Alternative Pathway of CO2 Hydrogenation by Lewis-Pair-Functionalized UiO-66 MOF Revealed by Metadynamics Simulations

The reaction between H-2 and CO2 catalyzed by an intramolecular frustrated Lewis pair, which is covalently bonded to a UiO-66 metal-organic framework (MOF), is considered in this work. Free energy surfaces (FESs) for this reaction are generated throughout finite-temperature density functional theory (DFT) metadynamics (MD) simulations. The simulated FESs indicate an alternative stepwise pathway for the hydrogenation of CO2. Furthermore, indications of weaker binding of CO2 than H-2 to the Lewis pair centers have been observed via metadynamics simulations. These findings were unknown from the results of static-DFT calculations, which proposed a concerted reduction of CO2. The results of the present work may influence the design of new efficient heterogeneous Lewis pair (LP)-functionalized MOFs to catalyze capture and conversion of CO2 to high-value chemicals.