Surface Modification And Photoelectrocatalytic Properties Of BiVO₄ Semiconductor

With the development of economy and science and technology,the demand for energy is increasing.Among them,fossil energy still plays a leading role in the supply of energy and plays a huge role in promoting social development.However,due to the increasing exploitation of fossil energy,the global fossil energy reserves continue to decline.Therefore,researchers urgently need to find alternative renewable energy to alleviate the energy crisis in the future.Among them,solar energy is gradually coming into the researchers’attention due to its advantages of renewable and large amount.Obtaining energy directly from sunlight through photosynthesis is a promising and effective way to solve the energy crisis.A lot of work has been done to find suitable materials and systems to produce chemical fuels using solar energy.One of the most feasible ways is to build a photoelectrochemical cell,which can reduce water to H₂ or CO₂ to carbon based molecules.However,although the semiconductor substrate has some light absorption properties,it still faces many limitations when it is used as the photoanode alone,including the super recombination of photogenerated electrons,low conductivity and poor surface kinetics of water oxidation.In order to improve the defects of semiconductor,two kinds of multi-component photoanode were designed by using BiVO₄ semiconductor as the base material of photoanode.In this paper,two kinds of multi-component photoanode were designed by using BiVO₄ semiconductor as the base material of photoanode.In this paper,the surface of BiVO₄ was modified by hydrothermal deposition method,and Cs⁺modified photoanode cells were prepared.The successful preparation of Cs⁺modified BiVO₄ electrode was confirmed by SEM,mapping and XPS.The photocurrent density of Cs⁺modified photoanode cell is more than 4.60 m A/cm² at 1.23 V vs.RHE,which is about 3 times of that of unmodified BiVO₄ electrode.At the same time,Cs-modified BiVO₄ electrode with cesium borate as electrolyte has excellent photoelectrocatalytic performance in the process of light source and bias deposition.In addition,WO₃/BiVO₄ composite photoanode was prepared firstly,and Co₃O₄/WO₃/BiVO₄ multi-component photoanode was prepared by impregnating Co₃O₄ prepared by the new method onto the surface of WO₃/BiVO₄ electrode.At 1.23V vs.RHE,the photocurrent density of the composite electrode is more than 4.90mA/cm²,which is significantly higher than that of WO₃/BiVO₄ composite photoanode,indicating that the holes around the semiconductor heterojunction are effectively utilized by Co₃O₄.In the process of electrolysis,the stability of the photoanode was improved obviously by electrodeposition of Co₃O₄ film on the outer layer of the electrode.