Nafion stabilized silver nanoparticles modified electrode and its application to Cr(VI) detection

A silver nanoparticles/Nafion film composite material modified glassy carbon electrode (GCE) was prepared and used as a kind of superior electrochemical sensor for Chromium(VI). Nafion (Nf), a cation-exchange polymer, was employed as the conductive matrix in which Ag nanoparticles (Agnano) can be tightly attached to the electrode surface. Agnano were obtained by direct electrodeposition and showed excellent catalytic ability toward Cr(VI) reduction. Such a designed GCE/Nf/Agnano shows outstanding sensitivity and selectivity to Cr(VI) reduction. A linear relationship between the reduction current and Cr(VI) concentration was obtained covering the concentration range from 2 to 230 ppb with excellent sensitivity (1.1 nA/ppb) and low detection limit (0.67 ppb). The electrochemically formed Agnano were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques. Interference from other heavy metal ions such as Cr3+, Cd2+, Cu2+, and Hg2+ associated with Cr(VI) analysis could be effectively diminished. The practical application of the proposed sensor was carried out for determination of trace level of Cr(VI) in real water sample. The present electrode is reliable, stable, sensitive and low-cost.