Preparation Of Titanium Dioxide Nanomaterials By Noble Metals Modified/Graphene Composite And Its Photocatalytic Properties

Semiconductor photocatalysis technology is one of the effective ways to use solar energy efficiently and to control environmental pollution.Because titanium dioxide has the advantages of chemical stability,low toxicity and high photocatalytic redox ability,it has become the most widely studied semiconductor photocatalytic material.However,the titanium dioxide material also has problems such as response in the ultraviolet light range,rapid photoreaction of photogenerated electrons in the photodegradation process,and small specific surface area.Based on the limitations of titanium dioxide photocatalyst,the key factors to improve performance and the breakthrough of new materials,this paper mainly improves the photocatalytic performance of titanium dioxide from the following aspects:?1?Graphene oxide?GO?was prepared by the modified Hummers method using natural flake graphite as raw material,concentrated sulfuric acid,concentrated nitric acid and potassium permanganate as intercalation oxidants.Using tetrabutyl titanate?Ti?OBu?₄?as the titanium source,silver was modified in the titanium dioxide nanowire by high-voltage electrospinning,the reduced graphite oxide?rGO?is composited on the silver-modified titanium dioxide nanowire by a secondary hydrothermal method.Preparation of heterogeneous Ag-TiO₂-rGO composite,the photocatalytic activity of the prepared TiO₂,Ag-TiO₂ and Ag-TiO₂-rGO nanowires was evaluated by using 20 mg·L^-11 Rhodamine B?RhB?solution as the simulated degradation pollutant.The results show that Ag-TiO₂-rGO has the best photocatalytic activity and can degrade 92.9%of 20 mg·L^-11 Rhodamine B?RhB?in 80 min.?2?Silver-modified titanium dioxide nanospheres composite reduced graphite oxide?rGO?composites were prepared by two-step hydrothermal method.Preparation of Ag-TiO₂ nanomaterials with silver loadings of 1%,2%and 3%,respectively,after SEM,TEM and XRD characterization,and photodegradation of rhodamine B?RhB?,2%Ag-TiO₂ showed the best photodegradation performance.After combining 2%Ag-TiO₂ with reduced graphene oxide?rGO?,2%Ag-TiO₂-rGO can degrade 96.0%of10 mg·L^-11 of Rhodamine B?RhB?in 100 min.?3?Titanium sulphate?Ti?SO₄?₂?is used as the titanium source,and ammonium fluoride?NH₄F?is used as the morphology control agent.The hierarchical titanium dioxide hollow microspheres with high energy{001}crystal planes were prepared by hydrothermal method at a reaction temperature of 180°C and a reaction time of 10 h.Secondary hydrothermal recombination of reduced graphene oxide?rGO?on the surface of the hollow microspheres.The nanometer microsphere structure of titanium dioxide is obtained by replacing the crystal plane regulator ammonium fluoride?NH₄F?with urea.The results of the comparative study show that:Degradation of15mg·L^-11 Rhodamine B?RhB?solution in 90 min,the degradation rate of titanium dioxide in solid microsphere structure was 65.73%,and the degradation rate of hollow titanium dioxide microspheres exposed to{001}crystal surface reached 90.08%.