Catalysts 2013, 3(2), 418-443; doi:10.3390/catal3020418
Article

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

Received: 16 December 2012; in revised form: 23 January 2013 / Accepted: 22 March 2013 / Published: 16 April 2013
(This article belongs to the Special Issue Photocatalysts)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: 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., OHaq, formation, in black light illuminated Degussa P25 TiO2 aerated suspensions in the pH range from 3 to 11. The OHaq formation was found to be strongly pH dependent. At alkaline pH, the apparent quantum efficiency of OHaq 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 OHaq production in the acidic pH range. It is suggested that OHaq-radical formation in TiO2 photocatalysis can occur by oxidation of hydroxyl ions in the water layer adsorbed on TiO2 surfaces.
Keywords: photocatalysis; TiO2; OHaq radical; chemiluminescence
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MDPI and ACS Style

Liao, H.; Reitberger, T. Generation of Free OHaq Radicals by Black Light Illumination of Degussa (Evonik) P25 TiO2 Aqueous Suspensions. Catalysts 2013, 3, 418-443.

AMA Style

Liao H, Reitberger T. Generation of Free OHaq Radicals by Black Light Illumination of Degussa (Evonik) P25 TiO2 Aqueous Suspensions. Catalysts. 2013; 3(2):418-443.

Chicago/Turabian Style

Liao, Haidong; Reitberger, Torbjörn. 2013. "Generation of Free OHaq Radicals by Black Light Illumination of Degussa (Evonik) P25 TiO2 Aqueous Suspensions." Catalysts 3, no. 2: 418-443.

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