Graphdiyne-based Pd single-atom catalyst for semihydrogenation of alkynes to alkenes with high selectivity and conversion under mild conditions

Abstract

The development of efficient heterogeneous catalysts for alkyne hydrogenation with high activity and selectivity is highly desirable and yet remains a great challenge. Herein, a Pd single-atom catalyst (Pd^s–GDY) is prepared using graphdiyne as support, and used in the semihydrogenation of alkynes. As a proof of concept, the Pd^s–GDY exhibits a high activity for the semihydrogenation of phenylacetylene under mild reaction conditions, with a TOF of 6290 h⁻¹, and a selectivity of 99.3% at 100% conversion, both much higher than those of the counterparts comprising Pd nanoparticles (NPs), namely, Pd^NP1–GDY (with 2 nm Pd NPs) and Pd^NP2–GDY (with 12 nm Pd NPs). In addition, after the full conversion of phenylacetylene, Pd^s–GDY could still maintain a selectivity as high as 98.9% towards styrene, with almost no phenylethane produced even with a prolonged reaction time; in contrast, for Pd^NP1–GDY and Pd^NP2–GDY, within the same reaction time, the selectivity decreases dramatically to 66.6% and 8.5%, respectively. Infrared spectroscopy reveals that Pd^s–GDY features the weakest adsorption to styrene, which is responsible for its high performance. This work provides an effective strategy to rationally design Pd catalysts for semihydrogenation of alkynes to alkenes with desirable activity and selectivity.