Nitrogen-doped multi-walled carbon nanotubes modified with platinum, palladium, rhodium and silver nanoparticles in electrochemical sensing

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) were fabricated by means of chemical vapour deposition technique and decorated with platinum (PtNPs), palladium (PdNPs), rhodium (RhNPs) and silver (AgNPs) nanoparticles possessing diameter 2.7, 2.6, 2.7 and 3.4 nm, respectively. The electrochemical responses of composite films, further denoted as N-MWCNTs/MNPs (M: Pt, Pd, Rh and Ag) towards ferrocyanide/ferricyanide, [Fe(CN)₆]^3−/4− were investigated in large concentration range (0.099–0.990 mM) in potassium chloride solution (1.0 M). The findings demonstrate that the electrochemical response and sensitivity of N-MWCNTs are improved significantly upon modification with metal nanoparticles. A strong dependence of film’s electrochemical fineness on type of metal nanoparticles used for modification can be observed. Namely, the current response, the charge-transfer kinetics, and the detection capability of novel composite films enhance with the following order: N-MWCNTs < N-MWCNTs/RhNPs < N-MWCNTs/PdNPs < N-MWCNTs/PtNPs < N-MWCNTs/AgNPs. The findings demonstrate that the novel N-MWCNTs/MNPs composite films can be considered as powerful and useful materials for electrochemical sensing.