Tuning optical band gap by electrochemical reduction in TiO2 nanorods for improving photocatalytic activities

Abstract

In this study, we investigate the tuning of the optical band gap of TiO₂ nanorods (TiO₂ NRs) by electrochemical methods for improving their photocatalytic activities. A seed layer prepared by RF-magnetron sputtering is employed to increase the adhesion between TiO₂ NRs and substrate to prevent the peel-off of TiO₂ NRs from substrate during electrochemical reduction process. The morphological study shows the stability of TiO₂ NRs structure after reduction process. The electrochemical reduction process increased the amount of Ti³⁺ (a reduced state of Ti⁴⁺) and oxygen vacancy by 2.2% and 3.6%, respectively. The process also tune the optical band of TiO₂ NRs from 3.0 eV to 2.84 eV due to the up-shift of valence band to Fermi level. The reduced band gap of NRs improve the photocatalytic activities by 1.48 times due the increase of its absorbance range from UV to visible in solar spectrum. The photocatalytic activities were 24.3 times improved by depositing a ultrathin layer of Pt as electron collector.