Enhanced Photocatalysis of Black TiO₂/Graphene Composites Synthesized by a Facile Sol-Gel Method Combined with Hydrogenation Process

In this study, in situ TiO₂ was grown on the surface of graphene by a facile sol-gel method to form black TiO₂/graphene composites with highly improved photocatalytic activity. The combination of graphene and TiO₂ was beneficial to eliminate the recombination of photogenerated electron holes. The self-doping Ti³⁺ was introduced, accompanied by the crystallization of amorphous TiO₂, during the hydrogenation process. Consequently, the narrowed bandgap caused by self-doping Ti³⁺ enhanced the visible light absorption and thus made the composites appear black. Both of them improved the photocatalytic performance of the synthesized black TiO₂/graphene composites. The band structure of the composite was analyzed by valence band XPS, revealing the reason for the high visible light catalytic performance of the composite. The results proved that the black TiO₂/graphene composites synthesized show attractive potential for applications in environmental and energy issues.