Feasible preparation of preferentially oriented (111) Pd nanocrystals supported on cyano-COFs for ultrahigh activity in C-C cross-couplings

Abstract

It is much challenging to synthesize highly dispersed noble metal nanocrystals (MNCs) and prevent their aggregation during the catalytic cycles. Choosing suitable solid supports to mediate the growth of MNCs can provide stable yet ultra-highly active heterogenous catalysts. However, very few studies have provided the controllable preparation of ultrafine MNCs. Herein, cyano-functionalized covalent organic frameworks (cyano-COFs)-mediated ultrafine preferentially oriented (111) PdNCs with particle diameter of 2.88 ± 0.60 nm were easily prepared in MeOH without any other external reducing agent. The obtained Pd/cyano-COFs presented ultrahigh activity in Suzuki-Miyaura couplings, with TOF of 2578 h−1 and chemo-selectivity of > 99 % for the cross-coupling between p-iodotoluene and phenylboronic acid at room temperature in the air. Furthermore, outstanding catalytic performance of Pd/cyano-COFs was found in Heck couplings as well. This study provides a new idea for the controllable preparation of metallic nanomaterials with high performance, which could facilitate the research on the regulation of catalytic performance by the chemical composition of supports.