Fabrication of ZIF-67@MIL-125-NH2 nanocomposite with enhanced visible light photoreduction activity

Abstract

Selective photoreduction of nitrophenols comes important for synthesis of pharmaceutical intermediates. Nowadays, metal-organic frameworks (MOFs) play an important role in preparation of photocatalysts because MOFs make shift from using photocatalyst in UV to visible light and upgrade photocatalytic activity and selectivity. In the past, metal and metal oxide nanoparticles were doped physically or chemically into MOFs for enhancement of photocatalytic activity. In this work, for a first time, titanium based metal organic frameworks (MIL-125-NH2) was post-synthetically modified with different ratios of zeolitic imidazolate framework-67 (ZIF-67), the novelty comes from coating MOFs with MOFs. The crystallinity of the prepared nanocomposite photocatalyst (ZIF-67@MIL-125-NH2) was interpreted by X-ray diffraction (XRD). The optical properties of the composite were investigated using UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The morphology and particle size was identified by scanning electron microscopy (SEM) and Transmission electron microscope (TEM). The nanocomposite was used for selective photocatalytic reduction of nitro-phenols in visible light irradiation. The nanocomposite showed high photocatalytic activity beside selectivity compared with P25. The effects of reusability of the optimum nanocomposite photocatalyst were investigated.