Study on preparation of lead-free perovskite nanocrystals and their photocatalytic performances in carbon dioxide reduction
All-inorganic lead halide perovskites with excellent optoelectronic properties are ideal materials for photocatalytic carbon dioxide reduction.However,the toxicity and inherent instability of Pb limit their practical commercial application.To this end,lead-free perovskite materials Cs2PtBr6 microcrystal and Cs2PtBr6 nanocrystal were synthesized by anti-solvent method.The morphologies,compositions and optoelectronic properties of the samples were characterized by SEM,TEM,XRD and Ultraviolet-visible absorption spectrum,et al.The results show that the specific surface area of the sample is increased and the absorption performance is enhanced after Cs2PtBr6 microcrystal is converted into Cs2PtBr6 nanocrystal.The average photogenerated carrier lifetime is extended from 1.83 ns in Cs2PtBr6 microcrystal to 2.42 ns in Cs2PtBr6 nanocrystal.Moreover,the average photocurrent density of Cs2PtBr6 nanocrystal is 6.4 times stronger than that of Cs2PtBr6 microcrystal,and the charge transfer resistance of Cs2PtBr6 nanocrystal is smaller than corresponding value of Cs2PtBr6 microcrystal,so the separation and transfer efficiency of photogenerated carriers are improved.Among them,Cs2PtBr6 nanocrystal synthesized under 50℃of stirring temperature has the highest photocatalytic activity,and the carbon monoxide yield under the set up conditions of VCO2:VH2:VN2=21:63:16,total mass empty speed is 20000 mL/(g·h)and visible light irradiation for 3 h is 74.8 μmol/g,and the selectivity of carbon monoxide reaches 100%.These results can provide reference for the development of high-performance photocatalysts.
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