A Rapid, Sustainable, One-step Mechanochemical Strategy for Synthesizing Gold Nanoparticle-Doped Covalent Organic Frameworks.

Abstract

Doping gold nanoparticles within covalent organic frameworks (AuNPs@COFs) has garnered enormous momentum due to their unique properties and broad applications. Nevertheless, prevailing multi-step synthesis is plagued with low time efficiency, eco-unfriendliness, and tedious protocols. Herein, we introduce a rapid, sustainable, one-step mechanochemical strategy for synthesizing AuNPs-doped COFs via steel ball milling within an hour under ambient conditions. This approach overcomes the synthetic barriers of conventional multi-step methods, such as extended reaction times (5 days), the use of toxic solvents, elevated temperatures, and reliance on external reducing agents. One exemplary AuNPs@COF (AuNPs@DMTP-TPB) exhibits high crystallinity, porosity, small AuNP size, and uniform dispersion (5.4 ± 0.6 nm), surpassing its counterpart synthesized via multi-step solution-based methods (6.4 ± 1.1 nm). Control experiments suggest that the in situ formation of AuNPs is primarily attributed to the galvanic reduction of gold precursor by stainless steel. As a proof-of-concept catalytic application, AuNPs@DMTP-TPB demonstrates remarkable catalytic activity and recyclability for the aqueous reduction of 4-nitrophenol under ambient conditions. This study provides an environmentally benign and fast pathway to synthesize AuNPs@COFs via mechanochemistry for the first time, opening tremendous possibilities for heterogeneous catalysis and beyond.