ZnO@graphene nanocomposite modified electrode for sensitive and simultaneous detection of Cd (II) and Pb (II)

Zinc Oxide (ZnO) nanorods were synthesized by using zinc acetate as a precursor via thermal decomposition method and then used to prepare ZnO@G nanocomposite by facile room-temperature approach using a colloidal coagulation effect. The as prepared ZnO@G nanocomposite was applied to modify the working electrode surface in an electrochemical sensor of Cd2+ and Pb2+ for the first time. The morphologies of ZnO and ZnO@G nano composite were characterized by transmission electron microscopy, that exhibits the nanorod shape with an average diameter of 89 +/- 18 nm, uniformly dispersed and intercalated between each G layer. Furthermore, the important factors affecting on the sensor sensitivity, including ZnO@G ratio, ZnO@G concentration, Bi3+ concentration and electrochemical parameters were systematically investigated using square-wave anodic stripping voltarnmetry. Under the optimal conditions, a linear range was found to be 10-200 mu g L-1 and the detection limits were 0.6 and 0.8 mu g L-1 for Cd2+ and Pb2+, respectively. Eventually, it was successfully used for the simultaneous detection of Cd2+ and Pb2+ in real wastewater samples and the results corresponded well with a standard inductively coupled plasma-optical emission spectroscopy.