Fabrication and photoelectrochemical studies of Bi_2Ti_2O_7 pyrochlore thin films by aerosol assisted chemical vapour deposition

摘要

Phase pure thin film Bi_2Ti_2O_7 photoelectrodes were produced by aerosol assisted chemical vapour deposition at 600 ℃ for the first time. X-ray diffraction analysis showed that the as-deposited Bi_2Ti_2O_7 films were amorphous in nature; however, post-deposition annealing at 600 ℃ for 12 h significantly increased the crystallinity to give phase pure Bi_2Ti_2O_7. 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 Bi_2Ti_2O_7 film had a direct band gap of 2.74 eV. The photoelectrochemical properties of Bi_2Ti_2O_7 were tested and it was found that the electrodes exhibited a photocurrent density of 1.8 μAcm~(-2) at 0.23 V vs. AglAgCl. Results showed that Bi_2Ti_2O_7 is an attractive material for photoelectrochemical water splitting.