SPR enhanced photocatalytic properties of Au-dispersed amorphous BaTiO3 nanocomposite thin films

All the samples except for the pristine BaTiO3 film exhibit a typical absorption peak in the wavelength region of 580-620 nm due to the SPR effect of Au nanoparticles (NPs). Since the Fermi level of BaTiO3 (Ef(BaTiO3), −5.3 eV) is more negative than that of Au (Ef(Au), −5.1 eV), both of which would adjust their Fermi energy levels to reach a new equilibrium Fermi level Ef(Au/BaTiO3). When the photocatalyst is irradiated by photons with energy no less than the energy gap of BaTiO3, the electrons (e−) in the valence band (VB) could be stimulated to the conduction band (CB). As the bottom level of CB of BaTiO3 is higher than Ef(Au/BaTiO3), the photoexcited e− would transfer from the CB of BaTiO3 to Au actuated by the above potential energy, which can effectively promote the separation of e− and h+, finally enhancing photoactivity.160