Graphite-supported single copper catalyst for electrochemical CO2 reduction: A first-principles approach

First-principles study explores the catalytic performance of the Cu(1 1 1) and Cu/G catalysts for the electrochemical CO2 reduction using computational hydrogen electrode model. Two different pathways, determined based on the initially generated intermediates (COOH* and HCOO*), as well as successive intermediates and the end products, were investigated. Although the two catalysts promote both pathways, Cu(1 1 1) surface favors “COOH pathway” and Cu/G catalyst strongly promotes the “HCOO pathway” with an free energy barrier of 0.83 eV (CO* → CHO*) and 0.87 eV (HCOO* → H2COO*). Electronic properties and binding nature of the final intermediate (CH3O*) on both catalysts sheds light on the fundamental reason for the selective end products (CH4 on the Cu(1 1 1) surface and CH3OH on the Cu/G catalyst). CH3OH is predominantly produced with the Cu/G catalyst because the CO bond of CH3O* is stronger than the bond between the single Cu atom and O of CH3O*, given that the energy of the d-band center of the single Cu atom is relatively highly negative. The current study explores the different electrochemical reduction pathways on the Cu(1 1 1) and Cu/G catalyst, providing insight for the design of highly efficient catalysts that afford selective end products.