Converting metal–organic polyhedra to Pd single atoms on graphene for efficient selective semi-hydrogenation of alkynes

Selective hydrogenation of alkynes to alkenes is pivotal in the chemical industry. Pd-containing materials have been proven to be effective catalysts, while balancing the activity-selectivity trade-off remains a significant challenge. Here we report the fabrication of Pd single atoms from the conversion of metal–organic polyhedra (MOPs) for the first time. The MOP (M₆L₄), constructed from Pd salt and N-containing ligand, can interact with the graphene support via π-electron coupling, leading to well dispersion of MOP molecules. In subsequent thermal treatment, Pd is anchored by N-doped graphene formed in situ, producing single Pd atoms (denoted as Pd₁/G). The obtained Pd₁/G catalyst exhibits excellent activity (100% conversion) and styrene selectivity (94%) in the semi-hydrogenation of phenylacetylene under mild conditions (298 K, 1 bar H₂). Such performance is much superior to the counterpart catalyst Pd/G with Pd nanoparticles and the commercial Lindlar catalyst and is among the best of the reported catalysts for phenylacetylene semi-hydrogenation.