Green synthesis of Ag/RGO nanocomposite using Punica Granatum peel extract and its catalytic activity for the reduction of 4-nitrophenol

For the past few years, green synthesis of nanoparticles using plant extracts have been widely attracted, because this method provides advantages over physicochemical methods such as simplicity, mild reaction conditions, use of nontoxic solvents such as water, cost effectiveness and elimination of toxic materials [1]. In the recent years, Graphene oxide (GO) and reduced graphene oxide (RGO) are the great interests of many scientists as a new class of promising support and catalysts [2, 3]. GO is a two dimensional material which derived from graphene with a large number of oxygen containing functional groups such as epoxy, carboxyl, carbonyl and hydroxyl groups. The properties of GO include thermal and chemical stability, large specific surface area, high mechanical strength, water dispersity and good electron conductivity [4]. Therefore, GO and RGO could prevent the agglomeration of metal nanoparticles and stabilize them. Nitrophenols and their derivatives are the most stubborn pollutants in industrialwastewaters, so the elimination of them is necessary. Many approaches have been acclaimed to eliminate 4-NP from aquatic environments, including electrochemical treatment, adsorption, and microbialdegradation. These procedures have some major limitations, including limited degradation efficiency, slow degradation rate, highcosts and strict conditions [5]. The catalytic reduction of 4-NP is performed by sodium borohydride in the presence of metal nanoparticles as catalysts which is an environmentally friendly, effective, fast and simple method. Herein, this context outlines the simple, cost effective and environment friendly protocol for the synthesis of Ag/RGO nanocomposite using Punica Granatum peel extract without capping agents or surfactants. The as-synthesized nanocomposite was characterized by UV-Vis, FT-IR, XRD and FE-SEM techniques. The catalytic efficiency of Ag/RGO nanocomposite was tested for the catalytic reduction process of 4-nitrophenol (4-NP) in aqueous solution at room temperature in the presence of sodium borohydride as hydrogen source. The progress of reaction was monitored using UV–Vis spectroscopy and the nanocomposite exhibited a high catalytic activity