Synthesis of (Zn/Co)-based zeolite imidazole frameworks and their applications in visible light-driven photocatalytic degradation of Congo red

Abstract

Zinc/cobalt (Zn/Co)-based zeolite imidazole frameworks (ZIFs) with varying Zn/Co molar ratios from 0/10 to 10/0 were synthesized by a microwave-assisted method, and the resulting materials were characterized by x-ray diffraction (XRD), nitrogen adsorption–desorption isotherms, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and atomic absorption spectroscopy (AAS). The microwave-assisted approach required a very short synthesis time as well as yielded (Zn/Co)ZIFs with high specific surface areas (1637.3 m2 g−1). It was found that the introduction of zinc into ZIF-67 enhanced catalytic activity in visible-light region. (Zn/Co)ZIF with a Zn/Co molar ratio of 2/8 manifested an excellent photocatalytic degradation of Congo red (CGR). The kinetic model of photocatalytic degradation was proposed based on adsorption isotherms (Langmuir model) and a unimolecular reaction for the heterogeneous catalysis. Further, the reusability was also addressed.