Preparation Of Bismuth Vanadate Film And Study On Its Photoelectrochemical Performance

With the development of society,energy and the environment have become two major problems in the face of human life.Due to the depletion of fossil energy and the deepening of environmental pollution,people are striving to clean,sustainable new energy sources.As a recognized clean energy,hydrogen energy is increasingly favored by researchers.In 1972,since Honda and Fujishima first used TiO₂ semiconductors as photoanode electrode materials to prepare hydrogen,the use of semiconductor photocatalytic decomposition of hydrogen production technology has become one of the most attractive methods,which has received extensive attention from researchers.The selection of semiconductors with chemical stability,non-toxicity and low cost,and the development of photocatalysts with wider photoresponse range and higher photocatalytic efficiency have become the main directions of photocatalysis research.Among most metal oxide semiconductors,the monoclinic phase of BiVO₄ has good photoelectrochemical stability,non-toxicity,narrow band gap and strong absorption in the visible range,and has caused much attention in recent years.Monoclinic BiVO₄ still has some problems to overcome.monoclinic phase BiVO₄ has the disadvantages of lower electron mobility,slower oxidation reaction rate,and photogenerated electron-hole pair recombination,which greatly limits its decomposition efficiency to water.In order to improve these problems,a series of BiVO₄ film samples were prepared by pulsed laser deposition?PLD?technique.The regulation of the morphology,structure and properties of BiVO₄ film was achieved by adjusting the experimental conditions.BiVO₄ films with different growth orientations were prepared by using YSZ with different crystal orientations as substrates.The flexible structure of BiVO4 film is prepared by using Mica substrate,which provides a new choice for flexible photocatalytic devices.This paper mainly carried out the following aspects:?1?BiVO₄ film samples were prepared on YSZ single crystal substrates by pulsed laser deposition.The structure,morphology and photoelectrochemical properties of BiVO₄ films were controlled by adjusting the deposition temperature,oxygen pressure,thickness and laser frequency of the films.The experimental results show that the deposition temperature,oxygen pressure and laser frequency have a great influence on the morphology of the film.When the deposition temperature is 450?C,the oxygen pressure is 10 Pa,the laser frequency is 10 Hz,and the BiVO₄ film thickness is 90 nm,the prepared BiVO₄ film has the best photocatalytic performance and the highest photocurrent density.It is to achieve effective separation of photogenerated electron-hole pairs by adjusting the growth conditions of the film.?2?The growth orientation of BiVO₄ thin films was controlled by using single crystal YSZ[100]?[110]?[111]crystal orientation substrates.The difference in structure and photoelectrochemical properties of BiVO₄ thin films under different growth orientation conditions was systematically studied.The experimental results show that the pure BiVO4 film has a higher photocatalytic effect,while the BiVO₄ film grown along the[001]orientation exhibits more excellent photoelectrochemical properties.This is mainly related to the excellent charge transport performance of[001]oriented BiVO₄ film.?3?A flexible structure of BiVO₄ film was prepared by using Mica as substrate.Taking full advantage of Mica's flexibility,optical transparency and light weight,it has constructed a photocatalytic device with flexible structure.The experimental results show that the flexible structure BiVO4 film has good crystal quality and exhibits strong absorption in the visible range.The relationship between different curvature radius and photoelectrochemical performance of flexible structure BiVO4 film was studied.The results show that it has good photocatalytic performance while maintaining bending.In addition,the photocurrent density of BiVO4 film decreases with the increase of the radius of curvature,which is mainly due to the fact that the film will rupture with the increase of the radius of curvature,increasing the center of electron-hole recombination.