Generation of Free OHaq Radicals by Black Light Illumination of Degussa (Evonik) P25 TiO2 Aqueous Suspensions

Catalysts

Haidong Liao¹ 

[1] Wallenius Water AB, Franzéngatan 3, SE-112 51 Stockholm, Sweden

关键词: photocatalysis;    TiO₂;    ^•OH_aq radical;    chemiluminescence;   

DOI  :  10.3390/catal3020418

来源: mdpi

【 摘 要 】

This work demonstrates how formation of strongly chemiluminescent 3-hydroxyphthalic hydrazide by hydroxylation of non-chemiluminescent phthalic hydrazide can be applied as a selective reaction probe to obtain information on authentic hydroxyl radical, i.e., ^•OH_aq, formation, in black light illuminated Degussa P25 TiO₂ aerated suspensions in the pH range from 3 to 11. The ^•OH_aq formation was found to be strongly pH dependent. At alkaline pH, the apparent quantum efficiency of ^•OH_aq formation was estimated to be at the ~10⁻² level whereas at acidic pH it was near zero. Addition of phosphate and fluoride ions substantially enhanced the ^•OH_aq production in the acidic pH range. It is suggested that ^•OH_aq-radical formation in TiO₂ photocatalysis can occur by oxidation of hydroxyl ions in the water layer adsorbed on TiO₂ surfaces.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.