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

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.