Wavelength-Dependent Activity of Oxygen Species in Propane Conversion on Rutile TiO₂(110)

Photocatalytic oxidative dehydrogenation of propane (C₃H₈) into propene (C₃H₆) under mild conditions holds great potential in the chemical industry, but understanding how active species participate in C₃H₈ conversion remains a significant challenge. Here, the wavelength-dependent activities of bridging oxygen (O_b^2-) and the Ti_5c-bound oxygen adatom (O_Ti^2-) of model rutile (R) TiO₂(110) in C₃H₈ conversion have been investigated. Under 257 and 343 nm irradiation, hole-trapped O_Ti^- and O_b^- can abstract the hydrogen atom of C₃H₈, forming the CH₃CH^•CH₃ radical and C₃H₆. However, the rate of C₃H₈ conversion with hole-trapped O_b^- is strongly dependent on the wavelength, primarily producing the C₃H₇^• radical. In the case of hole-trapped O_Ti^-, C₃H₆ is the main product, which is nearly independent of wavelength. The differences in the wavelength-dependent activity and product selectivity are likely due to dynamic control rather than thermodynamic control. The result provides a deeper understanding of the dynamic processes involved in the conversion of light alkanes in TiO₂ photocatalysis.