Preparation And Photocatalytic Application Of Niobium Pentoxide Nanostructure

Niobium pentoxide is typical N-type semiconductor with band gap of 3.4-4.0 eV.Nb₂O₅is not only relatively abundant in nature,but thermodynamically,mechanically and chemically stable,much more corrosion-resistive than TiO₂.One dimensional nanostructure exhibits superior photonic and electronic property comparing with bulk phase resulting from the high specific surface and quantum confinement effect.So far,electrospinning and thermal oxidation of niobium foil are the main strategies to prepare one dimensional niobium pentoxide nanostructure,but they are both energy-consuming and high cost regarding its raw materials and equipment.In all,the study of one dimensional niobium pentoxide is at the primary stage,its morphology is comparatively incomplete.In this thesis,we explored hydrothermal,solvothermal and molten-salt methods to prepare single-crystal one dimensional niobium pentoxide nanostructure.As a result,we prepared three different morphology one dimensional niobium pentoxide nanostructures:niobium pentoxide nanowires with a diameter of 20-30 nm,niobium pentoxide nanobelts with a width of around 200 nm and niobium pentoxide nanorods with a diameter of around 500 nm.Those niobium pentoxide nanostructures prepared by hydrothermal and solvothermal methods mainly follow the[001]zone direction with the predominant（001）exposed on the bundle surfaces.While the niobium pentoxide nanorods made by molten-salt method mainly follow the the[001]zone direction,even they also adopt pseudo-hexagonal phase.Then we explored the photocatalytic property of those three one dimensional nanostructures.As expected,the niobium pentoxide nanowires with low diameter exhibits superior photocatalytic property.And photoluminescence spectra show that low-diameter one dimensional nanostructure contains better photo-electronic transfer property.In order to prove the superior photocatalytic property of one dimensional niobium pentoxide nanostructure,we also synthesized niobium pentoxide hollow microsphere using PS as template,and tested its photocatalytic property.Zero dimentioanl niobium pentoxide hollow spheres exhibited superior photocatalytic property than any other one dimensional niobium nanostructures.This thesis also explored the preparation of niobium pentoxide/silver phosphate and niobium pentoxide/carbon nitride composite photo-catalysts using niobium pentoxide nanowires synthesized by solvothermal method as raw material.Especially,we prepared niobium pentoxide/silver phosphate composite photo-catalyst with different molar ratio by adjusting the addition of silver phosphate.Both of the two composite photocatalysts exhibit better photo-electronic property.We find that the enhanced photocatalytic property results from not only its unique band gap,but also its unique heterojunction.One dimensional niobium pentoxide nanostructure promotes the separation of electron-hole pairs and transfer of photo-electronics,which results in better photo-electronic property.Additionally,this thesis also explored the preparation of niobium carbide nanowires using bamboo as template.We mainly explored the influence of the ratio of raw materials and reaction condition on the morphology and constituents of the products.As a result,we prepared well-dispersed niobium carbide nanowires with a diameter of around 100 nm.Niobium carbide nanowires have great potential application in electronic device due to its good electronic property.