Surface Morphology and Growth of Anodic Titania Nanotubes Films: Photoelectrochemical Water Splitting Studies

Abstract

Design and development of one-dimensional nanoarchitecture titania (TiO) assemblies have gained significant scientific interest, which have become the most studied material as they exhibit promising functional properties. In the present study, anodic TiO 2 films with different surface morphologies can be synthesized in an organic electrolyte of ethylene glycol (EG) by controlling an optimum content of ammonium fluoride (NH 4 F) using electrochemical anodization technique. Based on the results obtained, well-aligned and bundle-free TiO 2 nanotube arrays with diameter of 100 nm and length of 8 μm were successfully synthesized in EG electrolyte containing ≈5 wt% of NH 4 F for 1 h at 60 V. However, formation of nanoporous structure and compact oxide layer would be favored if the content of NH 4 F was less than 5 wt%. In the photoelectrochemical (PEC) water splitting studies, well-aligned TiO 2 nanotubular structure exhibited higher photocurrent density of ≈1 mA/cm 2 with photoconversion efficiency of ≈2% as compared to the nanoporous and compact oxide layer due to the higher active surface area for the photon absorption to generate more photo-induced electrons during photoexcitation stage.