▎ 摘　　要

Cs-decorated reduced graphene oxide (CsRGO) was synthesized by addition of a CsOH solution to a GO suspension. The resulting material is amorphous, while GO reduces upon Cs incorporation as Cs2O-like clusters. Structure modelling indicates that Cs atom replaces hydrogen in hydroxyl and carboxyl groups in the graphene plane. CsRGO exhibits transitions associated to the pi-to-pi*, remanent C=O groups and Cs2O absorption. The material is n-type semiconductor, with a direct optical band gap of 2.85 eV. Carrier injection from the Cs2O to RGO enhances H-2-evolution. Stable photocatalytic generation of hydrogen after three four-hour cycles, is attributed to work function reduction, high conductivity, and high optical absorption upon Cs-incorporation.