Porous TiO₂/Pt/TiO₂ sandwich catalyst for highly selective semihydrogenation of alkyne to olefin

The tailoring of metal-oxide interfaces is a powerful approach to enhance the catalytic efficiency of heterogeneous catalysts. However, the function of the metal. oxide interface is still not clearly understood in most catalytic processes. The construction of heterogeneous catalysts with single interface sites would be a straightforward way to reveal the interface effect. In this work, we introduced a simple strategy to synthesize a porous TiO₂/Pt/TiO₂ sandwich catalyst by atomic layer deposition. All Pt nanoparticles were covered by two porous TiO₂ layers in this sandwich structure, creating dominant Pt-TiO₂ interface sites. The TiO₂/Pt/TiO₂ sandwich catalyst shows good catalytic performance in the tandem ammonia.borane decomposition and semihydrogenation of various alkynes with high selectivity and stability. In contrast, the Pt nanoparticles without complete coverage of porous TiO₂ layers have a low selectivity in semihydrogenation of alkynes. The sandwich catalyst also exhibits high selectivity in hydrogenation of the -C=O bond of α,β-unsaturated aldehyde. The high selectivity of the TiO₂/Pt/TiO₂ sandwich catalyst can be ascribed to the electron-rich property of the Pt-TiO₂ interface sites, which favor the adsorption of alkyne with electrophilicity but inhibit the overhydrogenation of C=C bonds.