Cysteamine-modified Pd sites in a covalent organic framework for the efficient electrocatalytic semi-hydrogenation of terminal alkynes

Abstract

Achieving selective alkyne hydrogenation under mild conditions is highly appealing. In this work, cysteamine-modified Pd-based COF (denoted as Pd–TpBpy/Cys COF) was prepared and used as a heterogeneous redox mediator for the electrocatalytic semi-hydrogenation of terminal alkynes with H₂O as a sustainable hydrogen source. Notably, Pd–TpBpy/Cys COF could enable the reaction to proceed at a more positive potential and enhance the catalytic selectivity, which was superior to that of the unmodified Pd-based COF. Mechanistic investigation indicated that the in situ-generated H* by H₂O electrolysis was the key intermediate, and the semi-hydrogenation reaction proceeded through a addition pathway. In addition, good recyclability of the Pd–TpBpy/Cys COF showed its promising application potential.