Production of hydrogen by water splitting in a photoelectrochemical cell using a BiVO4/TiO2 layered photoanode

BiVO4/TiO2 layered photoanode was prepared by simple methods, such as sol-gel and metal organic decomposition processes. The photoanode was studied for hydrogen production by water splitting under simulated solar irradiation. Various multilayer configurations of the film were electrochemically tested. The optimal combined photocatalyst consisted of four bottom BiVO4 layers covered by four TiO2 layers on the top. This optimal layered film was characterized by XRD measurements, which showed the presence of the most photoactive phases of BiVO4 and TiO2. The energy band gap measured by diffuse reflectance spectroscopy demonstrated a small blue shift compared to pure BiVO4. Solar-to-hydrogen efficiency reached 1.1% at 1.08V vs. RHE. The corresponding faradaic efficiency was 64%. The photocurrent at 2.08V vs. RHE for the optimal BiVO4/TiO2 photoanode was approximately 5.5mA/cm2. Hydrogen production rate was measured at different external bias from 1.08 to 2.08V vs. RHE and the cumulative production reached 0.6mmol after 10hours of irradiation at 2.08V, which was the highest reported for the BiVO4/TiO2 system.