Green synthesis of gold nanoparticles using gum polysaccharide of Cochlospermum religiosum (katira gum) and study of catalytic activity

A green synthesis of gold nanoparticles (Au NPs) using aqueous solution of a hetero-polysaccharide, extracted from the gum of Cochlospermum religiosum (katira gum), has been demonstrated in this work. The hetero-polysaccharide plays the role of both reducing and stabilizing agent. The synthesized Au NPs were characterized by UV–vis spectroscopy, HR-TEM, XRD and FT-IR experiments. The surface plasmon resonance (SPR) band of UV–vis spectrum around 528 nm confirmed the formation of Au NPs. Transmission electron microscopic analysis showed an average size of Au NPs of 6.9 nm. The fcc crystalline nature of these particles was identified by XRD analysis and SAED pattern. These Au NPs also function as an efficient heterogeneous catalyst in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The reduction of 4-NP follows pseudo-first-order kinetics with rate constant 2.67×10−2 min−1.