Bio-inspired immobilization of silver and gold on magnetic graphene oxide for rapid catalysis and recyclability

[Display omitted] •A bio-inspired strategy is followed to fabricate two catalysts containing Au and Ag.•Magnetic graphene oxide is used as supporting material for the noble metals.•Both nanocatalysts exhibit high catalytic reduction efficiency.•A comparison of Au and Ag nanoparticles as catalysts is investigated. Noble metal nanoparticles have been widely employed for catalysis owing to their remarkable ability to reduce the activation energy of certain reactions. In this work, we followed a bio-inspired strategy to fabricate two magnetic nanocatalysts comprised of gold (AuNPs) and silver (AgNPs) nanoparticles. Magnetic graphene oxide (MGO), synthesized by deposition of Fe3O4 nanoparticles on graphene oxide (GO), was used as the support material. Inspired by the adhesive property of marine mussel, polydopamine (PDA) was used as the organic linker for robust immobilization of AuNPs and AgNPs on MGO surface to produce MGO-PDA@Au and MGO-PDA@Ag, respectively. We employed a wide range of microscopic and spectroscopic techniques such as HRTEM, FESEM, EDS, XPS, XRD, FTIR etc. to characterize the catalytic nanomaterials. The catalytic performances of these as-fabricated catalysts were investigated by monitoring the reductions of methylene blue (MB) and 4-nitrophenol (4-NP) by NaBH4 as model reactions. Thermogravimetric analysis and magnetization tests were also done to study the thermal stability and magnetic properties of the nanocomposites. The reaction rate constants obtained for both nanocomposites were found to be higher than most of the similar investigations reported elsewhere. In addition, we proposed a comparison of the catalytic performances of gold and silver nanoparticles when immobilized on same supporting material. This comparison provides means to have better insights of the factors affecting the catalytic performances of AuNPs and AgNPs along with identifying their selectivity towards specific catalytic applications.