Green Synthesis of Gold Nanoparticles for Fabrication of an ElectrochemicalSensor Sensitive to Nitrophenial based on Graphene Nanoplatelets/GoldNanoparticles

Synthesis of chemical compounds using environmentally friendly materials is the goal of greenchemistry. In recent years use of planets as stable and available sources to prepare metalnanoparticles has more attention for researchers. Synthesized nanoparticles using the aim ofgreen reagents can be used in the bio application such as fabrication of electrochemical sensors[1]. In this regard, gold nanoparticles (AuNPs) due to unique properties such as highconductivity, high surface area and electro catalytic properties recently used in the fabrication ofoptic and electrochemical sensors [2]. Analysis of nitrophenols in natural water resources is animportant indicator to quality control of water. 4-Nitrophenol (4-NP) is one of the hazardouschemicals in contaminate list of environmental protection agenay (EPA) duo to its stability andpoisonous. Respiration or eating of 4-NP in the short period causes hard headache and drowsy,nausea and dark blue skin. In addition 4-NP was reported as cancerous tratogen and tagen so itsapplication should be under control [3]. So, monitoring of 4-NP in water resources using asensitive and selective electrochemical sensor is highly interested. In this work, a novel method ispresented for green synthesis of AuNPs using extracted E. tereticornis leaves as the reducingagent in the presence of HAuCl4 in ambient temperature. The synthesized AuNPs was mixedwith graphene nanoplatelets (GNPs) under sonication to form a homogeneous nanocomposite(AuNPs/GNPs). Characterization of the nanocomposite using UV-Visible spectroscopy, Fouriertransform infrared spectroscopy (FTIR), and field emission scanning electron microscopycoupled with energy dispersive spectroscopy (FESEM-EDS) showed a homogeneous distributionof AuNPs nanoparticles on GNPs sheets. Due to synergetic effect of good electrocatalyticconductivity of GNPs, the synthesized nanocomposite was drop casted on the surface of glassycarbon electrode and used as an electrochemical sensor (AuNPs/GNPs/GCE) for determination of4-NP using differential pulse anodic stripping voltammetry. Under optimal conditions ofphosphate buffer (0.01 M, pH 4.0), scan rate of 0.05 V/s, drop castingnanocomposite ratio (AuNPs/GNPs) of 5 (V/V), differential pulse voltammetry of 4-NP showedan oxidation peak at around 0.025 V due to exchange of 2 electrons and protons. The fabricatedsensor has good potential for determination of 4-NP in lake water, reverse osmosis drink waterand natural mineral water with satisfactory results.properties as well as conductive nature of AuNPs microspheres and large surface area with high

Keywords:

Gold nanoparticles , Graphene nanoplatelets , 4-Nitrophenol , Electrochemical sensors , Water