Computational density functional theory study on the selective conversion of CO2 to formate on homogeneously and heterogeneously mixed CuFeO2 and CuO surfaces

Abstract

This study examines the reaction pathways for the selective conversion of CO2 to formate on the surface of mixed CuFeO2 and CuO (CFO) by employing density functional theory (DFT) calculation of the reaction energy and activation energy barrier. Two different systems were employed to model the CFO structure: homogeneous structures (HMS) of uniformly mixed 40% CuFeO2 (012) and 60% CuO (111), and a heterogeneous structure (HTS) created with CuO (111) clusters intermittently supported on the CuFeO2 (012) surface. The monodentate and bidentate oxygen coordinations (OCO2) in possible CO2 adsorption configurations were investigated for the preferential reduction of CO2 to formate on the surface Cu sites constrained by dense electron density. In the OCO2-monodentate configuration, the reaction energy and activation barrier for formate formation using PBE + D3 were ?0.41 eV and 0.28 eV, respectively, for the HTS and ?0.69 eV and 0.72 eV, respectively, for the HMS. In the OCO2-bidentate configuration, the corresponding values were ?0.58 eV and 0.53 eV, respectively, for the HTS and ?1.17 eV and 0.54 eV, respectively, for the HMS. Consequently, the conversion of CO2 to formate in the OCO2-monodentate mode was kinetically more advantageous in the HTS. This result indicated that the heterogeneity of the CFO structure, as well as the CO2 adsorption configuration, would change the rate-limiting energy barrier through the reaction coordinates, ultimately supporting the selective conversion of CO2 on HTS. - 2018 Elsevier B.V.