Modification And Photochemical Properties Of Bismuth Vanadate Photoanodes

Converting solar energy into hydrogen by photoelectrochemical（PEC）water splitting is one of the promising ways to solve the energy and environmental problems caused by fossil energy.Efficient photoanodes are key components of PEC energy conversion and storage systems.Bismuth vanadate（BiVO₄）has emerged as a promising metal oxide photoanode,due to its suitable band position and band gap width.However,BiVO₄ suffers from serious recombination of photogenerated charges and sluggish oxygen evolution reaction（OER）kinetics,which limits its application in PEC water splitting.In this study,the PEC performance of photoanode was improved by c onstruction of heterojunction and loading oxygen evolution cocatalyst.The main contents are carried out as follows:1.Study on PEC performance of metal Bi modified BiVO₄（BiVO₄|Bi）photoanode:Aiming at the problems of low photogenerated charge separation efficiency and short service life of BiVO₄ photoanode,BiVO₄ photoanode modified with metal bi was prepared by in-situ reduction on the surface of BiVO₄ photoanode.Through the construction of BiVO₄|Bi heterojunction,the interface electric field which is conducive to the migration of photogenerated holes from BiVO₄ to metal Bi is formed,and the separation efficiency of photogenerated charges is improved.The highest photogenerated charge separation efficiency of BiVO₄|Bi photoanode can be increased to 2.5 times of BiVO₄ photoanode.The photocurrent density of BiVO₄|Bi composite photoanode is 1.23 V vs.RHE is 2.45 m A/cm²,which is 2.63 times of BiVO₄photoanode.Meanwhile,the initial potential of BiVO₄|Bi composite photoanode moves to negative direction by 60 m V relative to BiVO₄ photoanode.2.Study on PEC performance of CoOOH modified BiVO₄|Bi（BiVO₄|Bi|CoOOH）photoanode:Aiming at the problem of slow water oxidation kinetics on the surface of BiVO₄|Bi photocatalyst,CoOOH was loaded on the surface of BiVO₄|Bi photocatalyst.The excellent electrocatalytic performance of CoOOH improves the charge transfer behavior at the interface between the photoanode and electrolyte.The injection efficiency of photogenerated holes in BiVO₄|Bi|CoOOH photoanode is as high as 65%.Compared with BiVO₄ photoanode,the initial potential shifts to a negative direction by 450 mv,and reaches 2.45 m A/cm² at 1.23 V vs.RHE,which is 2.58 times of BiVO₄photoanode.