Photocatalytic oxidation activities of TiO2 nanorod arrays: A surface spectroscopic analysis

Abstract

The correlation between the defect structures of hydrothermally grown TiO2 nanorods (TNR) and their photocatalytic activity has been investigated by using various surface spectroscopic analysis techniques including scanning transmission X-ray microscopy (STXM) and high-resolution photoemission spectroscopy (HRPES). Defect states related to Ti3+ and oxygen vacancies in TNR were observed when the growth time was over 90 min (i.e., those over 500 nm in height), and these TNR samples showed photocatalytic oxidation activity with respect to the molecules 2-mercaptoethanol (2-ME) or 2-aminothiophenol (2-ATP), also confirmed by HRPES. The presence of defect structures on the TNR influences on the electronic states of titanium and oxygen, and thus can improve the catalytic oxidation reactions.