Activation of Carbon Dioxide on ZnO Nanoparticles Studied by Vibrational Spectroscopy
Noei, H. / Wöll, C. / Muhler, M. / Wang, Y. (2011)
J. Phys. Chem. C 115 (2011), 4, 908–914
- Date: 2011
Noei, H. / Wöll, C. / Muhler, M. / Wang, Y. (2011): „Activation of Carbon Dioxide on ZnO Nanoparticles Studied by Vibrational Spectroscopy“. In: J. Phys. Chem. C 115 (2011), 4, 908–914
The activation of CO2 on clean and hydroxylated ZnO nanoparticles has been studied by ultrahigh vacuum FTIR spectroscopy (UHV-FTIRS). Exposing the clean ZnO powder samples to CO2 at 300 K leads to the formation of a number of carbonate-related bands. A detailed assignment of these bands was carried out using isotope-substitution experiments with C18O2.
On the basis of vibrational and thermal stability data for ZnO single crystal surfaces, a consistent description of the interaction of CO2 with ZnO powder particles can be provided:
(1) on the mixed-terminated ZnO(101¯0) facets, a tridentate carbonate is formed;
(2) on the polar, O-terminated (0001¯) facets, a bidentate carbonate species is formed via CO2 activation at oxygen vacancy sites; and
(3) additional monodentate or polydentate carbonate species are formed at defect sites such as steps, edges, kinks, and vacancies.
The formation of carbonate-related vibrational bands is observed at an exposure temperature as low as 100 K, thus demonstrating the high activity of ZnO nanoparticles with regard to CO2 activation.