Figure 4: Catalytic carbon monoxide oxidation.
(a) Calculated adsorption energies for CO and O2 molecules on the pit-surrounding Ce sites (P1~P3) and on-surface Ce sites (S1~S3), and (b) calculated activation energies for O2 dissociation on the adjacent Ce sites of ultrathin CeO2 sheets with numerous pits; the coordination numbers of P1, P2, P3, S1, S2 and S3 are 5, 4, 6, 6, 6 and 6, respectively. (c) Overhead and top views of schematic structures for the three-atom-thick CeO2 sheets with a pit size of 0.90 nm × 0.82 nm (This size is fairly consistent with that statistically calculated from the HRTEM image in Fig. 2b); the CO molecules prefer to adsorb at P2 site, while the O2 molecules tend to adsorb and dissociate at the adjacent P1 sites. (d) Catalytic activity for CO oxidation versus reaction temperatures (experimental error: ±3%) and (e) the corresponding Arrhenius plot for the three CeO2 samples (experimental error: ±3%).
