Ethylene diamine mediated cobalt nanoparticle studded graphene oxide quantum dots with tunable photoluminescence properties†
Abstract
Preparation of graphene oxide quantum dot-inorganic nanoparticle hybrids is still an unexplored area of graphene-centred research. The present study demonstrates the ethylene diamine mediated in situ synthesis of cobalt oxide nanoparticles (Co3O4 NPs) studded on graphene oxide quantum dots (GOQDs). Ethylene diamine(en) is known to form a stable coordination complex with Co2+. CoCl2 was used as a precursor material for Co-nanoparticle formation as small sized Co2+ ions can enter the interlayer spacing between the graphene sheets. Ethylene diamine gets attached to the GOQDs via ring opening of epoxy groups on the GOQDs and pulls the Co2+ ions from the medium onto the GOQDs. On treating this system with hydrogen peroxide, GOQDs-en-Co3O4 nanoparticle composites with enhanced optical properties could be successfully prepared. We also tried to explore the potential of our system as a reversible on/off fluorescence switching material based on oxidation–reduction chemistry and could find satisfactory results. Such systems we believe can prove to be model systems for quantum level graphene-inorganic nanoparticle hybrid nanocomposites with potential for application in optoelectronic devices.