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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 30, Number 3
BKCSDE 30(3)
March 20, 2009 

Experimental Evidence of the Mobility of Hydroperoxyl/Superoxide Anion Radicals from the Illuminated TiO2 Interface into the Aqueous Phase
Bum Gun Kwon, Jeyong Yoon*
TiO2 photocatalyst, Hydroperoxyl/superoxide anion radical, Knotted tubing reactor, Chemiluminescence, MCLA
The understanding of behaviors of hydroperoxyl/superoxide anion radicals (HO2·/O2) generated from a photoirradiated TiO2 surface is essential to improve the efficiency of TiO2 photocatalytic reactions by decreasing the recombination of photoinduced electron-hole (e--h+) pairs. In contrast with previous studies, we found that HO2·/O2 generated on the surface of illuminated TiO2 particles are mobile. HO2·/O2 formed by the photocatalysis of TiO2 particles immobilized onto the inner surface of a coil-quartz tube were forced under a continuous flow through a knotted tubing reactor (KTR) and into the aqueous phase completely separated from the TiO2 particles, and were measured by a chemiluminescence (CL) technique using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[ 1,2-a]pyrazin-3-one (MCLA) as the reagent. The initial concentration of the HO2·/O2 stream entering the KTR was determined by its half-life (98 s) at pH 5.8. We suggests that the efficiency of TiO2 photocatalytic reactions may be further improved by utilizing the mobility of HO2·/O2.
667 - 670
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