Constructing Z-scheme between graphite nitride carbon and supramolecular zinc porphyrin to promote photocatalytic H₂ evolution

The separation and transport of charge carriers between heterojunction interfaces are key factors that constrain their photocatalytic activity. In current study, a new binary heterojunction (BCN-N-SA) composed of g-C₃N₄ nanosheet (BCN-N) and self-assembled supramolecular zinc porphyrin (SA-ZnTCPP) was successfully synthesized for photocatalytic hydrogen evolution (PHE) from water splitting. The optimal PHE rate of BCN-N-SA reaches 23.895 mmol g⁻¹ h⁻¹, which is 38.05, 6.93 and 6.75 times higher than that of unassembled ZnTCPP, SA-ZnTCPP and BCN-N, respectively. It is revealed that a Z-scheme mechanism between BCN-N and SA-ZnTCPP has been constructed in BCN-N-SA, which efficiently promotes the separation and transport of photogenerated charge carriers, thereby greatly improving the PHE efficiency. This work indicates that constructing the Z-scheme mechanism through band regulation is an effective method to improve the PHE efficiency.