Electrocatalytic reduction and sensitive determination of nitrite at nano-copper coated multi-walled carbon nanotubes modified glassy carbon electrode

In this paper, Cu nanoparticles were electrodeposited onto the film of Nafion (Nf)-solubilized multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE), which fabricated a sensitive nano-copper coated multi-walled carbon nanotubes modified glassy carbon electrode (Cunano/CNTs–Nf/GCE) to detect nitrite. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) demonstrated that the Cu nanoparticles coated on MWCNTs were uniform, with an average size of 30 nm. The effects of electrodeposition circles, CNTs–Nf solution concentration and determination conditions such as pH value and applied potential on the current response of Cunano/CNTs–Nf/GCE toward nitrite were optimized to obtain the maximal sensitivity. Moreover, electrochemical experiments revealed that the modified electrode sensor showed high electrocatalytic activity for the reduction of nitrite ion (NO2-). The linear range of the determination of NO2- was from 1.0 × 10−6 M to 6.0 × 10−4 M and the response was fast (less than 5 s). A low detection limit of 8.0 × 10−8 M (S/N = 3) for NO2- was achieved.