Synthesis And Photoelectrochemical Performance Investigation Of Low-dimensional Bismuth Vanadate Nanocomposites

With the advantages of environmental protection,photocatalysis has attracted more and more attention in environmental pollution control.It can be used in various applications,such as sterilization,self-cleaning,air purification,fog prevention,heat transfer,heat dissipation and water purification.Traditional photocatalyst TiO₂ has many advantages,such as low cost,high efficiency,good stability,etc.However,it can not absorb visible light and has the disadvantages of high electron-hole pairs recombination efficiency.In order to overcome these shortcomings,great attention has been paid to new photocatalysis,especially visible light-driven semiconductors which have high utilization efficiency in degrading pollutants and converting light energy.Of special interest is the visible light active Bi-based photocatalysts.Bismuth Vanadate stands out from the Bi-based photocatalysts because of its high photocatalytic activity and chemical stability under UV-vis light irradiation,which has great research significance and value.In addition,the coupling between semiconductors can play a synergistic effect,improve the utilization rate of solar energy and reduce the recombination efficiency of electron-hole pairs.Therefore,the construction of heterostructures and the control of morphology have great value for improving the photocatalytic efficiency of photocatalysts.In this paper,we prepared low-dimensional nano-sized Bismuth Vanadate with different morphological structures by hydrothermal method and electrospinning,and the performance control is carried out through the construction of the heterostructure and the doping mode.Finally,the properties of the as-prepared samples are discussed by their photocatalytic degradation of dyes,toxic substances and antibiotics.The main research contents as follows:1. The P-doped BiVO₄ nanofibers was successfully synthesized by electrospinning combined with calcination process.The P-doped BiVO₄ nanofibers have one-dimensional morphology and excellent photocatalytic degradation of tetracycline.Through the study on the UV-vis diffuse reflection of the sample,the absorption capacity of P-doepd BiVO₄ is enhanced and the absorption range has red shift compared with other samples.The as-prepared samples have enhanced photogenerated carrier efficiency and small internal resistance.Further sutduy of the properties of the sample were tested by Mott-Schottky plot.2.0D/1D heterojunction of BiVO₄ quantum dots/ZrO₂ nanobelts have been designed reasonably and successfully synthesized by electrospinning combined with hydrothermal process.The as-prepared sample is composed of Bismuth Vanadate quantum dots and Zirconia nanobelts.Through the Bismuth Vanadate quantum dots with narrow band gap and quantum effect combined with the wide band gap Zirconia nanobelts,the as-prepared samples have strong photocatalytic activity and chemical stability.And the small size gives it a large specific surface area,which enhances the absorption of sunlight.The construction of heterostructures greatly reduced the recombination of electron-hole pairs.The band gap and density of states of Bismuth Vanadate and Zirconia are simulated by DFT method,which further verifies the rationality of experiments.The prepared samples exhibited excellent performance in photocatalytic degradation of Nitrobenzene and Rhodamine B.3. BiVO₄/TiO₂ hierarchical nanofibers have been successfully synthesized by electrospinning combined with hydrothermal process.The experimental results demonstrate that BiVO₄/bi-phase TiO₂ hierarchical nanofibers present a good one-demensional morphology which constitute by BiVO₄ nanorods inlaid into TiO₂nanofibers.This one-dimensional hierarchical heterojunction nanofibers are beneficial to the absorption of solar energy and improve photogenerated carrier transfer efficiency.Moreover,it has lower recombination and higher separation rate of electron-hole pairs.The photoelectroncatalytic activity of the sample are successfully improved by the special morphology and the construction of the heterostructure.4. BiVO₄/Fe₂O₃/ZnFe₂O₄ nanofiber photocatalyst was successfully prepared by reasonable design and electrospinning combined with calcination process.The photogenerated electrons transfer efficiency is improved and the recombination rate of the electron-hole pairs is significantly reduced by the successful combination of three substance.