Controllable O2•− oxidization graphene in TiO2/graphene composite and its effect on photocatalytic hydrogen evolution

TiO2/reduced graphene oxide composite (T-rGO) was synthesized and its performance was evaluated with photocatalytic hydrogen evolution. It was found that the hydrogen evolution rate of T-rGO increased significantly after injecting small amount of air into the vacuum pumped and UV irradiated sealed reaction cell. The IR, XPS, Raman and ESR spectra analysis indicated that the O2•−, which generated from the reaction of photoinduced electrons and the injected O2 can moderately and controllably increase the oxygen groups on graphene planar of T-rGO at ambient condition. The amount of oxygen groups on graphene planar of T-rGO will affect the p-doping concentration of graphene, thus affect the p–n junction and the performance of T-rGO for photocatalytic hydrogen evolution.