Room-Temperature Activation of H₂ by a Surface Frustrated Lewis Pair

Surface frustrated Lewis pairs (SFLPs) have been implicated in the gas-phase heterogeneous (photo)catalytic hydrogenation of CO₂ to CO and CH₃ OH by In₂ O_3-x (OH)_y . A key step in the reaction pathway is envisioned to be the heterolysis of H₂ on a proximal Lewis acid-Lewis base pair, the SFLP, the chemistry of which is described as In⋅⋅⋅In-OH + H₂ → In-OH₂ ⁺ ⋅⋅⋅In-H^- . The product of the heterolysis, thought to be a protonated hydroxide Lewis base In-OH₂ ⁺ and a hydride coordinated Lewis acid In-H^- , can react with CO₂ to form either CO or CH₃ OH. While the experimental and theoretical evidence is compelling for heterolysis of H₂ on the SFLP, all conclusions derive from indirect proof, and direct observation remains lacking. Unexpectedly, we have discovered rhombohedral In₂ O_3-x (OH)_y can enable dissociation of H₂ at room temperature, which allows its direct observation by several analytical techniques. The collected analytical results lean towards the heterolysis rather than the homolysis reaction pathway.