Nanocrystalline WO3 film with high photo-electrochemical activity prepared by polymer-assisted direct deposition

Highly photoactive, nanocrystalline WO3 films were fabricated by an economic solution process based on polymer-assisted direct deposition. The optimized film exhibited a photocurrent of 2.3 mA cm−2 (at 1.23 V vs. reversible hydrogen electrode) under simulated solar illumination (air mass 1.5 global) and a maximum incident photon to current efficiency of 71% at an incident wavelength of 340 nm. The observed performance represents one of the highest values reported for WO3. High crystallinity, porosity and optimum thickness of nanocrystalline films were identified as the critical variables that induce the high photoactivity.