Abstract

In this study, we explore the potential of metal–organic frameworks (MOFs) as catalysts for converting CO<inf>2</inf> into valuable chemicals. The focus is on integrating frustrated Lewis pairs (FLPs) within the UiO−67 framework. We investigated 12 distinct functionalized FLP moieties (X = −BF<inf>2</inf>, −BCl<inf>2</inf>, −BBr<inf>2</inf>, −BH<inf>2</inf>, −B(CH<inf>3</inf>)<inf>2</inf>, −B(CF<inf>3</inf>)<inf>2</inf>, −B(CN)<inf>2</inf>, −B(NO<inf>2</inf>)<inf>2</inf>, −B(OH)<inf>2</inf>, −B(NH<inf>2</inf>)<inf>2</inf>, −B(OCH<inf>3</inf>)<inf>2</inf>, and −B(N(CH<inf>3</inf>)<inf>2</inf>)<inf>2</inf> to determine their ability to activate small molecules within heterogeneous catalysis using density functional theory (DFT). This study reveals two critical stages in the CO<inf>2</inf> conversion process with H<inf>2</inf> in UiO−67−X. First, the initial heterolytic cleavage of H<inf>2</inf> at the FLP site, and second, the subsequent hydrogenation of CO<inf>2</inf>. The latter involves the addition of a hydride and a proton. Our findings demonstrate that these modifications facilitate efficient dissociation of H<inf>2</inf> into H^δ− and H^δ+ with energy barriers ranging from 0.12 to 0.87 eV and CO<inf>2</inf> hydrogenation barriers spanning from 0.61 to 1.90 eV. Notably, the −B(CH<inf>3</inf>)<inf>2</inf> functional group exhibited superior effectiveness in CO<inf>2</inf> hydrogenation to formic acid (HCOOH; FA). This enhanced activity correlates directly with FLP acidity and the Gibbs free energy changes in H<inf>2</inf> dissociation reaction. It highlights the significant influence of FLP−assisted heterolytic dissociation of H<inf>2</inf> in the CO<inf>2</inf> conversion process. The results of this study do more than introduce metal-free heterogeneous FLPs within MOFs. They also establish a clear link between the functional group composition, FLP acidity, and catalytic efficiency. These insights offer a valuable theoretical foundation for the design of advanced UiO−67−X catalysts. They open up possibilities for transforming greenhouse gases into valuable chemical products, contributing to sustainable chemical synthesis.