A coupled WO3/BiVO4 thin film has been deposited on FTO substrate by a spin coating method from precursor solutions. The composite films were characterized by AFM, SEM, XPS and XRD techniques. The incident photon to current efficiency (IPCE) of BiVO4 electrode was increased by ten times when a WO3 film was layered between the BiVO4 layer and the FTO substrate. The enhanced performance of WO3/BiVO4 composite film electrode is mainly ascribed to the effective electron-hole separations at the semiconductor heterojunction. A schematic mechanism of charge transfer was proposed to explain the photocurrent enhancement for the WO3/BiVO4 electrode surface
