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 12h 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 1.0μm 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 1.0–2.0μm in size. Optical studies showed that the Bi2Ti2O7 film had a direct band gap of 2.74eV. The photoelectrochemical properties of Bi2Ti2O7 were tested and it was found that the electrodes exhibited a photocurrent density of 1.8μAcm−2 at 0.23V vs. Ag|AgCl. Results showed that Bi2Ti2O7 is an attractive material for photoelectrochemical water splitting. •The phase pure Bi2Ti2O7 pyrochlore was fabricated by AACVD for the first time.•The produced thin films were highly nanostructured.•It was found that Bi2Ti2O7 had a band gap of 2.74eV.•Valence and conduction band energies were 0.64V and 3.38V, respectively, vs. NHE.•It was found that this material is suitable for photolectrochemical water splitting.