Bulky nanodiamond-confined synthesis of sub-5 nanometer ordered intermetallic Pd₃Pb catalysts

Modulation of geometric and electronic structures of supported Pd-based catalysts by forming atomically ordered intermetallic phases enables an effective way to optimize catalytic performance. However, the synthesis of small-sized Pd-based intermetallic nanoparticle catalysts with improved mass-based activity remains formidable challenges, since high-temperature annealing generally required for atom ordering inevitably leads to severe metal sintering and thus large crystallites. Here, we present a bulky nanodiamond-confined method to prepare sub-5 nm Pd₃Pb intermetallic nanocatalysts by mitigating metal sintering at high temperatures, which is induced by the electronic interactions between metal and defect-rich graphene shells reinforced by diamond cores in the bulky nanodiamond support. The prepared small-sized Pd₃Pb intermetallic catalyst displays a high activity with a turnover frequency of 932 h⁻¹ for the semihydrogenation of phenylacetylene under mild conditions (room temperature, 3 bar H₂), along with a high selectivity of > 96% to styrene near the complete conversion of phenylacetylene.