Pt-O4 moiety induced electron localization toward In2O-Triggered acetylene Semi-Hydrogenation

• Pt-O 4 -In 2 O ensemble site for superior acetylene semi-hydrogenation. • Increased electron localization surrounding with Pt-O 4 moiety in the ensemble site. • Enhanced heterolytic dissociation of H 2 on Pt-O 4 -In 2 O ensemble site. • Favorable formation of oxygen vacancy on the Pt 1 -In 2 O 3 catalyst. Transition metal oxides are emerging as promising catalysts for selective hydrogenations, but elaborating oxides catalysts with excellent hydrogenation activity remains challenging, especially at atomic level. Here, we report a theoretical-guided atomic design strategy with experimental verification to fabricate an excellent In 2 O 3 -based catalyst with an Pt-O 4 -In 2 O ensemble site for acetylene semi-hydrogenation. Theoretical calculations reveal that the presence of Pt-O 4 moiety in the ensemble site increases the electron localization surrounding with the moiety and thus strengthens the frustrated Lewis pair of In-O within the In 2 O site adjacent to the moiety. These structure features contribute to a promoted activation of hydrogen on the ensemble site via heterolytic dissociation and enhanced acetylene semi-hydrogenation on the oxygen vacancy adjacent to the Pt-O 4 moiety. The Pt 1 -In 2 O 3 catalyst featured with the ensemble site was synthesized by atomic layer deposition technology and characterized by multiple technologies, including atomic-resolution electron microscopy, X-ray absorption spectroscopy, and H 2 -D 2 exchange experiments, to validate the theoretical predictions. As expected, the experimental results elucidate an enhanced activation of hydrogen, and a full conversion of acetylene with 91% of ethylene selectivity on the Pt 1 -In 2 O 3 catalyst, which is remarkably higher than those of the pristine In 2 O 3 catalyst.