Photoelectrochemical performances of the SnO2-TiO2 bilayer composite films prepared by a facile liquid phase deposition method

A facile liquid phase deposition (LPD) method was developed to prepare the SnO2-TiO2 bilayer composite films in this paper. The phase structure, surface morphology, and chemical composition of the as-prepared films were analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. It was observed that, the underlying TiO2 film consisted of nanorods and showed an acicular surface morphology, whereas the outer SnO2 layer consisted of tiny SnO2 nanosheets and exhibited a network-like surface morphology. The XPS results confirmed that the as-prepared LPD-derived SnO2-TiO2 composite films were co-doped with nitrogen and fluorine. Moreover, the photoelectrochemical measurements indicated that a typical n-type photoeffect were observed for the as-prepared LPD-derived films when illuminated by light. It was also found that, the photoelectrochemical performances of the SnO2-TiO2 bilayer composite films prepared with 0.1 M and 0.002 M (NH4)2TiF6 solutions could be relatively enhanced than that of the TiO2 monolayer films.