Comparative study of CO adsorption on flat, stepped, and kinked Au surfaces using density functional theory

Our ab initio calculations of CO adsorption energies on low-Miller-index [(111) and (100)], stepped (211), and kinked (532) gold surfaces show a strong dependence on local coordination with a reduction in Au atom coordination leading to higher binding energies. We find trends in adsorption energies to be similar to those reported in experiments and calculations for other metal surfaces. The (532) surface provides insights into these trends because of the availability of a large number of kink sites which naturally have the lowest coordination (6). We also find that for all surfaces an increase in CO coverage triggers a decrease in the adsorption energy. Changes in the work function upon CO adsorption, as well as the frequencies of the CO vibrational modes, are calculated, and their coverage dependence is reported.