Enhanced photoelectrochemical performance of WO3/Ti photoanode due to in situ formation of a thin interfacial composite layer

► Nanocrystalline monoclinic WO3 films are grown on treated Ti substrates using doctor-blade method. ► Photoelectrochemical response of WO3 on polished Ti is enhanced relative to that on unpolished Ti substrate. ► Photocurrent enhancement is attributed to in situ formation of an interfacial WOx-TiOy layer between WO3 and polished Ti. ► WOx-TiOy layer promotes the charge separation and improves the interfacial charge-transfer processes.