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

Abstract

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.