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

Abstract

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, 1.23VRHE). In addition, the charge injection efficiency (ηinjection) and charge separation efficiency (ηseparation) of 40-Ag-Pi/BiVO4 have been achieved to 74.36% (1.23 VRHE) and 31.57% (1.23 VRHE), 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.