We studied adsorption of CO 2 on well-ordered thin CaO(001) films, prepared on Mo(001) and Pt(001) single-crystal surfaces in ultrahigh vacuum (UHV) conditions, using infrared reflection-absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). At low coverages, CO 2 adsorbs as monodentate carbonates (CO 3 2– ). TPD spectra showed pseudo-first-order desorption kinetics with a maximum shifting from 500 to 470 K with increasing CO 2 coverage. However, at further increasing exposures, desorption maximum is shifted to the considerably higher temperatures (570 K), although CO 2 uptake remained almost the same. This unusual effect was found to correlate with dissociative adsorption of residual water in the UHV background as observed both by TPD and IRAS. Comparative analysis of spectral evolution on crystalline CaO(001) films and CaO nanoparticles favors the model, where surface hydroxyls only affect adsorption geometry of the carbonates rather than form bicarbonate species. However, hydroxyls show stabilizing effect on CO 2 binding to the CaO surface.
No takes yet. Share an insight, caveat, or question.
Weng et al. (2018) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: