Preparation And Photoelectric Properties Of CuBi₂O₄-based Photocathode

Photochemical water splitting to produce hydrogen is a promising method to solve the problem of fossil fuel shortages due to the carbon-free and high-energy characteristics of hydrogen.In fact,the direct reduction of water to hydrogen using semiconductors has been widely studied because it uses only widely distributed water and sunlight.Therefore,CuBi₂O₄?CBO?has attracted attention as a p-type semiconductor photocathode material with rich content,potential and narrow band gap?1.5-1.8eV?.However,its photoelectric separation is limited due to its low carrier separation efficiency and poor stability.In order to solve these problems,we focused on the effects of heterojunction,protective layer,homojunction and surface treatment on the photocatalytic activity of CBO.The main content is divided into two parts:1.We designed to use ZnSe and P25 to modify the CBO film,thereby obtaining a stable and efficient CuBi₂O₄/ZnSe/P25 photocathode.The results show that this new type of photocathode has an outstanding current density of 0.43 mA/cm²,which is more than twice that of pure CBO.Systematic studies show that the good performance of photoelectrodes is attributed to the heterostructure between ZnSe and P25,the high electron mobility of ZnSe and the hole extraction ability of CBO.In addition,the P25protective layer can effectively prevent the photoelectrode from contacting with the electrolyte and improve the stability?testing for 5000 s,nearly 90%of the photocurrent is retained?.Therefore,our results can provide effective strategies for designing high-performance CBO-based photocathode materials.2.We propose a regrowth strategy for preparing CBO coatings on Zinc-doped CBO.Further,the treatment of CBO/Zn-CBO with NaBH₄ introduced oxygen vacancies?O_v?on CBO/Zn-CBO.The study found that the doping of zinc not only increased the carrier concentration of CBO,but also changed the energy band of CBO appropriately to form a homojunction.This homojunction can effectively promote the separation of electron-hole pairs,resulting in excellent photocurrent density?0.5 mA/cm² at 0.3 V vs.RHE?and charge separation efficiency?1.5 times higher than CBO?.Subsequent surface treatment introduced O_v on CBO/Zn-CBO,which significantly increased the active area of the surface catalytic reaction and further increased the photocurrent density?0.6mA/cm²?.In the absence of a promoter,the electron injection efficiency of O_v/CBO/Zn-CBO is 1.47 times that of CBO.In this work,a homojunction type photocathode with O_v regulation is studied,which provides a new idea for the future photoelectrochemical water splitting.