| Among various oxide semiconductor photocatalysts,TiO2 photocatalysts have been proved to be the most suitable materials due to their non-toxicity,stable properties,strong redox properties,chemical corrosion resistance and photo-corrosion ability,and were widely used in the environment field.However,there are two factors that restrict the industrial application of TiO2 photocatalyst.In the degradation process,photogenerated electrons and holes are easy to recombine due to the slow degradation rate;it exhibits catalytic activity?lower utilization of visible light?only under ultraviolet light,making it limited in practical applications.In order to solve the above problems,the key is design synthetically porous carbon-supported nano-TiO2 to improve photocatalytic performance.The thesis focuses on the preparation of porous carbon-supported nano-TiO2 and its doping modification.1?In the second chapter of this paper,a series of mesoporous photocatalysts(Ag/TiO2-x/C composites)with high porosity were prepared by silver ion modification with Zn-Ti metal organic framework materials at different temperatures,and its photocatalytic activity was evaluated by photodegradation behavior of methylene blue solution?MB?under ultraviolet light.At 1000°C,Ag/TiO2-x/C composites have the best photocatalytic performance.Under the irradiation of 300 W power Xenon lamp,the degradation rate of MB with concentration of 20 mg/L can reach 99.4%within 50 min,and the rate of degradation of MB was 8.33 times that of P25?commercial TiO2?.It is found that due to the high oxygen vacancy density of silver modification and TiO2-x lattice,it is better to capture electrons better,and the specific surface area of the catalyst is higher due to the reduction and evaporation of metallic zinc.Under the same experimental conditions,no significant inactivation was observed after MB was degraded.2?In the third chapter of this paper,a Zn-Ti metal organic framework material precursor was synthesized by hydrothermal method as a template,and platinum ion doping modification was introduced,then,a series of mesoporous nanocomposites(Pt/TiO2-x/C composites)with higher specific surface area were obtained by sintering at different temperatures.The photocatalytic effect of these catalysts was studied by using 300 W power xenon lamp to simulate the measurement of sunlight by methylene blue as a representative organic pollutant.Among them,When the sintering temperature of 1000??PTC-P10?showed excellent photocatalytic effect,the degradation rate of MB with concentration of 20mg/L can reach 98%within 20 min,and the rate of degradation of MB was 8.69 times that of P25?commercial TiO2?and 1.04 times that of ATC-P10?Ag/TiO2-x/C composites?.It is found that due to the doping of platinum,the forbidden band width of the photocatalyst becomes smaller,and a new impurity level is formed in the forbidden band,so that photons with smaller energy can also be trapped at the excitation impurity level.The absorption band of the catalyst is red-shifted,which expands the spectral response range and improves the utilization of light.At the same time,Pt4+will enter the TiO2-x lattice to replace Ti4+,causing lattice defects,which will generate more oxygen vacancies to capture electrons,and make photoelectron-hole pairs more difficult to recombine.Therefore,the Pt/TiO2-x/C composite has higher solar utilization than the Ag/TiO2-x/C composite,which can improve the excitation efficiency of photogenerated electrons and make the photogenerated electron-hole pairs more difficult to recombine.Under the same experimental conditions,no significant inactivation was observed after MB was degraded.Compared with Ag/TiO2-x/C composite catalyst,the catalyst is a more stable and efficient photocatalyst that can be recycled. |
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