Manipulating a TiO₂-graphene-Ta₃N₅ heterojunction for efficient Z-scheme photocatalytic pure water splitting

Titanium dioxide (TiO₂)-based photocatalysts are a class of hottest materials in solar water splitting, while limited achievements have been gained to date due to its broad band-gap only responding in UV region and sluggish charge transfer. Here, we reported a ternary TiO₂-graphene-Ta₃N₅ hybrid photocatalyst synthesized via an ultrasonic-hydrothermal method. Compared with pristine TiO₂ and Ta₃N₅, the prepared TiO₂-graphene-Ta₃N₅ present remarkably enhanced photocatalytic pure water splitting behavior with an optimal H₂-evolution rate of 180 μmol h⁻¹ g⁻¹. In conjunction with systematic characterizations, we demonstrated the boosted photocatalytic performance is ascribed to both improved visible light utilization and charge transfer behavior. Particularly, it is found that water splitting is achieved through a Z-scheme mechanism, in which the two-dimensional lamellar graphene served as a bridge accelerating the electron transfer from TiO₂ to Ta₃N₅. This work opens avenues to design efficient TiO₂-based photocatalyst by embedding conducting layer for rapid electron transfer during solar-fuel conversion.