Electrodeposition of Copper nanoparticles on Covalent Organic Framework and its role as heterogeneous catalyst for Ullmann reaction

Abstract

Covalent Organic Framework (COF) is a new class of porous materials whose porosity can be modified and predetermined. The synthetic control over structural design allows using COF for various applications. Its high surface area ordered pore structure and low density makes it a suitable material for heterogeneous catalysis. COF pores functionalized with heteroatoms can stabilize the incorporated metal nanoparticle and can work as heterogeneous catalysts. Herein, we report the bulk scale synthesis of IISERP-COF15 and electrochemical loading of Cu nanoparticles into the COF pore by cyclic voltammetry. We achieved a copper loading of 3.34 wt.% and found that the loaded copper is Cu0. The COF showed adsorption of 16 mmol/g whereas the copper loaded one showed 8 mmol/g. The synthesized Cu@COF was used as a catalyst for the Ullmann C-O bond formation reaction. The turnover number for the other reported catalysts are approximately 50-100. Our catalyst shows high activity with a very low catalyst loading of 0.25 mmol% and obtained a turnover number around ∼ 300 -350 and turnover frequency ∼15-17. The recyclability of COF has been proved up to 3 cycles. There has been a slight compromise on the crystallinity of COF after catalysis, but the chemical bonds are intact.