Studies On Preparation And Photocatalytic Performance Of BiVO₄-based Composites

With the arrival and development of industrial society,modern machinery will inevitably consume energy.The alternative energy is imminently needed.BiVO4 has been regarded as a promising photocatalyst.There are many strategies to inhibit the recombination efficiency of the photoinduced electron-hole pairs and to significantly enhance photocatalytic activity.In this work,the aim is to solve the problem of light response range and recycling.This paper surrounds the objects of preparation,the light response range and the mechanism of improved photocatalytic performance.The light response and photocatalytic properties of BiVO4 will be enhanced by using modifications and methods such as compounding oxide,loading metal and compositing flexible materials.The contents and conclusions of this paper can be expressed as follows:(1)Two-dimensional/three-dimensional Bi2O3/BiVO4@GO heterojunction was fabricated by self-assembly using one-pot solvothermal method.The optical performance,electrical conductivity and photocatalytic performance of pure BiVO4 and Bi2O3/BiVO4@GO composites were studied by using ultraviolet-visible diffuse reflection,electrochemical workstation and photocatalytic degradation experiments.Bi2O3/BiVO4@GO exhibits an enhanced O2 evolution rate of 1828 μmol h-1 g-1,nearly 3 times than that of pure BiVO4(626 μmol h-g-1).The heterostructure of type-II is constructed in Bi2O3/BiVO4@GO composite and promotes the charge separation and transfer.The heterostructures composed of 2D GO and 3D Bi2O3/BiVO4 is expected to play a significant role in promoting electron transfer and providing massive reactive sites,in which GO has high specific surface and allows short electron transport distance.(2)Based on the above Bi2O3/BiVO4@GO composite,the photocatalytic performance of the modified graphene oxide is significantly improved.However,no response to near-infrared restricts the photodegradation efficiency of BiVO4.Therefore,to solve the problem,we report a new method to in-situ synthesize non-noble metal Bi decorated mulberry-like BiVO4 by a two-step calcination process.The properties of pure BiVO4 and Bi/BiVO4 composite were investigated by ultraviolet-visible diffuse reflection,electrochemical workstation and photocatalytic degradation experiments.The study shows that the as-grown Bi nanoparticles on BiVO4 lead to the red-shift of the absorbance edge,which significantly extends the light absorption from UV into NIR.Bi/BiVO4 shows the highest RhB degradation ability of 80.9%within 120 min irradiation compared to the pure BiVO4(13.6%).In addition,the Bi/BiVO4 shows an enhanced photocatalytic efficiency of 56.2%compared to the pure BiVO4(17.1%)for phenol.The semiconductor-metal heterojunction can reduce the recombination of electrons and holes.Their photocatalytic efficiency is improved by the surface plasmon resonance excitation of the Bi nanoparticles and the synergetic effects between Bi and BiVO4,and the separation of electron-hole pairs in mulberry like BiVO4 is also obviously promoted.(3)Based on the above-mentioned Bi/BiVO4 composite,the powder can be highly dispersed in water,causing secondary pollution and recycling,which greatly limits its practical application.Therefore,in order to solve this problem,the flexible carbon cloth supported non-noble metal Bi decorated BiVO4(CC-BB)was synthesized via the ultrasonic impregnation method.The experiments show that Bi/BiVO4 composites supported on carbon cloth photocatalytic material are flexible and recyclable and have low recombination rate of photogenerated electrons and holes.Carbon cloth acts as a support material with excellent electrical conductivity and builds a flexible photocatalytic material,which can accelerate carrier transport and help increase carrier current separation efficiency.The synergetic effects among Bi,BiVO4 and carbon cloth effectively improve the photocatalytic efficiency and promote the separation of photoinduced electron-hole pairs.CC-BB has the advantages of high catalytic activity and enhanced degradation rate,solving the problem of recycling.