Photoelectrocatalytic oxidation of phenol for water treatment using a BiVO₄ thin-film photoanode

The removal of organics by photoelectrocatalytic oxidation offers a viable option to remove the contaminants at low concentrations. In this paper, we propose a BiVO4 thin films synthesized via spray pyrolysis for photoelectrocatalyic oxidation of phenol with solar light. We compare the properties of BiVO4 with those of the commonly used photocatalyst TiO2. In addition, BiVO4 films with W gradient doping were fabricated and tested for improving the photocatalytic performance of BiVO4. X-ray diffraction, atomic force microscopy, incident photon to current efficiency and spectrophotometry have been conducted for BiVO4 films of different thicknesses, as well as for TiO2. The electrochemical impedance spectroscopy and dark conductivity measurements were conducted. Phenol removal has been measured for both the TiO2 and BiVO4 samples. The best performance was found to be for a 300 nm undoped BiVO4 film, being able to reduce the phenol concentration up to 30.0% of the initial concentration in four hours.