Res. Chem. Intermed.
, Vol. 29, No. 2, pp. 125– 135 (2003)
Also available online - www.vsppub.com
The origin of the decline in the photocatalytic activity
in the decomposition of NO: TPD spectra
of the adsorbed NO species
YUN HU, JINLONG ZHANG
, MADOKA MINAGAWA,
TERUKAZU AYUSAWA, MASAYA MATSUOKA, HIROMI YAMASHITA
and MASAKAZU ANPO
Department of Applied Chemistry, Osaka Prefecture University 1-1 Gakuen-cho, Sakai,
Osaka 599-8531, Japan
Received 15 October 2002; accepted 19 December 2002
Abstract—In order to investigate the cause of the decline in the photocatalytic activity of TiO
the decomposition of NO in a ow reaction system, detailed TPD measurements of the photocatalysts
were carried out after the photoreactions. It was found that the TPD peak assigned to the adsorbed NO
species observed at around 524 K is directly associated with a decline in the photocatalytic activity.
The TPD spectrum of the adsorbed NO species consisted of three different types of species. The
° -adsorbed species of NO, formed under UV irradiation on the active surface sites, was found to
cause a remarkable decline in the photocatalytic activity of TiO
. It was also found that this decline
could be recovered to its original activity by heat treatment with Ar and /or O
at around 573 K.
: Photocatalytic activity; decomposition of NO; ow reaction system; TPD; decline of
Nitrogen oxides (NO
) are extremely toxic air pollutants emitted largely from the
reaction of N
in high temperature combustion processes, which cause
acid rain, photochemical smog and the formation of peroxy acetyl nitrates. The
importance and urgency of environmental protection has provoked many efforts in
developing new deNO
-ing catalytic technologies [1– 6]. One of the most desirable
Present address: Institute of Fine Chemicals, East China University of Science and Technology,
Shanghai 200237, P. R. China.
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