(504e) Elucidating the Role of Oxygen Coverage in CO2 Reduction on Mo2C

Molybdenum carbide (Mo₂C) is a promising and low-cost catalyst for the conversion of CO₂ to CO. However, the underpinning mechanism occurring on the catalyst surface and the surface characteristics of Mo₂C catalyst under the reaction conditions are still elusive. In this study, we employ first principles calculations to understand the CO₂ dissociation mechanism on β-Mo₂C (001) under different oxygen coverage on the catalyst surface (oxycarbide).^{1, 2} Our results demonstrate that with increasing oxygen coverage, there is an electronic modification on the catalyst surface (e.g. d-band shift on Mo atoms), that in turn, tunes the interactions of the adsorbates and the CO₂ dissociation barriers. Interestingly, we reveal linear relationships between the oxygen coverage and electronic modification with the reactivity of the catalyst. We show that CO₂ can adsorb and dissociate on the oxygen covered Mo₂C surface, even in the presence of surface oxygen up to 0.5 monolayer (ML). Our results rationalize a series of experimental observations.

References:

1. M. Dixit, X. Peng, M. D. Porosoff, H. D. Willauer and G. Mpourmpakis, Cat. Sci. Tech., 2017, 7, 5521-5529.
2. M. D. Porosoff, J. W. Baldwin, X. Peng, G. Mpourmpakis and H. D. Willauer, ChemSusChem, 2017, 10, 2408-2415.