| Photocatalytic technology is clean and pollution-free,and is considered to be one of the best solutions to alleviate the problems of energy depletion and environmental pollution.All-inorganic CsPbBr3（CPB）perovskite quantum dots（QDs）have attracted more and more attention in the field of photocatalysis due to their excellent photoelectric conversion performance,but there are still problems such as insufficient environmental stability and low utilization of light energy.In view of these problems of CPB,this thesis attempts to modify them by wrapping Ti O2 and constructing the composite with metal-organic frameworks（MOFs）（i.e.,NH2-MIL-125（NMT））,which improves the spectral responsiveness and structural stability of CPB and thus enhances the photocatalytic activities of CPB.The research contents mainly include as follows:（1）The CPB QDs were firstly synthesized by the ligand-assisted precipitation method,and then Ti Ox was nucleated and grown on the surface of CPB by adding 1-butanol titanium（TBOT）precursor to toluene solution with dispersed CPB QDs.The content of Ti Ox could be changed by regulating the amount of TBOT,and then the CPB/Ti O2 composite catalyst with high-stability could be prepared by subsequent high-temperature calcination.The research results show that the Ti O2 shell layer could effectively improve the water stability of CPB and perform photocatalytic degradation of organic pollutants in aqueous solution.The heterojunction formed between CPB and Ti O2 could effectively prevent the recombination of photogenerated electron and hole pairs,accelerate the migration of photogenerated carriers in CPB/Ti O2,and thus enhance the photocatalytic reaction.Finally,the CPB/Ti O2 composite catalyst with the appropriate ratio of CPB and Ti O2 could completely degrade Rhodamine B（Rh B）within 100 min in water environment,and the degradation rate constant could reach357×10-4 min-1.（2）The NMT material was firstly synthesized by the hydrothermal method,and then the prepared NMT was uniformly dispersed into the precursor solution of CPB QDs.The CPB QDs were loaded on the NMT surface by the thermal injection method,and the NMT/CPB composite photocatalyst was thus obtained.The research results show that the NMT/CPB composite can effectively combine the advantages of both CPB and NMT.On the one hand,the framework structure of NMT could effectively increase the catalytic reaction area and provide more active sites.On the other hand,CPB QDs could play the characteristics of high optical absorption coefficient and long carrier diffusion length as electron donors.According the performance of photocatalytic CO2 reduction,the NMT/CPB heterostructured catalyst performed well in the evaluation of CO2 reduction to CO and CH4,among which the yields of CO and CH4 for the best performing sample were 4.76μmol g-1 h-1 and 0.14μmol g-1 h-1respectively and the selectivity of CO was up to 89.47%.Meanwhile,the average electron consumption was 10.64μmol g-1 h-1,which was 3 times and 4.8 times that of CPB and NMT,respectively. |
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