Preparation And Performance Of Visible Light Responsive TiO₂-based Photocatalytic Composites

With the improvement of living standard,people’s demand for consumer goods has gone beyond subsistence.However,the accompanying pollution from printing and dyeing wastewater has become increasingly severe.Therefore,cleaning printing and dyeing wastewater has become an important issue in the treatment of water pollution.Although TiO₂photocatalysts are easy to prepare and have high catalytic activity,the low utilization rate of visible light by TiO₂ monomer still needs improvement.Therefore,this thesis aims to enhance the photocatalytic activity of TiO₂ in visible light through elemental doping,crystal plane modulation and compounding with semiconductors,etc.The main research contents and results are as follows:Firstly,a fluorinated titanium dioxide precursor was prepared by a one-step hydrothermal method,and the precursor was calcined at high temperature in a nitrogen atmosphere to form a carbon dopant,and then a surface silver-deposited carbon/fluorine co-doped TiO₂photocatalyst C/F-Ag-TiO₂ was prepared by a hydrothermal method,and a comparison group of samples and C/F-Ag-TiO₂ deposited with different ratios of silver were tested for decomposition of Rhodamine B in visible light to The photocatalytic performance was evaluated.The results showed that the degradation rate of RhB under visible light was 84.2%at 4 h with a rate of 0.367 h^-1,which was 17 times higher than that of P25.Secondly,the exposed（001）surface titanium fluoride precursor was prepared by one-step hydrothermal method,and the fluoride titanium dioxide precursor was calcined at high temperature in air,and the silver-deposited boron/fluorine co-doped TiO₂ photocatalyst B/F-Ag-TiO₂ was prepared by two-step hydrothermal method with doping of boron elements and deposition of nano-silver,and the silver-deposited boron/fluorine co-doped TiO₂photocatalyst B/F-Ag-TiO₂ was prepared by testing the different ratios of doped samples and different ratios of silver-deposited samples under visible light The photocatalytic degradation of Rhodamine B by B/F-Ag-TiO₂ was evaluated by testing the photocatalytic degradation of Rhodamine B under visible light with different ratios of doping and silver deposited samples.The results showed that the material exhibited the highest catalytic performance with crystalline exposed titanium dioxide as the precursor,boron doping ratio of 7.5%and silver deposition ratio of 2%,and the degradation rate of RhB at 2 h reached 85.7%with a degradation rate of 0.808 h^-1,which was 7 times higher than that of fluorinated titanium dioxide precursor.The samples showed a performance loss of about 5%after six photocatalytic degradations,indicating that the composites have good photocatalytic stability.Lastly,the Ag-CuS-TiO₂ ternary composite photocatalysts were synthesized by depositing silver nanoparticles on the surface of the composites,and then the ternary Ag-CuS-TiO₂ composite photocatalysts were synthesized by testing the performance of different mass ratios of copper sulfide/titanium dioxide and different silver deposited samples.The photocatalytic performance was evaluated by testing the Ag-CuS-TiO₂ photocatalysts with different mass ratios of copper sulfide/titanium dioxide and different silver deposited samples for 2 h degradation of rhodamine under visible light.The results showed that the material exhibited the highest catalytic performance at 7.5%boron doping and 2%silver deposition,with 85%degradation of RhB at 2 h and a degradation rate of 0.735 h^-1,which was 9.5 times that of the copper sulfide precursor and 6.3 times that of the titanium dioxide precursor.The samples showed a performance loss of about 4.7%after six photocatalytic degradations,indicating that the composites have good photocatalytic stability.