Preparation And Photocatalytic Properties Of Ti 3+ Self-doped Mesoporous Black TiO 2 And Its Composites

Mesoporous TiO₂ is widely used in fields of photocatalysis,photoelectrocatalysis,and solar cells,because of the well-developed porous structure,large specific surface area,high porosity and narrow pore size distribution.However,the conventional mesoporous TiO₂ can only absorb ultraviolet light due to its wide bandgap?3.2 eV?,and the utilization of sunlight is limited.In order to broaden the light 'absorption range,we use surface hydrogenation strategy to synthesize Ti³⁺ self-doped mesoporous black TiO₂ materials.The mesoporous skeleton was protected by coating ethylenediamine to make the mesoporous networks against collapsing during in the high temperature hydrogenation process,while maintaining the crystal phase unchanged.The narrow band gap can make the absorption range extended to visible light region.Acting it as a host material,Ti³⁺ self-doped mesoporous black TiO₂ composite materials were constructed to further improve the photocatalytic performance.This paper is divided into the following three parts:1.A high thermal stability mesoporous TiO₂ microspheres was synthesized by solvent evaporation-induced self-assembly method,and then combined with ethylenediamine to protect the mesoporous structure.Ti³⁺ self-doped mesoporous black TiO₂ microspheres were obtained by surface hydrogenation.The as-prepared sample had high specific surface area,narrow band gap??3 eV?,and the light absorption range extended to visible light region.Under the simulated sunlight?AM 1.5?irradiation,the photocatalytic hydrogen production was up to 486 ?mol h-1,which was due to Ti³⁺ self-doping to broaden the range of light absorption and improve the separation efficiency of photogenerated charge carriers.2.Ti³⁺ self-doped mesoporous black TiO₂ microspheres as the host materials,the mesoporous black TiO₂/Ag composite material was synthesized by ultrasonic impregnation and hydrogen reduction method.The absorption and utilization of visible light is further enhanced by the surface plasmon resonance effect of noble metal Ag.Under the simulated sunlight?AM 1.5?irradiation,the photocatalytic hydrogen production was up to 616?mol h-1,and the photocatalytic performance was significantly improved.3.Ti³⁺ self-doping black TiO₂ nanothorn/graphene/black TiO₂ nanothorn sandwich-like structure composite was prepared by solvothermal combing with surface hydrogenation strategy.Ti³⁺ self-doped black TiO₂ nanothorns were grown on both sides of graphene and the sandwich-like architecture was formed finally.The band gap was reduced to?2.8 eV and the introduction of graphene could promote the separation and transport of photogenerated charge carriers,which significantly improved the photocatalytic performance.This novel composite will have potential application values in photocatalytic field.