Photocatalytic And Photoelectric Performance Of Nano TiO₂ Film Under Visible Light Irradiation

In the twentyfirst century,energy and environment issues have become to the focus of researchers as two major challenges for human society.Solar energy could be fully untilized by semiconductor TiO₂ for degrading environmental pollutants.Most traditional photocatalysts are dispersed in degradation solu tion in form of particles,which are difficult to recycle,causing secondary pollution.And due to wide band gap of TiO₂,only ultraviolet light can be adsorbed which accounts⁴%in solar energy.What's more,the quantum efficiency is quite low for TiO₂.In order to solve these problems,self standing TiO₂ nano structure film on specific substrate were prepared.Light adsorbance range of TiO ₂ were broaden to visible irradiation through various physical and chemical methods.And the characterization of nanostructures,degradation and photoelectric properties were all carried out,for optimizing and improving material performance.TiO₂ nanorod arrays?NRAs?thin films were prepared by electron beam evaporation and thermal oxidation.Au,Pt nanoparticles?NPs?were deposited by successive ionic layer adsorptioin and reactioin?SILAR?method,and codeposition Au/Pt NPs-TiO₂ NRAs composite films were obtained.After combination with noble metallic NPs,surface plasmon resonance?SPR?effect and schottky barrier could excite electrons and capture photogenerated charge carriers,which improve the charge separation efficiency effectively and accelerate the photocatalytic reaction.And the degradation efficiency of Au/Pt NPs-TiO₂ NRAs under UV visible light and visible light is 20 and 12 times higher than pure TiO₂.Based on Au/Pt NPs-TiO₂ NRAs film,nanostructure were coated by ultra thin TiO₂ atomic layer deposition?ALD?layer,achieving the protection o f noble metal nanoparticles.It created a new path for charge carrier transfer and promoted rapid reaction as well.Annealing process in the end improved the degree of crystallization and enhanced metal semiconductor heterojunction.The parameters were optimized by orthogonal test.Here the degradation efficiency of2ALD/Au/Pt NPs-TiO₂ NRAs sample with 300 ^oC annealing temperature increased by 52.7%compared with Au/Pt NPs-TiO₂ NRAs.What's more,TiO₂ nanorod arrays were combined with Ag,Ag₂S NPs and graphene oxide into composite material.Significant improvement was found on the degradation efficiency and the current density reached to 2.13 mA·cm^-2 vs.0V for GO/Ag/Ag₂S NPs-TiO₂ NRAs under visible light irradiation.It has been greatly improved compared with similar reported system.TiO₂ nanorods were also obtained by hydrothermal method.Here?-Cu₂V₂O₇NPs were synthesized through aerosol assisted spray pyrolysis?AASP?method and rGO film was loaded by electrophoretic deposition and thermal oxidation.The photocurrent density of rGO/?-Cu₂V₂O₇ NPs/TiO₂ NRAs composite film under LED white light was 6.6 times higher than pure TiO₂ NRAs.What's more,photocurrent of rGO/?-Cu₂V₂O₇ NPs/TiO₂ NRAs after 3 h still maintained 99.1%.The TiO₂ films with high visible light response have been investigated to provide theoretical and practical support for solar photocatalysis.