Cu nanoparticles embedded in the porous organic polymer as highly effective catalysts for nitroaromatics reduction

The improvement of effective catalytic systems relies on the synthesis of catalytically active composites including metal nanocatalysts and porous supports. In particular, it is essential to develop porous composites comprising cheaper metal nanocatalysts rather than expensive noble metals. This study reports the preparation of covalent organic polymer (COP) as a support in the immobilization of Cu nanoparticles (NPs). Cu(II) species were successfully chelated to nitrogen and oxygen atoms in the COP by mixing with a copper (II) acetate solution. The as-prepared catalysts were distinguished using various methods, including XRD, FE-SEM, FT-IR, BET, EDX, and ICP-AES. The findings indicated that uniform Cu NPs were homogeneously and firmly embedded into the surface of COP. The final Cu–COP sample demonstrated efficient catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The activity factor (k') and rate constant (Kapp) of Cu–COP were respectively 9.65 s−1 and 0.0193 s−1 g−1 for 4-NP reduction and could completely transform 4-NP to 4-AP within 3 min. Furthermore, the conversion rate of the supported nanoparticles was 97.1% in 4-NP reduction up to five cycles with no decreased reactivity.