Synthesis of copper-based nanoparticles confined in a pyridine N-containing COF and their catalytic applications

The main challenge of using non-noble metal copper nanoparticles (Cu NPs) as catalysts is to find or prepare suitable support platforms to anchor Cu NPs, thereby avoiding the aggregation tendency owing to their high surface energy. In this study, a novel pyridine N-containing covalent organic framework (COF) was designed and used as a template for the confined growth of Cu NPs. The prepared imine-connected TAPB-PCBA had abundant one-dimensional ordered channels, moderate specific surface area and good stability. The skeleton structure of TAPB-PCBA contained a large number of evenly distributed pyridine N, which can act as the nucleation site for Cu NPs. The well-defined pore structure confines the growth of Cu NPs and makes them controllable in size. The pores in TAPB-PCBA are completely independent and isolated from each other, minimizing the accumulation of Cu NPs. With the help of these factors, ultrafine Cu/Cu2O composite NPs (2.5 nm) with narrow size distribution anchored inside the cavity of the TAPB-PCBA were successfully prepared. The as-prepared Cu-containing COF, Cu@TAPB-PCBA, showed excellent catalytic capacity for dye degradation and nitrophenol reduction under mild conditions and low catalyst loads, respectively. In addition, Cu@TAPB-PCBA also has a good recyclability, multiple use without significant loss of catalytic activity. We expect this COF-supported growth-confined preparation of metal NPs to further facilitate the design and preparation of non-noble metal NPs@COF composites, replacing noble metals in certain catalytic applications.