Electrocatalytic Activity of Nitrogen-Doped Carbon Nanotubes Decorated with Gold Nanoparticles

Films consisting of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) were fabricated by means of chemical vapor deposition technique and decorated with gold nanoparticles (AuNPs) of different diameters (5, 14, and 35 nm). The electrochemical responses of AuNPs-modified N-MWCNTs films, further denoted as N-MWCNTs/AuNPs, were investigated towards ferrocyanide/ferricyanide, [Fe(CN)(6)](3-/4-) redox system in aqueous potassium chloride solutions. The findings reveal strong dependence of film's electrochemical response on diameter of AuNPs. Namely, the electrochemical response expressed in terms of peak current density enhances and the kinetic of electron transfer tends to be faster with the increase of diameter of AuNPs. Furthermore, an obvious improvement of film's detecting capability towards [Fe(CN)(6)](3-/4-) occurs with the increase of diameter of AuNPs. The findings demonstrate that by varying the size of AuNPs attached onto N-MWCNTs/AuNPs, the film's electrochemical response and detection capability can be tuned.