Preparation And Photocatalytic Properties Of Indium Oxide Based Porous Heterojunction

Porous semiconductor nanomaterials have been widely applied in field of catalysis,energy storage,gas sensor,Li-ion batteries and so on.Indium oxide（In₂O₃）is a typical n-type semiconductor with a band gap of 2.8 eV.In₂O₃ has received extensive interests in field of photocatalysis and gas sensors because of its ability to absorb visible light,low conductivity and excellent photochemical stability.However,the application of In₂O₃ still face the following problems in the field of photocatalysis.On the one hand,similar to other narrow bandgap photocatalysts,the photocatalytic activity of In₂O₃ is limited by the poor separation efficiency of the photogenerated electron-hole pairs.On the other hand,the small nano-size of In₂O₃ easily agglomerate together in the reaction solution,which will reduce the effective surface area,finally leading to a significant reduction in photocatalytic activity.In addition,the small nano-size of In₂O₃ is not easy to separate and recycle in the suspension system,which is not conducive to practical application.In order to solve the above problems,hierarchically porous In₂O₃/In₂S₃ heterostructures with abundant pores was synthesized by a distinctive polymer-assisted sol-gel freeze-drying method and subsequent simple self-sacrifice sulfidation processing.The specific research work is as follows:1.Hierarchically porous In₂O₃ with abundant micro-meso-macro pores was synthesized by a distinctive polymer-assisted sol-gel freeze-drying method combined with calcination process.By using a polymer polyethylene Polyvinylpyrrolidone（PVP）/indium nitrate（In₂（NO₃）₃）aqueous solution as a precursor,PVP/In₂（NO₃）₃ hybrid porous material is obtained by freeze-drying,and then calcined at high temperature to obtain porous In₂O₃.The porous structure of samples can be tailored by varying the polymer content.And,it was found that the presence of polymer played a decisive role in the formation and maintenance of the porous structure.To further study their potential,the photocatalytic degradation of the Rhodamine B（RhB）was investigated.The results showed that the enhanced photocatalytic performance of porous In₂O₃ is attributed to the presence of microporous and mesoporous provide high specific surface area and the three-dimensional open scaffolds could increase the light-harvesting and facilitate mass transport of reactants.2.By using the obtained porous In₂O₃ as a hard and L-cysteine as a sulfur source,the hierarchically porous In₂O₃/In₂S₃ heterostructures were prepared by simple elf-sacrifice sulfidation processing.The influence of the relative content of In₂S₃ on the photocatalytic properties of In₂O₃/In₂S₃ heterostructures was investigated.The results indicated that the enhanced photocatalytic performance is attributed to the synergy of photogenerated electron-hole pairs for effective separation,high specific surface area,increased light-harvesting and facilitate mass transport of reactants.In addition,the large size self-supported structure makes it unnecessary to separate the samples during the photocatalytic reaction which is conducive to recovery and recycling.