Spherical covalent organic framework supported Cu/Ag bimetallic nanoparticles with highly catalytic activity for reduction of 4-nitrophenol

Abstract

4-Nitrophenol (4-NP) is water pollutant with good stability, high toxicity and difficult degradation, which will cause great harm to the environment. Thus, the development of high efficiency and rapid catalysts for the degradation of 4-NP will be an urgent problem to be solved. Herein, we synthesized covalent organic framework supporting Cu/Ag bimetallic nanoparticles (Cu/Ag–COF), which had better catalytic activity for the reduction of 4-NP. The porous COF possess large surface area of approximately 737.8 ​m2/g, so it can provide abundant sites for loading metal nanoparticles. At the same time, COF could also improve the stability and catalytic effect of nanocatalyst under flexible condition. The prepared Cu/Ag–COF exhibited the higher catalytic reduction of 4-NP into 4-aminophenol (4-AP) under the condition that the molar ratio of NaBH4 to 4-NP was 147 and achieved an apparent rate constant of kCu/Ag–COF ​= ​0.0073 s−1. The apparent rate constant of Cu/Ag–COF was higher than that of Ag–COF (kAg-COF ​= ​0.0032 s−1) and Cu–COF (kCu-COF ​= ​0.0047 s−1), indicating that this system had a synergistic catalytic effect to improve the catalytic activity of metal nanoparticles. Moreover, Cu/Ag–COF still had good catalytic effect after eight cycles, which indicated that it had good stability and reusability. This work provides a novel strategy to fabricate COF supported nanoparticles for outstanding performance in treating wastewater containing 4-NP.