| AVS 66th International Symposium & Exhibition | |
| Surface Science Division | Monday Sessions |
| Session SS+HC-MoA |
| Session: | CO2, CO, Water, and Small Molecule Chemistry at Surfaces |
| Presenter: | Johan Gustafson, Lund University, Sweden |
| Authors: | J. Gustafson, Lund University, Sweden B. Hagman, Lund University, Sweden A. Posada-Borbón, Chalmers University of Technology, Sweden A. Schaefer, Chalmers University of Technology, Sweden M. Shipilin, Stockholm University, Sweden C. Zhang, Lund University, Sweden L.R. Merte, Malmö University, Sweden A. Hellman, Chalmers University of Technology, Sweden E. Lundgren, Lund University, Sweden H. Grönbeck, Chalmers University of Technology, Sweden |
| Correspondent: | Click to Email |
CO2 chemistry has received significant attention recently, due to the greenhouse effect of CO2 emissions and the resulting climate change. CO2 reduction reactions, such as methanol synthesis and reverse water-gas shift, provide routes for recycling of CO2 and thus limiting the CO2 emissions. These reactions are commonly performed over Cu-based catalysts, making the interaction of CO2 and Cu, on the atomic scale, of importance for a fundamental understanding and the development of new and more efficient catalysts.
We have previously studied the dissociative adsorption of CO2 on Cu(100) using APXPS and DFT. In summary, exposure of the Cu surface to CO2 in the mbar range at temperatures above room temperature results in dissociation of CO2 into CO, that desorbs, and O that stays on the surface. The rate of the increase in O coverage, however, was not consistent with what one would expect from adsorption on the flat Cu(100) surface. Instead, we propose a model where the dissociation happen at atomic steps. The steps were found to both lower the activation barrier for the dissociation and separate the products, such that the probability for recombination is lowered.
As an obvious follow-up of this study, we have studied the dissociative adsorption of CO2 on Cu(911), which exposes five atoms wide (100) terraces separated by monatomic steps. In contrast to what we expected, the O coverage did not increase significantly faster on this stepped surface. Our preliminary analysis suggests that diffusion of O from one step to another reduces the effect of the steps separating O and CO, but also that the steps facilitate O diffusion to the subsurface region and possibly stabilisation of CO2 or CO3 species on the surface.
In this presentation we will report how we conclude that the steps control the dissociation and, especially, the present status of the studies of Cu(911).