Date: February 22, 2012
Creator: Liu, Cong; Cundari, Thomas R., 1964- & Wilson, Angela K.
Description: This article discusses CO₂ reduction on transition metal (Fe, Co, Ni, and Cu) surfaces. Abstract: Reduction of CO₂ to CO on Fe, Co, Ni, and Cu surfaces has been studied using density functional theory (DFT) methods. Three reaction steps were studied: (a) adsorption of CO₂ (M + CO₂/M) (M = transition metal surface), (b) decomposition of CO₂ (CO₂/M = (CO + O)/M), and (c) desorption of CO ((CO + O)/M = O/M + CO). Binding energies and reaction energies were calculated using the generalized gradient approximation (GGA) via the Perdew-Burke-Ernzerhof (PBE) functional. Calculations show an interesting trend for reaction energies and total reaction barriers, as a function of metal: from Fe to Cu, reactions tend to be less exergonic; the metals earlier in the 3d series have lower total barriers for CO₂ reduction. However, "overbinding" of CO₂ on Fe causes a thermodynamic sink on the reaction coordinate, adn Co and Ni are more favorable in terms of a smaller fluctuation in reaction energies/barriers for these elementary catalytic steps. A Brønsted-Evans-Polanyi (BEP) relationship was analyzed for C-O bond scission of CO₂ on the metal surfaces. Heterogeneous catalysis is also compared with the homogeneous models using transition metal β-diketiminato complexes, showing that ...
Contributing Partner: UNT College of Arts and Sciences