Anchoring Active Pt2+/Pt0 Hybrid Nanodots on g-C3N4 Nitrogen Vacancies for Photocatalytic H2 Evolution

A Pt2+/Pt-0 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-C3N4 assist to stabilize Pt2+ species. It is elucidated that the coexistence of metallic Pt-0 and Pt2+ species in the Pt nanodots loaded on g-C3N4 results in superior photocatalytic H-2 evolution performance with very low Pt loadings. The turnover frequencies (TOFs) are 265.91 and 116.38h(-1) for CNV-P-0.1 (0.1wt% Pt) and CNV-P-0.5 (0.5wt% Pt), respectively, which are much higher than for other g-C3N4-based photocatalysts with Pt co-catalyst reported previously. The excellent photocatalytic H-2 evolution performance is a result of i)metallic Pt-0 facilitating the electron transport and separation and Pt2+ species preventing the undesirable H-2 backward reaction, ii)the strong interfacial contact between Pt2+/Pt-0 hybrid nanodots and nitrogen vacancies of CNV facilitating the interfacial electron transfer, and iii)the highly dispersed Pt2+/Pt-0 hybrid nanodots exposing more active sites for photocatalytic H-2 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.