Synthesis And Performance Research Of Low-dimension Vanadate Nanomaterials

In recent years,the environmental pollution has been arose inevitably with the increase of human activities,in which water pollution has been solved urgently.Semiconductor-based photocatalysis has been a potential strategy to solve the problems concerning energy crisis and environmental contamination since TiO₂ was found to efficiently split pure water into H₂ by Fujishima and Honda.However,traditional photocatalysis has fast recombination efficiency of electrons and holes and it can only absorb ultraviolet light that occupying less than 5%of solar energy because of its intrinsic large band gap.These weaknesses of traditional photocatalysis strongly impair its photocatalytic performance and restrict its practical application.The nanomaterials of vanadates due to narrow band gap and efficient visible-light response range have attracted extensive attention for environmental remediation.In this work,low-dimensional heterostructures of vanadates have been rationally designed and fabricated via a combined electrospinning-calcination process.Besides,the energy band structures and density of states of Semiconductor-based heterostructures have been researched combined with first-principle.In addition,the photocatalytic activity and photoelectric performance of the prepared semiconductor heterostructures have been studied in detail.The main research contents are as follows:1.InVO₄/TiO₂ heterostructured photocatalysts were prepared by a simple electrospinning technique.As-prepared samples present one-dimensional porous nanobelts morphologies.The porous structure is advantageous to increase specific surface area and facilitate the transport of reactants and products.Meanwhile,the heterojunction can promote the separation of photogenerated electron-hole pairs.The results demonstrated that InVO₄/TiO₂ heterostructured nanobelts exhibit the higher photocatalytic activity and sustainable circulation efficiency due to its special one-dimensional structure.2.One-dimensional?1D?porous CeVO₄ nanobelts have been prepared by rational design and electrospinning process,as an excellent photocatalyst for visible light degradation of Methylene blue?MB?solution.The band structure and density of states of 1D CeVO₄ nanobelts are simulated by DFT method,and 1D porous CeVO₄ nanobelts possess the stable crystal structure,which contributes to enhanced photocatalytic stability.Accordingly,the 1D nanostructures are beneficial to ultrafast carrier separation,and could reduce diffusion length for charge carriers,promote separation and migration and provide rich catalytically active sites for photoeletrochemical reactions.Benefiting from these structural and compositional features,CeVO₄ nanobelts exhibit the excellent photocatalytic performance and recycling ability,compared with individual CeVO₄ powders upon simulated sunlight irradiation.3.With TiO₂ nanofibers as a starting point,one-dimensional CeVO₄/TiO₂heterostructures,via electrospinning and post solvothermal route,have been controllably synthesized.We demonstrated that the slantwise growth of CeVO₄nanorods on the surface of TiO₂ nanofibers was in favor of efficient separation of photogenerated charges.Furthermore,the microstructures of hierarchical CeVO₄/TiO₂heterostructures were characterized in detail and their photoelectrocatalytic properties were comprehensively investigated.Compared with pure individual CeVO₄ and TiO₂nanomaterials,it was found that one-dimensional hierarchical CeVO₄/TiO₂heterostructures possessed the extraordinary photoelectric properties under simulated sunlight irradiation,owing to their distinctive hierarchical structures and synergistic enhancement effect between CeVO₄ and TiO₂ that may not be attainable otherwise.4.One-dimensional superfine Ni₃?VO₄?₂ nanofibers with diameter about 60±5 nm have been successfully synthesized by simple and efficient electrospinning process.The construction and photoelectrochemistry performance of photocatalysts are characterized in detail.Moreover,the energy band structure,density of states and free energy of different crystal planes of Ni₃?VO₄?₂ have been simulated by density functional theory?DFT?and explained in detail.The relationships between the structures and photoelectrochemistry activities are also discussed detailedly.Compared with Ni₃?VO₄?₂ powders,superfine Ni₃?VO₄?₂ nanofibers possess the excellent photoelectric properties,which could be attributed to minor diameter of nanofibers providing the large surface area.