Catalytic Activity of Cu‐MOF Catalyst for 4‐Nitrophenol Reduction
Y.M. Hunge, A.A. Yadav, Sutripto Majumder, Kai Takagi, Tayyab Ali, Akira Fujishima, Chiaki Terashima
Abstract
Abstract Nitroaromatic compounds are widely used in various industries, including dye manufacturing, leather processing, plastics, fungicides, pesticides, insecticides, pharmaceuticals, and paper production. However, specific nitrophenols such as para‐nitrophenol are recognized as hazardous environmental pollutants. Therefore, their removal or conversion into less harmful compounds, such as 4‐aminophenol is of paramount importance. In this study, a copper‐based metal–organic framework (Cu‐BDC MOF) was synthesized via a simple, cost‐effective hydrothermal method at different deposition temperatures. The synthesized materials were characterized using techniques such as X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Cu‐BDC MOF, which exhibited a square plate‐like morphology served as an efficient catalyst for the reduction of 4‐nitrophenol to 4‐aminophenol. Sodium borohydride (NaBH₄) was employed as the reducing agent in conjunction with the Cu‐MOF catalyst. An increase in the concentration of NaBH₄ enhanced the catalytic performance by supplying more BH₄ − ions, which act as electron donors in the reduction reaction. The 4‐NP reduction reaction follows a Langmuir‐Hinshelwood mechanism and demonstrates apparent pseudo‐first‐order kinetics, indicating the reaction proceeds via adsorption of both reactants on the catalyst surface followed by surface‐mediated electron transfer.