Cobalt nanoparticles as reusable catalysts for reduction of 4-nitrophenol under mild conditions

Facile reduction of p-nitrophenol to p-aminophenol by sodium borohydride catalysed by cobalt nanoparticles (CoNPs) has been discussed. A simple approach has been made to synthesize highly active and ordered structures of CoNPs. The air-stable nanoparticles were prepared from cobalt sulphate using tetrabutyl ammonium bromide as surfactant and sodium borohydride as reductant. The cobalt nanocolloids in aqueous medium were found to be efficient reusable catalysts for the p-nitrophenol reduction. Palladium nanoparticles prepared from palladium chloride and the same surfactant were found to reduce p-nitrophenol but lose their catalytic efficiency after recovery. Based on chemical and kinetic studies, an attempt has been made to elucidate the mechanism of p-nitrophenol reduction using these nanoclusters.