Engineering electrophilic atomic Ir sites on CeO2 colloidal spheres for selectivity control in hydrogenation of α,β-unsaturated carbonyl compounds

Selective hydrogenation of the carbonyl bond in α,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects. Here, we demonstrate a facile emulsion-based molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO 2 spheres (Ir 1 @CeO 2 ). When applied to the hydrogenation of α,β-unsaturated aldehydes, Ir 1 @CeO 2 catalyst remarkably exhibited ~ 100% selectivity towards unsaturated alcohols, whereas the formation of Ir nanoparticles on CeO 2 drastically decreased the selectivity for unsaturated alcohols. Spectroscopic studies revealed that strong metal—support interactions triggered the charge transfer from Ir to CeO 2 , leading to the partial reduction of Ce 4+ to Ce 3+ along with the formation new Ir δ+ —O 2− —Ce 3+ (O V ) interfaces. The electrophilic atomic Ir species at the Ir δ+ —O 2− —Ce 3+ (O V ) interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.