Synergistic PtPdNi Ternary Alloy Nanoparticles Confined in Hollow Carbon Spheres for Highly Efficient and Stable Styrene Hydrogenation.

Synergistic effects in multimetallic catalysts can dramatically enhance catalytic activity beyond that of their monometallic analogues. However, rationally designing multimetallic systems with precisely controlled composition, well-defined architecture, and high structural stability to fully exploit these synergistic interactions remains a formidable challenge. Here, we report hollow porous carbon spheres (HPCs) encapsulating PtPdNi ternary alloy nanoparticles (NPs) with tunable Pt/Pd/Ni ratios as highly active and recyclable catalysts for the hydrogenation of styrene to ethylbenzene. The catalytic performance of PtPdNi@HPCs strongly depends on composition, with the Pt/Pd/Ni = 1:1:1 sample exhibiting the highest activity under ambient conditions (25 °C, 0.1 MPa H2), surpassing all monometallic (Pt@HPCs, Pd@HPCs, Ni@HPCs), bimetallic (PtNi@HPCs, PdNi@HPCs, PtPd@HPCs), and other ternary analogues. This optimal catalyst also displays broad substrate scope, efficiently hydrogenating vinyl derivatives bearing electron-donating or -withdrawing substituents as well as linear alkenes. Combined experimental and characterization analyses attribute the superior performance to the synergistic interplay among Pt, Pd, and Ni atoms, where Ni incorporation promotes the formation of reactive adsorbed species, half-hydrogenated intermediates, and active hydrogen species. The protective carbon shell further ensures excellent stability and recyclability by preventing nanoparticle aggregation and leaching. This strategy offers a general route to design yolk-shell nanoreactors integrating multimetallic components for diverse catalytic transformations.