| Hydrogen production by water splitting has great potential in producing sustainable hydrogen energy and solving the pollution problems caused by the widespread use of fossil fuels.In recent years,it has attracted widespread attention in the scientific research community.Therefore,seeking high-performance and stable photoanode semiconductors is the key to photoelectric catalytic water splitting technology.As an n-type semiconductor,monoclinic scheelite Bi VO4（BVO）has a suitable band gap（2.4 e V）that can absorb visible light and a suitable positive valence band edge for sufficient oxygen reaction.However,due to the original BVO The carrier transmission efficiency is slow,and the electron-hole recombination is serious,which makes it difficult for the photocurrent density to reach its theoretical value(7.5m A/cm-2)in practice.Therefore,in view of the above defects,our work mainly optimizes the internal structure of BVO,the loading of high-efficiency catalysts on the surface and the hydrogen pretreatment,etc.,which greatly improves its water splitting performance.The specific research content is as follows:In the first part of the work,we used the CVD method to dope Mo atoms on the surface of the BVO,thereby inducing the restructuring of the surface crystal orientation,with abundant oxygen vacancies.After Mo atom doping,some nano-BVOs with（121）crystal orientation are formed on the crystal plane of BVO（110）,and there are a lot of oxygen vacancies on the BVO photoanode.Compared with the original BVO,the Mo-doped BVO photoanode（Mo:BVO）showed a significant improvement in photocurrent（～1.63 times）.In addition,we used graphene as the holes extraction layer and Co Pi as the co-catalyst.Finally,the Co Pi/Gr/Mo:BVO photoanode showed an impressive photocurrent density of 4.36 m A/cm-2,with the initial potential relative to RHE is 0.3 V.In the second part of the work,a simple hydrothermal method was used to successfully synthesize a transparent Co3Fe1Ox nano-film on the surface of BVO,and the ratio of Co and Fe atoms was adjusted to achieve the best photoelectric catalytic performance.The starting potential is 0.3 V relative to RHE,the photocurrent is4.0m A/cm-2,and 1.23 V vs.RHE under AM 1.5 G illuminations.In addition,it showed good stability,and the activity did not decrease significantly after 10 hours of reaction.In the third part of our work,we synthesized the BVO crystal film by electroplating,and then pretreated with hydrogen to induce a large number of oxygen vacancies in the BVO.In addition,the morphology characterization,XPS analysis and photoelectrochemical performance test proved the increase of oxygen vacancies and the improvement of photoelectric performance. |
