The reactivity of NO on rutile TiO2(110)-1�1 surface was systematically investigated using temperature-programmed desorption (TPD) to understand the role of oxygen vacancies (VO's) in NO reduction.  For this purpose, we compared two TiO2(110)-1�1 surfaces with (r-TiO2(110)) and without (p-TiO2(110)) oxygen vacancies. The vacancy concentration was carefully characterized by the integrated area of the 500 K-H2O desorption peak in H2O TPD and was measured to be about 5 % for r-TiO2(110).  Our NO TPD results indicate that NO is reduced to N2O and N2 on both TiO2(110) surfaces with three distinct desorption peaks up to the substrate temperature of 400 K.  N2O desorption peak maxima are found to appear at 180 K, 270 K and 415 K, while N2 desorption peak is only resolved at 270 K.  Interestingly, our results further indicate that the integrated amount of reaction products such as N2O and N2 from NO is higher on r-TiO2(110) than on p-TiO2(110).  Although the detailed mechanism of NO reduction on TiO2(110) is still unclear, our results generally suggest that the defects such as oxygen vacancies and Ti3+ interstitials on r-TiO2(110) surface interact preferentially with NO to enhance the yield of reduction into N2O and N2.

Role of oxygen vacancies on NO reduction on rutile TiO<sub>2</sub>(110)-1[times]1

243rd National Meeting (2012)

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Role of oxygen vacancies on NO reduction on rutile TiO2(110)-1[times]1

Role of oxygen vacancies on NO reduction on rutile TiO₂(110)-1[times]1