Green Synthesis Of Graphene-gold Nanocomposite As Electrochemical Sensor For Chromium ? Detection

Nano-materials have been widely used for in situ environmental remediation due to its special property. At presently, chemical synthesis is a key role in the development of nanotechnology. However, limitations in the chemical method including low production rates, high energy consumption, and high cost, as well as toxicity used solvents result in unable to large-scale in situ remediation. The green synthesis of nano-materials using plant extracts mainly applied to the degradation and adsorption. The application to electrochemical detection using green synthetic nano-materials has been rarely reported. Hence, a novel green synthetic nano-materials with electrochemical detection technology was proposed for sensitive and selective detection of chromium VI.Firstly, green tea extract can be used as the "green" reducing agent for preparing nano-materials via investigation of the optimum green synthesis condition. The ability of polyphenols and caffeine in green tea extract to function not only as natural reducing agents, but also as protective agent. Therefore, iron nanoparticles (Fe-NPs) using green tea extract have been successful synthesis, and studying the effect of various atmospheres on composition and reactivity of Fe NPs. The results indicated that Fe NPs has a better adsorption and reducing activity instead of poor electrical conductivity.Secondly, Au nanoparticles were selected as the research object due to its strong electrical conductivity. Au nanoparticles was synthesized using green tea extract and then modified on glassy carbon electrode (GCE) via self-assembled technology to prepare a novel "green" electrochemical sensor. Electrochemical characterization analysis demonstrated that the nano-Au/GCE was sensitive and selective for the detection of chromium VI.Finally, RGO was used as a carrier to load various nano-metallic materials owing to its biocompatibility and electrical conductivity. Au nanoparticles/reduced graphene oxide composite (nano-Au/RGO) were successfully synthesized using "green" method. Then nano-Au/RGO was modified on the surface of GCE to prepare a new functional electrochemical sensor to enhanced the electron transformation. The characterization and electrochemical performance tested to further investigate the nano-Au/RGO/GCE sensor used to determinate chromium VI. This synthetic process conformed to the "green" synthesis route to provide a new insight of green preparation of electrochemical sensor.