Synthesis of highly chemiluminescent graphene oxide/silver nanoparticle nano-composites and their analytical applications

A fast, linker free, one step strategy for in situ preparation of graphene oxide/Ag nanoparticle (GO-AgNP) nano-composites was proposed by reducing AgNO3 with chemiluminescent reagent luminol in the presence of GO. The nano-composites were characterized by transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, UV-Vis absorption spectra, X-ray photoelectron spectroscopy, thermogravimetric analysis, and electrochemical impedance spectroscopy. The results demonstrated that many Ag nanoparticles (AgNPs) with an average diameter of about 22 nm were uniformly dispersed on the surface of GO nanosheets. Luminol molecules were also decorated on the surface of the nano-composites. Thus the nano-composites showed excellent chemiluminescence (CL) activity when reacting with H2O2. Furthermore, the formation mechanism of the as-prepared GO-AgNP nano-composites is proposed as follows: Ag+ adsorbs on the surface of GO via an electrostatic force and Ag+-pi orbital interaction. Afterwards, they are in situ gradually reduced by luminol molecules to AgNPs on the surface of GO and some luminol molecules are attached on the surface of the nano-composites. Finally, it was found that glutathione could enhance the CL intensity between GO-AgNP nano-composites and hydrogen peroxide. On this basis, a sensitive and selective method for the detection of glutathione was developed. This method showed a detection limit of 25 mu mol L-1 and a linear range from 30 to 1000 mu mol L-1. The nano-composites may be attractive and advanced composite materials with great promise as advanced building blocks, CL labels, and platforms for various analytical devices with CL detection such as sensors, microchips and bioassays.