Rationally Designed Heterojunction on a CuBi2O4 Photocathode for Improved Activity and Stability during Photoelectrochemical Water Reduction

Abstract CuBi 2 O 4 (CBO) is a promising photocathode for photoelectrochemical (PEC) water reduction, whereas the disadvantages of poor stability and severe charge recombination still hinder its application. In response, we designed a stabilized, efficient CBO/ZnSe/P25 (CBO/ZS/P25) photocathode with the CBO film modified by ZS and P25. As a result, this novel photocathode exhibited an outstanding current density of 0.43 mA/cm 2 , more than twice that of CBO. Systematic studies reveal that the high performance is attributed to heterojunction formation between ZS and P25, high electron mobility of ZS and hole extraction capacity of CBO. Besides, P25 protective layer can effectively blocks contact with the electrolyte and enhance the stability (retained nearly 90 % of the photocurrent after testing 5000s). Therefore, our results can provide an efficient strategy to design high performance CBO‐based photocathode material.