Preparation Of Defective TiO_2-x With Graphene Composite Structure And Study On Their Photoelectrocatalytic Performance

With the rapid development of economy and the continuous growth of population,energy crisis and environmental pollution have been triggered.Photocatalytic technology has become one of the important methods to solve energy and environmental problems due to its advantages of utilizing solar energy and being clean and environmentally friendly.As a traditional photocatalyst,TiO₂ is widely used in fields such as photocatalytic degradation of pollutants and photolysis of water.However,TiO₂ only absorbs ultraviolet light and possesses low quantum efficiency,which limits its further application.Among various TiO₂ modification strategies,black TiO₂ has attracted the attention of researchers due to its unique structural properties and enhanced solar absorption ability.However,black TiO₂ did not fully address the issues of carrier recombination and low visible light catalytic activity.Graphene is a kind of carbon material with unique structure and excellent electrical conductivity,which can effectively improve the electron transport rate.Therefore,this article prepared defective（black） TiO_2-x with graphene composite structure,which effectively promoted the separation of electron hole pairs and improved visible light catalytic activity in a photoelectric synergistic system.The main research contents were presented as follows:1.Black-TiO_2-x/G catalyst was synthesized by solid-state dispersion method and Na BH₄ thermal reduction method with TiO₂ reactant.Disordered amorphous shells appear on the surface of Black-TiO_2-x crystals.Oxygen vacancy and Ti³⁺ defect formed impurity level between CB and VB of TiO_2-x,which effectively improved the visible light absorption performance.The loading of graphene further improved the efficiency of carrier separation and enhanced visible light catalytic activity.The conditional experiment showed that the optimal photocatalytic performance was achieved when the NaBH₄:TiO₂ mass ratio was 3:8 and the graphene loading was 1wt%.Under the conditions of visible light（λ＞400nm）and applied 1V bias,Black-TiO_2-x/G exhibited a significant photoelectric synergistic effect,achieving a photocatalytic degradation rate of 91.0% for RhB within 180 minutes.2.N@TiO_2-x/G catalyst was synthesized by in-situ hydrothermal synthesis assisted by H₂O₂ solution with TiN precursor.It was found that the addition of H₂O₂ promoted the formation of Ti-O bonds and other oxygen-containing species.Partial oxidation method also preserves a fewer Ti³⁺ defects in TiN precursors and promotes the formation of oxygen vacancies,while the graphene loading promotes the effective separation of photogenerated electrons from holes.The experiment showed that both H₂O₂and graphene were added in moderate amounts,and the catalyst with 15ml 30% H₂O₂ solution and 1wt% graphene had the best performance.N@TiO_2-x/G showed obvious photoelectric synergistic effect,the photoelectro-catalytic degradation rate reached 88.0% within 180min.In addition,the catalyst showed the certain stability and reproducibility.The experimental results showed that the defective TiO_2-x with graphene composite structure possessed obvious photoelectrocatalytic activity and showed certain application value in the field of photocatalytic degradation of pollutants.