CO oxidation mediated by Al-doped ZnO nanoclusters: A first-principles investigation

Using density functional theory computations, the reaction pathways of CO oxidation mediated by Al-doped Zn12O12 cluster and its assembled wire-like (Zn12O12)(n=2-4) structures were studied. It is revealed that O-2 molecule is chemisorbed over the doped clusters while physisorbed over pristine (Zn12O12)(n). Moreover, increasing the size of the nanocluster from AlZn11O12 to (AlZn11O12)(4) enhances the O-2 adsorption energy, although the amount of increase reduces as the cluster size grows. The adsorption energies of O-2 over Al-doped (Zn12O12)(n) clusters range from -1.83 to -2.14 eV, which are more negative than those of CO molecule (approximate to-0.80 eV). The Eley-Rideal (ER) and Langmuir-Hinshelwood (LH) pathways are used to investigate the oxidation mechanisms of the CO molecule. The energy barriers for the rate limiting step in the LH mechanism (i.e., OCOO -> CO2 + O-ads) are around 0.30 eV, which are substantially lower than the energy barriers in the ER process.

Automated summary

Density functional theory computations were used to study the reaction pathways of CO oxidation mediated by Al-doped Zn12O12 cluster and its assembled wire-like structures. It was found that O-2 molecule is chemisorbed over doped clusters and physisorbed over pristine clusters, with the adsorption energy being more negative for the doped clusters. The Eley-Rideal and Langmuir-Hinshelwood pathways were used to investigate the oxidation mechanisms of the CO molecule, with lower energy barriers observed for the rate limiting step in the Langmuir-Hinshelwood mechanism.