Study On The Preparation And Photoelectric Performance Of TiO₂ Nanotubes Sensitized By Bi-based Semiconductor Nanoparticles

Semiconductor photocatalyst can effectively utilize abundant and environmental protection sunlight energy,and can effectively deal with the problems caused by energy shortage and environmental pollution.However,traditional semiconductor photocatalysts,such as TiO2 and ZnO,have low utilization of sunlight,slow carrier migration,and high photo-generated electron-hole pair recombination rates due to their inherent properties caused by wide band gap.Therefore,the preparation of new photocatalysts that meet the requirements of the times with high solar light utilization rate and low photogenerated electron hole recombination rate has always been a severe test for global researchers.Compared with traditional TiO2 powders,TiO2 nanotube arrays?NTs?have a highly ordered morphology,high specific surface area,and special tubular electron channels,which is beneficial for coupling with narrow-band semiconductor materials to prepare efficient photocatalysts.Bismuth-based semiconductor materials are hot candidates.Most bismuth-based semiconductor materials have high visible light capture capabilities,special layered structures,and can form effective binding with TiO2 to construct high-performance photocatalyst.Therefore,in this paper,TiO2 nanotube arrays were successfully fabricated on Ti mesh/Ti foil substrates and the Bi2O3,BiOBr,BiOI,Bi₂MoO₆,and Bi₂WO₆ are selected as typical representatives to prepare bismuth-based semiconductor nanoparticle-sensitized TiO2 NTs photocatalysts.Briefly as follows:?1?The TiO₂ NTs were successfully prepared on the Ti mesh substrate by anodization.It is found that the diameter and length of nanotubes increase with the increase of oxidation voltage,and the wall thickness is basically unchanged.The photoelectric conversion and photocatalysis tests show that TiO₂ NTs exhibit excellent photoelectric conversion and catalytic performance under the sunlight.The photocurrent density is 1.63 mA/cm²,and the catalytic efficiency for methyl orange?MO?,methylene blue?MB?and rhodamine B?RhB?is 71.31%,98.07%and 51.39%,respectively.?2?The binary heterojunction photocatalysts of Bi2MoO6-TiO2 NTs,BiOI-TiO2NTs/Ti foil and BiOI-TiO₂ NTs/Ti mesh were prepared by solvothermal and successive ionic layer adsorption and reaction?SILAR?methods,respectively.The morphology,phase structure,element composition and optical properties of binary heterojunction photocatalyst were observed by scanning electron microscope?SEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and diffused reflectance spectrum?DRS?,respectively.The methyl orange?MO?,methylene blue?MB?,rhodamine B?RhB?and Cr⁶⁺were used to simulate organic dye wastewater and heavy metal wastewater,respectively.The photocatalytic test showed that the binary heterojunction photocatalyst showed excellent removal performance,and the corresponding removal efficiency was 100%,100%,97.28%and 98.12%,respectively.The high performance of PEC is attributed to effective visible light absorption and heterojunction structures that promote efficient photoelectron separation.?3?The tenaey heterojunction photocatalysts of Bi/Bi2O3-TiO2 NTs,Bi2WO6/WO3-TiO2 NTs,BiOBr/AgBr-TiO2 NTs was respectively prepared by adjusting the concentration of cetyl trimethyl ammonium bromide?CTAB?and glucose(C₆H₁₂O₆).The morphology,phase structure,element composition and optical properties of the binary heterojunction photocatalyst were observed by SEM,XRD,XPS and DRS,respectively.The result show that the Bi/Bi2O3,Bi2WO6/WO3,BiOBr/AgBr can be tightly combined with TiO2,which can significantly improve the visible light response.The photoelectric conversion performance of the ternary heterojunction photocatalyst was tested by an electrochemical workstation.As a result,the photocurrent of the surface-sensitized TiO2 NTs was significantly enhanced,the interface resistance was reduced,and the carrier migration was accelerated.The removal experiments show that the ternary heterojunction photocatalyst can effectively remove the organic dye and heavy metal Cr⁶⁺in water.The three components complement each other and rely on each other to show effective synergy,which lays the foundation for the development of new multi-component photocatalysts and is conducive to effectively solving the problem of energy shortage and environmental pollution.