Preparation of nanoporous BiVO/TiO/Ti film through electrodeposition for photoelectrochemical water splitting.

A nanoporous BiVO/TiO/Ti film was successfully fabricated by electrodepositing a nanoporous BiOI film on nanoporous TiO arrays followed by annealing at 450°C for 2 h. The electrodeposition of BiOI film was carried out at different times (10, 30, 100, 500 and 1000 s) in Bi(NO) and KI solution. The morphological, crystallographic and photoelectrochemical properties of the prepared BiVO/TiO/Ti heterojunction film were examined by using different characterization techniques. UV-vis spectrum absorption studies confirmed an increase in absorption intensities with increasing electrodeposition time, and the band gap of BiVO/TiO/Ti film is lower than that of TiO/Ti. The photocatalytic efficiency of BiVO/TiO/Ti heterojunction film was higher compared to that of the TiO/Ti film owing to the longer transient decay time for BiVO/TiO/Ti film (3.2 s) than that of TiO/Ti film (0.95 s) in our experiment. The BiVO/TiO/Ti heterojunction film prepared by electrodeposition for 1000 s followed by annealing showed a high photocurrent density of 0.3363 mA cm at 0.6 V versus saturated calomel electrode. Furthermore, the lowest charge transfer resistance from electrochemical impedance spectroscopy was recorded for the BiVO/TiO/Ti film (1000 s) under irradiation.