Mechanism for enhancement of visible light response on nitrogen-doped TiO2 by modification with vanadium species.
Photocatalytic activities of nitrogen-doped TiO2 (N-TiO2) will remarkably increase by surface modification with vanadium (+V) species for the decomposition of volatile organic compounds (VOCs) in the presence of O2 under visible light irradiation. Study on the electron spin resonance (ESR) shows that the vanadium (+V) species interacted with N-TiO2 surface is photo-reduced to form vanadium (+IV) in vacuum or in the presence of hole scavengers under visible light irradiation, and subsequently, it is re-oxidized into vanadium (+V) by O2. Furthermore, the concentration of visible light induced holes (.N radicals) on V-oxide/N-TiO2 is much higher than that on N-TiO2. Therefore, it is confirmed that the added vanadium species having oxidation states between +IV and +V that interact with surface N-TiO2 play significant roles as redox mediators in the effective charge separation of holes and electrons, which consequently brings about an enhancement of photocatalytic activity.
Higashimoto
Shinya
S
Department of Applied Chemistry College of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka 535-8585, Japan.
Ushiroda
Yoshiaki
Y
Azuma
Masashi
M