CO2 Reduction on Transition Metal (Fe, Co, Ni, and Cu) Surfaces: In Comparison with Homogeneous Catalysis

• Published in: Journal of physical chemistry. C Vol. 116; no. 9; pp. 5681 - 5688
• Main Authors: Liu, Cong, Cundari, Thomas R, Wilson, Angela K
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 08.03.2012
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Surface physical chemistry; Total energy; Adsorption; Binding energy; Carbon dioxide; Density functional method; Generalized gradient approximation; Desorption; Transition metal; Catalysis; Energy barrier
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp210480c

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 = 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, and 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 both heterogeneous and homogeneous catalysis of CO2 reduction display the same energetic trend as a function of metal.