▎ 摘　　要

Nitrogen-doped graphene oxide quantum dots exhibit both p- and n-type conductivities and catalyze overall water-splitting under visible-light irradiation. The quantum dots contain p-n type photochemical diodes, in which the carbon sp(2) clusters serve as the interfacial junction. The active sites for H-2 and O-2 evolution are the p- and n-domains, respectively, and the reaction mimics biological photosynthesis