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 CH3OH by In2O3−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 CH3OH. 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 In2O3−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. Auf der Suche nach dem Schlüsselschritt: Die Ergebnisse von fünf Spektroskopietechniken, DRIFTS, XPS, 1H MAS NMR, EPR und UV/Vis‐NIR, bieten neue Einblicke in die Wechselwirkung von gasförmigem H2 mit nanostrukturiertem rhombischem In2O3−x(OH)y bei Raumtemperatur. Schlussfolgerungen aus den integrierten Informationen, die aus diesen analytischen Techniken gewonnen wurden, sprechen für einen Heterolysemechanismus und gegen eine Homolyse.