Tea polyphenols mediated Zero-valent Iron/Reduced graphene oxide nanocomposites for electrochemical determination of Hg2+

Herein, we have developed a chemically modified glassy carbon electrode (GCE) using tea polyphenols mediated zero-valent iron/reduced graphene oxide nanocomposites (rGO-ZVI-P) for rapid determination of Hg2+ in water. Highly conductive rGO-ZVI-P were fabricated by a green chemical method using tea polyphenols as the reductant. The rGO-ZVI-P shows a unique affinity to aqueous Hg2+ due to a synergy between ZVI and rGO. The rGO-ZVI-P electrochemical sensor shows optimal performance for Hg2+ determination in pH 5.00 phosphate buffer and 180 s accumulation time at -1.2 V accumulation potential used under square wave anode stripping voltammetry (SWASV). At these conditions, the Hg2+ determination sensitivity is 41.42 mu A/mu M and the determination limit is 1.2 nM. There are no interferences to the rGO-ZVI-P modified GCE sensor in the presence of 0.5 mu M Cd2+ , 0.5 mu M Pb2+ , and 0.5 mu M Cu2+ in solution, either in discrete cations or multi-cations modes. Moreover, the typical chemical species found in the matrix of river water samples do not interfere with the as-fabricated Hg2+ electrochemical sensor. The Hg2+ determination by the rGO-ZVI-P modified GCE sensor is repeatable, stable, and robust, and it has potential in environmental applications.