Low-Temperature C-H Bond Activation via Photocatalysis: Highly Efficient Ethylbenzene Dehydrogenation into Styrene on Rutile TiO2(110)

The direct dehydrogenation of hydrocarbons to olefins under mild conditions is an atom-economical but challenging route. Here, we have investigated photocatalytic ethylbenzene dehydrogenation into styrene on rutile(R)-TiO2(110) using the temperature-programmed desorption (TPD) method. The results demonstrate that photocatalytic ethylbenzene dehydrogenation into styrene occurs on R-TiO2(110) in a stepwise manner, in which the initial alpha-C-H bond cleavage occurs facilely under UV irradiation via a possible homolytic hydrogen atom transfer process and then is followed by the second C-H bond cleavage induced by either photocatalysis at similar to 120 K or thermocatalysis at >400 K. With preadsorbed oxygen atoms to eliminate hydrogen atoms from ethylbenzene dehydrogenation and excess electrons on the surface, the yield of styrene is largely enhanced by about 4 times. The results not only demonstrate a photocatalytic route for ethylbenzene dehydrogenation into styrene on R-TiO2(110) but also advance our understanding of the photocatalytic activation of the saturated C-H bond with TiO2.

Automated summary

In this study, the photocatalytic dehydrogenation of ethylbenzene into styrene on R-TiO2(110) was investigated using the temperature-programmed desorption method. The results showed that the reaction proceeded stepwise, with the initial alpha-C-H bond cleavage occurring under UV irradiation and the second C-H bond cleavage induced by either photocatalysis or thermocatalysis. The addition of oxygen atoms and excess electrons on the surface greatly enhanced the yield of styrene.