Design of Lewis Pair-Functionalized Metal Organic Frameworks for CO₂ Hydrogenation

Efficient catalytic reduction of CO₂ is critical for the large-scale utilization of this greenhouse gas. We have used density functional electronic structure methods to design a catalyst for producing formic acid from CO₂ and H₂ via a two-step pathway having low reaction barriers. The catalyst consists of a microporous metal organic framework that is functionalized with Lewis pair moieties. These functional groups are capable of chemically binding CO₂ and heterolytically dissociating H₂. Our calculations indicate that the porous framework remains stable after functionalization and chemisorption of CO₂ and H₂. We have identified a low barrier pathway for simultaneous addition of hydridic and protic hydrogens to carbon and oxygen of CO₂, respectively, producing a physisorbed HCOOH product in the pore. We find that activating H₂ by dissociative adsorption leads to a much lower energy pathway for hydrogenating CO₂ than reacting H₂ with chemisorbed CO₂. Our calculations provide design strategies for efficient catalysts for CO₂ reduction. (Chemical Equation Presented).