Preparation Of BiVO₄-based Photoelectrode And The Photoelectrochemical Performance

The global energy crisis caused panic among all mankind,and prompted people to find alternative new energy.At present,the development and application of photocatalyst technology provide us a new thinking to solve the problem of environmental pollution and energy scarcity.Among them,photoelectrocatalytic hydrogen production technology is one of the most effective ways to obtain clean energy hydrogen.In the photoelectrochemical water decomposition reaction,the sunlight and the semiconductor is the main component.The performance of the catalyst directly determines the efficiency of the photoelectric water splitting reaction.Therefore,it is an urgent task that the development of new catalysts and modified phtoanode materials to make it effective in the field of photoelectric water decomposition.In this study,a series of new Bi VO4-based photoanode materials were prepared by simple method,such as electrochemical deposition,photoreduction deposition,calcination,hydrothermal and electrophoretic deposition.Structure,morphology and optical properties of the samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and UV-vis diffuse reflectance(DRS).And photochemical properties of the samples were analyzed by linear scanning voltammetry(LSV),time-current curve(I-t),AC impedance spectroscopy(EIS),photoelectric conversion efficiency(IPCE).Finally,photochemical water decomposition experiments were carried out in self-made H-type photochemical reactor,and the hydrogen production performance of photolysis of a series of Bi VO4-based photoanode films was evaluated.The main research contents are as follows:1.The metal-semiconductor Bi/Bi VO4 thin films were synthesized by electrochemical deposition method combined with calcination and photo-assisted reduction deposition.The photoelectronchemical water splitting of samples was tested on a 300 W xenon lamp,0.5 M Na2SO4 electrolyte,plus 0.1 V bias.The results show that the hydrogen production performance of Bi/Bi VO4 composite thin film electrode is higher than that of pure Bi VO4 film.And the photocatalytic activity of Bi/Bi VO4-60 was the best for 60 min.The reaction mechanism of this new type photoanode material is proposed.2.The same Bi VO4 thin film was synthesized by electrochemical deposition and calcinations.A flower-like Cu S powder catalyst was prepared by simple solvothermal method.Cu S/Bi VO4 composite was synthesized by dropping method.Simultaneously,photoelectrochemical performance of samples was tested by photoelectrochemical water decomposition experiment under visible light.The results show that Cu S is not only beneficial to enhance the absorption of visible light by Bi VO4,but also promote the separation of photogenerated carriers,thus effectively improving the photocatalytic activity of Bi VO4.3.The leaf-structure Bi VO4 film was prepared by a modified electrochemical deposition method combined with calcinations,and their composite Ni Fe2O4/Bi VO4 and Co Fe2O4/Bi VO4 were prepared via electrophoretic deposition.The experimental results show that the photoelectric properties of the composites are higher than that of the pure Bi VO4,This is because Ni Fe2O4,Co Fe2O4 nanoparticles not only broaden the absorption range of the bulk catalyst,but also effectively promote the separation of electron-hole pairs,but also play a role in the catalyst to reduce the oxygen over-potential.