▎ 摘　　要

Graphene as an electron-conductive medium has been widely used to construct efficient photocatalysts for solar energy conversion, while the discovery of photosensitizer role of graphene further enriches our understanding of the multifunctional facets of graphene in graphene-based composite photocatalysis. However, the photosensitive efficiency of graphene remains relatively low, and the photosensitization mechanism has yet to be elucidated. Herein, we report a facile wet chemistry strategy to enhance the photosensitive efficiency of graphene via oxidation treatment of graphene oxide and particularly reveal the underlying origin of such boosted photosensitive efficiency of graphene. Graphene derived from graphene oxide with enhanced oxidation degree shows remarkably improved photosensitive efficiency for wide-bandgap ZnO toward visible-light-driven photoreduction process. Controlled experiments disclose that the residual content of oxygenated functional groups is the main factor affecting the photosensitive efficiency of graphene. Furthermore, theoretical calculations indicate that increasing the content of oxygenated functional groups in graphene is able to widen the bandgap of graphene with the upshift of its conduction band, which endows the electrons in the photocatalytic system with enhanced reduction capacity and thus boosts the photosensitive efficiency of graphene. These encouraging results would provide instructive guidelines for the utilization of multifunctional roles of graphene toward designing advanced graphene-based composite photocatalysts for solar energy conversion.