Ti doped hematite thin film photoanode with enhanced photoelectrochemical properties

Ti-doped Fe2O3 thin films were prepared on fluorine-doped SnO2 substrate as visible light active photoelectrochemical anodes. The fabricated films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD data showed all films exhibited rhombohedral hematite phase, and the cell parameters showed that Titanium atoms substituted Fe atoms in the hematite lattice. AFM demonstrated that Ti doping could decrease the particle size on the surface compared with pure hematite. XPS results presented that Ti atom concentration was about 2.23 % in the doped film surface. The incident photon to electron conversion efficiency of Ti doped alpha-Fe2O3 film reached 23 % at 400 nm under 0.30 V bias versus AgCl in 1 M NaOH, which was nearly four times than that of undoped film. Titanium atoms in alpha-Fe2O3 lattice could increase the conductivity of hematite film. And excited electrons and holes in the bulk film could be separated more efficiently, rather than recombining with each other rapidly as that in pure hematite, which ultimately prolonged the life of electrons and holes and obtained the high efficiency Fe2O3 photo anode.