Ethanol vapor processing of titania nanotube array films: enhanced crystallization and photoelectrochemical performance

Abstract

A significant enhancement in the photoconversion efficiency of anodically grown, thermally annealed titania nanotube array photoanodes was observed when subjected to an ethanol vapor treatment that resulted in improved crystallization. Ethanol vapor treatment of 6 µm long vertically aligned titania nanotube array films initially annealed at 580 °C for 6 h in an oxygen environment, under autogeneous pressure at 140 °C (≈50 psi), resulted in an increase of up to ∼30% in the photoconversion efficiency. A significant improvement in the crystallinity as revealed by glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy studies as well as incident photon to current conversion efficiency (IPCE) is observed in the vapor treated samples.