Heterostructure Fe2O3/BiVO4 as a Photoanode for a Visible-Light-Responsive Photocatalytic Fuel Cell

Searching earth-abundant materials for photocatalytic fuel cells (PFCs) remains an important goal for energy conversion and storage, and the construction of semiconductor composite materials is an effective method to improve the photochemical properties of photoelectrodes in PFCs. Herein, a simple hydrothermal method is used to load an Fe2O3 layer on a BiVO4 film for use in the photoanode of a PFC, and the electrochemical results show that the short-circuit current density (Jsc) and the open-circuit voltage (Voc) of the PFC reach 3.05 mA/cm2 and 0.84 V under simulated solar irradiation, respectively. Furthermore, a detailed analysis of the density of states, charge density difference, and work functions of the Fe2O3/BiVO4 heterojunction is discussed by the density functional theory (DFT) method, showing the proper band alignment and the existence of a built-in electric field at the interface with the direction from BiVO4 to Fe2O3, which greatly improves the performance of the PFC. This research provides a clear mechanism for the Fe2O3/BiVO4 heterojunction in the PFC system.