Screening the activity of Lewis pairs for hydrogenation of CO<sub>2</sub>

<p>CO<sub>2</sub> capture coupled with CO<sub>2</sub> conversion to hydrocarbon fuels could reduce the overall anthropogenic carbon footprint but requires an efficient catalytic pathway for CO<sub>2</sub> hydrogenation. In this work, we examine functional groups that can be integrated within nanoporous materials, such as metal organic frameworks, that could lead to the development of materials that can selectively adsorb CO<sub>2</sub> from flue gas and convert it into a useful fuel. We focus on the use of Lewis pair (LP) moieties as catalytic functional groups because of their activity for heterolytic dissociation of H<sub>2</sub> and subsequent hydrogenation of CO<sub>2</sub>. However, most LP functional groups also strongly bind CO<sub>2</sub>, such that the catalytic site can be poisoned if the binding energy of CO<sub>2</sub> is much stronger than that of H<sub>2</sub>. In this work, we screen a variety of LP moieties using density functional theory to compute the adsorption energies of H<sub>2</sub> and CO<sub>2</sub>. We consider five classes of LP functional groups, with each class designed to explore modifying the binding energies in different ways. We have developed a mathematical model for predicting the H<sub>2</sub> adsorption energies on various Lewis pairs as a function of geometric and energetic properties of the functional moieties.</p>