Fabrication and photoelectrochemical studies of Bi2Ti2O7 pyrochlore thin films by aerosol assisted chemical vapour deposition

Phase pure thin film Bi2Ti2O7 photoelectrodes were produced by aerosol assisted chemical vapour deposition at 600 °C for the first time. X-ray diffraction analysis showed that the as-deposited Bi2Ti2O7 films were amorphous in nature; however, post-deposition annealing at 600 °C for 12 h significantly increased the crystallinity to give phase pure Bi2Ti2O7. Scanning electron microscopy revealed that the as-deposited film had a cauliflower-like structure with features ranging from 0.5 to 1.0 μm in size. It was found that the post-annealing step sintered the features together reducing the pores in the structure and giving rise to larger features of 1.0-2.0 μm in size. Optical studies showed that the Bi2Ti2O7 film had a direct band gap of 2.74 eV. The photoelectrochemical properties of Bi2Ti2O7 were tested and it was found that the electrodes exhibited a photocurrent density of 1.8 μA cm−2 at 0.23 V vs. Ag|AgCl. Results showed that Bi2Ti2O7 is an attractive material for photoelectrochemical water splitting.