Hexagonal BaTiO(3–x)H x Oxyhydride as a Water-Durable Catalyst Support for Chemoselective Hydrogenation

We present heavily H–-doped BaTiO(3‑x)H x (x ≈ 1) as an efficient and water-durable catalyst support for Pd nanoparticles applicable to liquid-phase hydrogenation reactions. The BaTiO(3–x)H x oxyhydride with a hexagonal crystal structure (P63/mmc) was synthesized by the direct reaction of BaH2 and TiO2 at 800 °C under a stream of hydrogen, and the estimated chemical composition was BaTiO2.01H0.96. Density functional theory calculations and magnetic measurements indicated that such heavy H– doping results in a metallic nature with delocalized electrons and a low work function. The potential of BaTiO(3‑x)H x as a catalyst support was examined for the selective hydrogenation of unsaturated C–C bonds by Pd nanoparticles deposited on BaTiO(3‑x)H x . We found that the turnover frequency for phenylacetylene hydrogenation per total amount of Pd in Pd/BaTiO(3‑x)H x was the highest among the supported Pd catalysts reported to date. The strong electronic charge transfer between Pd and the support, as confirmed by X-ray photoelectron spectroscopy measurements, can be attributed to be responsible for such high catalytic activity. The combination of the BaTiO(3‑x)H x support and Pd nanoparticles provides for the selective hydrogenation of unsaturated C–C bonds and highlights the validity of catalyst design that integrates H– in support materials.