodots on g-C3 N4 Nitrogen Vacancies for Photocatalytic H2 Evolution.

A Pt2+ /Pt0 hybrid nanodot-modified graphitic carbon nitride (CN) photocatalyst (CNV-P) was fabricated for the first time using a chemical reduction method, during which nitrogen vacancies in g-C3 N4 assist to stabilize Pt2+ species. It is elucidated that the coexistence of metallic Pt0 and Pt2+ species in the Pt nanodots loaded on g-C3 N4 results in superior photocatalytic H2 evolution performance with very low Pt loadings. The turnover frequencies (TOFs) are 265.91 and 116.38 h-1 for CNV-P-0.1 (0.1 wt % Pt) and CNV-P-0.5 (0.5 wt % Pt), respectively, which are much higher than for other g-C3 N4 -based photocatalysts with Pt co-catalyst reported previously. The excellent photocatalytic H2 evolution performance is a result of i) metallic Pt0 facilitating the electron transport and separation and Pt2+ species preventing the undesirable H2 backward reaction, ii) the strong interfacial contact between Pt2+ /Pt0 hybrid nanodots and nitrogen vacancies of CNV facilitating the interfacial electron transfer, and iii) the highly dispersed Pt2+ /Pt0 hybrid nanodots exposing more active sites for photocatalytic H2 evolution. Our findings are useful for the design of highly active semiconductor-based photocatalysts with extremely low precious metal content to reduce the catalyst cost while achieving good activity.