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

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 (O_CO2 ) 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 O_CO2 -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 O_CO2 -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 O_CO2 -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.