Photochemistry of 2-Propanol on Rutile TiO₂(110)

Abstract

2-Propanol is a typical volatile organic compound in air; the mechanistic studies of 2-propanol photodegradation on TiO 2 are important for the development of efficient photocatalysts.Here, we report a systematic study of 2-propanol photodecomposition on rutile (R)-TiO 2 (110) using the temperatureprogrammed desorption method. Under 355 nm irradiation, the formation of acetone ((CH 3 ) 2 CO) is clearly detected on reduced R-TiO 2 (110). The photoreactivity of molecular 2-propanol is much lower than that of 2-propoxy groups. As the surface temperature increases from 90 to 200 K, the yield of (CH 3 ) 2 CO production is markedly enhanced by 7 times, which is most likely due to the shift of 2-propanol molecules into dissociated 2-propoxy groups at higher surface temperature. Furthermore, the additional steric hindrance from the two methyl groups of 2-propanol may also inhibit the formation of suitable structures for 2-propanol dissociation on R-TiO 2 (110) at high 2-propanol coverage, thus lowering the yield of (CH 3 ) 2 CO formation. The results provide a fundamental insight into secondary alcohol photochemistry on TiO 2 .