Core-shell Au@Ag nanoparticles on carboxylated graphene for simultaneous electrochemical sensing of iodide and nitrite

Herein, a novel electrochemical sensor based on core-shell Au@Ag nanoparticles deposited on carboxylated graphene (CG) was constructed for the simultaneous electrochemical determination of nitrite (NO2-) and iodide (I-). The CG/Au@Ag nanocomposite was prepared via two-step simple chemical reduction method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the CG/Au@Ag nanocomposite. Au@Ag nanoparticles were distributed on the CG surface, providing more active sites for the electrocatalytic active center. The strong synergistic effect between Au@Ag nanoparticles and CG improved the conductivity of nanoparticles and provided a significant electrocatalytic performance on the flexible sensor. The CG/Au@Ag modified electrode showed a wide linear concentration range of 2.5-1250 mu M, a low detection limit of 0.15 mu M for NO2- and corresponding linear ranges of 3.5-1000 mu M (peak I) and 500-1000 mu M (peak II), and the detection limit of 0.1 mu M for I- . It also demonstrated good anti-interference ability against various common interfering substances. Finally, the sensing platform was successfully applied to simultaneous determination of NO2- and I in real samples. The present electrochemical strategy is promising to broaden the practical electrochemical application in environment.