TY - JOUR

T1 - FTIR and TPD analysis of surface species on a TiO2 photocatalyst exposed to NO, CO, and NO-CO mixtures

T2 - Effect of UV-vis light irradiation

AU - Mikhaylov, Ruslan V.

AU - Lisachenko, Andrei A.

AU - Shelimov, Boris N.

AU - Kazansky, Vladimir B.

AU - Martra, Gianmario

AU - Alberto, Gabriele

AU - Coluccia, Salvatore

PY - 2009/12/8

Y1 - 2009/12/8

N2 - As a continuation of our previous work on the kinetics of photocatalytic reduction of NO by CO on titaniumdioxide, interaction of a Degussa P-25 TiO 2 photocatalyst with NO, CO, and NO-CO mixtures at ambient temperature has been studied by FTIR and TPD. Only reversible weak adsorption of NO on surface Ti4+ ions is found to occur in the dark. UV-vis irradiation greatly enhances the NO adsorption on Ti4+ and yields N2O, NO-, NO2-, and NO 3-surface species. After irradiation of TiO2 in a CO atmosphere, IR bands of surface CO2-and CO 3-species appear in addition to a continuous IR absorption tail towards lower wavenumbers due to free carriers in the reduced semiconductor. When TiO2 is exposed to a equimolar NO-CO mixture, N2O and CO2-are formed without irradiation supposedly by the reaction 2 NO + 2 CO + O2-→ 2 CO2-+ N2O. Subsequent light irradiation is accompanied by the accumulation of NO-and Ti4 +...NO complexes. No TiO2 reduction occurs in this case. FTIR spectra show that NO-produced by the photoinduced adsorption of NO can be eliminated by the following reaction: NO-+ CO →hv CO2-+ (1/2) N2. It is believed that this reaction is a key step in the nitrogen production by the photocatalytic process. The data obtained enable us to refine the earlier proposed reaction mechanism and to directly prove some of its key steps.

AB - As a continuation of our previous work on the kinetics of photocatalytic reduction of NO by CO on titaniumdioxide, interaction of a Degussa P-25 TiO 2 photocatalyst with NO, CO, and NO-CO mixtures at ambient temperature has been studied by FTIR and TPD. Only reversible weak adsorption of NO on surface Ti4+ ions is found to occur in the dark. UV-vis irradiation greatly enhances the NO adsorption on Ti4+ and yields N2O, NO-, NO2-, and NO 3-surface species. After irradiation of TiO2 in a CO atmosphere, IR bands of surface CO2-and CO 3-species appear in addition to a continuous IR absorption tail towards lower wavenumbers due to free carriers in the reduced semiconductor. When TiO2 is exposed to a equimolar NO-CO mixture, N2O and CO2-are formed without irradiation supposedly by the reaction 2 NO + 2 CO + O2-→ 2 CO2-+ N2O. Subsequent light irradiation is accompanied by the accumulation of NO-and Ti4 +...NO complexes. No TiO2 reduction occurs in this case. FTIR spectra show that NO-produced by the photoinduced adsorption of NO can be eliminated by the following reaction: NO-+ CO →hv CO2-+ (1/2) N2. It is believed that this reaction is a key step in the nitrogen production by the photocatalytic process. The data obtained enable us to refine the earlier proposed reaction mechanism and to directly prove some of its key steps.

UR - http://www.scopus.com/inward/record.url?scp=71049130654&partnerID=8YFLogxK

U2 - 10.1021/jp906176c

DO - 10.1021/jp906176c

M3 - Article

AN - SCOPUS:71049130654

VL - 113

SP - 20381

EP - 20387

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 47

ER -