▎ 摘　　要

Several nanomaterials and techniques for the detection of mercuric ions (Hg2+)have been developed in the past decade. However, simple, low-cost and rapid sensor for the detection of heavy metal ions yet remains an important task. Herein, we present a highly sensitive electrochemical sensor for the femtomolar detection of Hg2+ based on polypyrrole, pectin, and graphene (PPy/Pct/GR) which was prepared by one step electrochemical potentiodyanamic method. The effect of concentration of pectin, polypyrrole and graphene were studied for the detection of Hg2+. The influence of experimental parameters including effect of pH, accumulation time and accumulation potential were also studied. Different pulse anodic stripping voltammetry was chosen to detect Hg2+ at PPy/Pct/GR/GCE modified electrode. The fabricated sensor achieved an excellent performance towards Hg2+ detection such as higher sensitivity of 28.64 mu A mu M-1 and very low detection limit (LOD) of 4 fM at the signal to noise ratio of 3. The LOD of our sensor offered nearly 6 orders of magnitude lower than that of recommended concentration of Hg2+ in drinking water by United States Environmental Protection Agency and World Health Organization. Compared to all previously reported electrochemical sensors towards Hg2+ detection, our newly fabricated sensor attained a very LOD in the detection of Hg2+. The practicality of our proposed sensor for the detection of Hg2+ was successfully demonstrated in untreated tap water. (C) 2016 Elsevier Inc. All rights reserved.