| AVS 64th International Symposium & Exhibition | |
| Surface Science Division | Wednesday Sessions |
| Session SS+HC+NS-WeA |
| Session: | Dynamical Processes at Surfaces |
| Presenter: | Jiamei Quan, University of Tsukuba, Japan |
| Authors: | J.M. Quan, University of Tsukuba, Japan T. Kondo, University of Tsukuba, Japan T. Kozarashi, University of Tsukuba, Japan T. Mogi, University of Tsukuba, Japan J. Nakamura, University of Tsukuba, Japan |
| Correspondent: | Click to Email |
Catalytic conversion of CO2 into valuable fuels and chemicals such as methanol, especially if activated by a precise energetic control, represents a potentially economic strategy for utilization of fossil feedstock and reducing CO2 emissions and their contributions to climate changes. The formation of formate intermediates (2CO2 + H2 → 2H COOa) on Cu catalysts is an important initial step, in which the reaction probability is reported as low as 10− 12 at 340 K.[1] Our previous reports suggested that the reaction proceeds via an Eley-Rideal type mechanism, where CO2 directly reacts with pre-adsorbed H to form HCOOa.[2] Recently, we have clarified using supersonic molecular beam apparatuses that the reaction probability is promoted up to ~10-3 by increasing both translational and vibrational energies, while insensitive to the Cu surface structure (Cu(111) and Cu(100)) and the surface temperature (120 - 210K). The energy efficacy on the reaction probability is found to be larger as much as 100 times for the vibrational energy compared to the translational energy, suggesting that the vibrational excitation significantly enhances the formate formation. Based on the comparison with DFT calculations, we conclude that the excitation of the bending mode of CO2 at the transition is crucially important to form the C-H bond of HCOO via lowering LUMO level of CO2. The small pre-exponential factor derived by the experiment is ascribed to the preferential orientation of the CO2 molecule (C-end collision to Ha on Cu) for the reaction. The discovered thermal non-equilibrium channel in CO2 conversion, which doesn’t require the heating of catalysts, is expected to provide a prototypical surface reaction dynamics and open up novel industrial pathways of efficient CO2 conversion into useful chemicals and fuels.
[1] (a) T. Fujitani, J. Nakamrua et al., App. Surf. Sci. 121–122 (1997) 583; (b) H. Nakano, J. Nakamrua et al., J. Phys. Chem. B 105 (2001) 1355.
[2] (a) J. Quan, J. Nakamrua, et al., Angew. Chem. Int. Ed. 56 (2017) 3496; (b) G. Wang, J. Nakamura, et al., J. Phys. Chem. B 110 (2005) 9.