Photocatalytic and magnetic behaviors of BiFeO3 thin films deposited on different substrates

Single phase polycrystalline BiFeO3 thin films were grown on three different substrates via chemical solution deposition. Our results indicate that the band gap of as-prepared BiFeO3 films can be tuned (2.02–2.67 eV) by the grain size effects caused by the substrates. These BiFeO3 films show good photocatalytic properties by the degradation of Congo red solution under visible-light irradiation (λ > 400 nm). Additionally, weak ferromagnetic behaviors can be observed at room temperature in all the films, which should be correlated to the destruction of the incommensurate cycloid spin structure of BiFeO3 phase and the coexistence of Fe3+ and Fe2+ as confirmed by X-ray photoelectron spectroscopy.