Monodisperse Pd Nanotetrahedrons on Ultrathin MoO3–x Nanosheets as Excellent Heterogeneous Catalyst for Chemoselective Hydrogenation Reactions

Two-dimensional (2D) metal oxides are ideal host supports for constructing active hybrid catalysts in various organic reactions as they have large specific surface area, strong adsorption ability, and excellent thermal stability, which could serve as support and promoter to anchor noble metal nanoparticles with enhanced catalytic activity. Herein, a simple one-pot wet-chemical approach is developed for the synthesis of well-defined monodisperse Pd nanotetrahedrons on ultrathin MoO3–x nanosheets (Pd/MoO3–x ). Novel 2D oxygen-deficient MoO3–x nanosheets are formed in the synthetic process, which can work as robust catalyst support. Furthermore, in situ growth route is beneficial for boosting chemical attachment and electronic communication between Pd nanotetrahedrons and MoO3–x nanosheets. Such a composite system that combines the advantages of electronic effect and strong metal–support interaction contributes to excellent performance for selective hydrogenation of α,β-unsaturated aldehydes with high conversion (97%) and selectivity (96%) to its saturated aldehydes. Catalytic activity of Pd/MoO3–x nanocatalysts is improved through electronic structure regulation of Pd nanocrystals via electron-donating effect of oxygen vacancies in MoO3–x nanosheets. The high catalytic activity of our obtained hybrid catalysts associated with a synergy of electronic effect and strong metal–support interaction inspires the future exploration for other 2D oxides as functional supports to fabricate hybrid nanocatalysts for selective hydrogenation of α,β-unsaturated aldehydes.