Ti3+ self-doped mesoporous black TiO2/graphene assemblies for unpredicted-high solar-driven photocatalytic hydrogen evolution.

Ti3+ self-doped mesoporous black TiO2/graphene assemblies are fabricated by a facile solvothermal method and surface hydrogenation. The structure, crystallinity, morphology, and chemical state of the as-prepared samples are characterized in detail by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, transmission electron microscopy, N2 adsorption and UV-visible diffuse reflectance spectroscopy. The results show that the presence of Ti3+ can efficiently extend the photoresponse of anatase TiO2 to visible light region. The solar-driven photocatalytic hydrogen evolution shows that Ti3+ self-doped mesoporous black TiO2/graphene assemblies exhibit the highest photocatalytic activity (186μmolh-1 0.01g-1), exceeding to mesoporous TiO2/graphene assemblies and mesoporous black TiO2. It also exhibits superior photoelectrochemical properties compared with mesoporous TiO2/graphene assemblies. The unpredicted-high photocatalytic performance is attributed to the close contact between the unique two-dimensional graphene structures coupled with TiO2 mesoporous architectures resulting in outstanding charge separation efficient and the Ti3+ self-doping extending the utilization ratio of visible light.