posted on 2022-01-19, 16:03authored byRulin Sun, Xinlu Liu, Xiao Chen, Li Che, Xueming Yang, Qing Guo
Ethyl
acetate (EA) production from sequential ethanol (EtOH) photooxidation
on a rutile(R)-TiO2(110) surface has been investigated
by the temperature-programmed desorption (TPD) method at 355 and 266
nm. Significant EA product is detected under 266 nm irradiation, which
is most likely to be formed via cross-coupling of primary dissociation
products, aldehyde (CH3CHO) and ethoxy groups. On the contrary,
EA formation at 355 nm is negligible. In addition, the initial rate
of EA formation from EtOH at 266 nm is nearly 2 orders of magnitude
faster than that at 355 nm. Quantitative analysis suggests that EA
formation from sequential EtOH photooxidation on R-TiO2(110) is strongly dependent on photon energy or the energy of hot
holes. This experimental result raises doubt about the traditional
photocatalysis model on TiO2 where charge carriers relax
to their respective band edges prior to charge transfer to adsorbates
during the photocatalytic process, leading to no dependence on photon
energy in TiO2 photocatalysis.