Ag-Pi/BiVO₄ heterojunction with efficient interface carrier transport for photoelectrochemical water splitting

The limitation of pristine BiVO₄ photoanode severely causes the high carrier recombination efficiency and low energy conversion efficiency in the photoelectrochemical (PEC) system. In this work, the Ag-Pi/BiVO₄n-n heterojunction has been rationally designed and fabricated for efficient PEC water splitting, through successive ionic layer adsorption reaction method. The built-in field of Ag-Pi/BiVO₄ significantly promotes the separation efficiency of photogenerated carriers, benefiting for the participation of abundant holes in water oxidation. The photocurrent density of 40-Ag-Pi/BiVO₄ has been enhanced to 2.32 mA/cm², which is 4.5 times than that of the pristine BiVO₄. Compared with the pristine BiVO₄ (6.5%), the IPCE value of 40-Ag-Pi/BiVO₄ achieves 22% (410 nm, 1.23V_RHE). In addition, the charge injection efficiency (η_injection) and charge separation efficiency (η_separation) of 40-Ag-Pi/BiVO₄ have been achieved to 74.36% (1.23 V_RHE) and 31.57% (1.23 V_RHE), respectively, revealing the excellent carriers' transfer behavior in the both bulk and interface. The desirable stability endows Ag-Pi/BiVO₄ system with a great potential in the practical application in PEC water splitting, and the corresponding mechanism for in-depth understanding the process of carriers' transfer in Ag-Pi/BiVO₄ structure has been also proposed. Therefore, the construction of Ag-Pi/BiVO₄ heterojunction will provide a new insight for the configuration of efficient PEC system.