Construction of electron donor–acceptor Z-scheme heterojunction for boosting photocatalytic H2 production

Abstract

Enhancing the solar energy conversion of metal-free graphitic carbon nitride (g-C3N4) based photocatalyst remains a great challenge. Herein, a novel Z-scheme heterojunction photocatalyst is constructed by in-situ anchoring Pt6 NCs on carbon self-doping g-C3N4 (CCN/Pt6 NCs) for boosting photocatalytic H2 evolution activity. Remarkably, the optimized CCN/Pt6 NCs photocatalyst exhibits high H2 evolution rate of 6.32 mmol·h−1·g−1 and 36.25 mmol·h−1·g−1, which is ≈150.5 and ≈412 times than that of pristine CN under visible light (λ > 420 nm) and full solar spectrum irradiation, respectively, outperforming majority of the reported g-C3N4-based photocatalysts. Systematic characterizations have revealed that CCN with delocalized electrons and larger the work function is deemed to be a preferable electron-acceptor. Meanwhile, Pt6 NCs with appropriate HOMO-LUMO level is regarded as an electron-donor. Theoretical and experimental works reveal that the favorable photocatalytic performance of CCN/Pt6 NCs heterojunction is mainly attributed to the giant internal electric field induced donor–acceptor interaction, which achieves Z-scheme charge transfer mechanism. This work opens up new insights for rational fabrication of metal-free g-C3N4 based photocatalysts to boost the solar energy conversion.