Enhanced catalytic reduction of 4-nitrophenol using bimetallic MOFs: a one-pot synthesis approach

Several organic pollutants can harm the environment and human health. A typical environmentally toxic contaminant, 4-Nitrophenol (4-NP), may cause serious health issues. Therefore, catalytic reduction (hydrogenation) of 4-nitrophenol into less toxic 4-aminophenol (4-AP) is mostly preferred. A three-dimensional (3D) metal-organic framework of Ni-MOF-74 is mostly used which contains maximum unsaturated metal sites and the catalytic activity is enhanced due to partial exchange at the node position in MOF. In order to study the catalytic hydrogenation/reduction of organic dye, 4-nitrophenol as a model reaction, a bimetallic MOF, FeNi-MOF-74 was prepared by partially substituting Ni with Fe metal. The catalyst was synthesised using a one-pot solvothermal technique, and 4-nitrophenol was then reduced catalytically in aqueous media. For the reduction of nitrophenol, the FeNi-MOF-74 catalyst surpassed Ni-MOF (9.3 x 10-3 s-1) and Fe-MOF (5.4 x 10-3 s-1) with a lower reduction time and a higher rate constant; (1.6 x 10-2 s-1). The high conversion rate and economical induction time are attributed to the bimetallic synergistic effect.