Surface Analogues of Molecular Frustrated Lewis Pairs in Heterogeneous CO₂Hydrogenation Catalysis

The discovery of homogeneous, solution-based molecular frustrated Lewis pairs, denoted FLPs, comprising main-group elements that can activate H2 heralded a paradigm shift in chemistry and catalysis. In FLPs, unquenched Lewis base and Lewis acid sites (B···A) are able to polarize and dissociate H2 heterolytically to form adjacent proton and hydride sites (BH–···AH+), which can enable reactions such as CO2 reduction. In this paper, we draw attention to a relationship between these well-known molecular FLPs and the surface active sites comprised of proximal Lewis base and Lewis acid pairs, which have been reported multiple times in the literature to be responsible for driving various heterogeneous catalytic reactions. From our recent studies that described one such surface site in a nanostructured defect laden indium oxide, capable of activating H2 and enabling the hydrogenation of CO2, it was conjectured that these sites are surface FLPs. Significantly, the conversion rate for this hydrogenation reaction is...