Rational synthesis of Pd dual-atom catalysts via molecular precursor engineering for selective hydrogenation

Abstract

Pd dual-atom catalysts (Pd DACs) demonstrate exceptional potential to balance conversion and selectivity in selective hydrogenation, while their rational design presents challenges. In this study, Pd DACs were successfully synthesized through molecular precursor engineering by the transformation of metal–organic polyhedra (MOPs). The MOP, Pd₄L₄, formed by Pd salts and N-containing ligands can effectively interact with graphene oxide (GO). This interaction ensures a good dispersion of Pd₄L₄ molecules. After heat treatment, Pd atoms are anchored to N-doped graphene, forming Pd-DAC. High angle annular dark field scanning transmission electron microscopy and X-ray absorption fine structure confirm the successful preparation of Pd DACs. In phenylacetylene semi-hydrogenation, Pd-DAC shows 100% conversion with 93% styrene selectivity owing to the synergistic effect of Pd–Pd bonds, outperforming the Pd nanoparticle catalyst Pd-NPC (50% selectivity) and the commercial Lindlar catalyst (54% activity). This catalyst is among the best reported catalysts for phenylacetylene semi-hydrogenation. Furthermore, Pd-DAC exhibits broad applicability in the selective hydrogenation of diverse alkynes to olefins. The rational synthesis of DAC provides insight into the generation of efficient catalysts.