Electrochemical In-situ Synthesis and Photocatalytic Properties of BiF3 Thin Films

BiF3 thin films were prepared by simple in-situ electrochemical method at room temperature. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflection spectroscopy (UV-Vis DRS) and density functional theory (DFT) were employed to characterize the crystallinities, structures, morphologies, optical properties and energy band structures of the as-prepared BiF3 thin films. The photocatalytic activity and stability of BiF3 thin films were evaluated by the degradation of Rhodamine B(RhB) under simulated sunlight irradiation. The results show that the BiF3 thin films exhibit the nanosheet structure with high purity, excellent photocatalytic activity and stability. The conduction band minimum and the valence band maximum of BiF3 thin films are mainly contributed by Bi-6p and F-2p orbital electrons, respectively. It was also found that, with the increase of electrolyte concentration, the structural morphologies of BiF3 thin films changed, resulting in that the photocatalytic activity of BiF3 thin films first enhances and then decreases. When the electrolyte concentration is 1.5%, the BiF3 nano-film is obviously staggered, which is conducive to the transport of reactants and light reflection, thereby increasing the reaction space of catalyst and the utilization efficiency of light. The photocatalytic degradation efficiency of RhB reaches 99.2% after 5 h simulated solar light irradiation, and still remains above 81% after being used 4 times. The possible formation mechanism of BiF3 thin films on Bi plate via novel in-situ electrochemical method was proposed.