Electrochemical Responses and Sensitivities of Films Based on Multi-Walled Carbon Nanotubes in Aqueous Solutions

摘要

Novel films consisting of multi-walled carbon nanotubes (MWCNTs) were fabricated by means of chemical vapor deposition with decomposition of either acetonitrile (ACN) or benzene (BZ) using ferrocene as catalyst. The electrochemical responses of MWCNT-based films towards the ferrocyanide/ferricyanide, [Fe(CN)_6]~(3-/4-) redox couple were probed bymeans of cyclic voltammetry and electrochemical impedance spectroscopy at 25.0 ± 0.5 ℃. Both MWCNT-based films exhibit Nernstian response towards [Fe(CN)_6]~(3-/4-) with some slight kinetic differences. Namely, heterogeneous electron transfer rate constants lying in ranges of 2.69×10~(-2)–1.7×10~(-3) and 9.0×10~(-3)–2.6×10~(-3) cm·s~(-1) were obtained at ν = 0.05 V·s~(-1) forMWCNT_(ACN) andMWCNT_(BZ), respectively. The detection limit of MWCNT_(ACN), estimated to be about 4.70×10~(-7) mol·L~(-1) at ν = 0.05 V·s~(-1), tends to become slightly poorer with the increase of the scan rate, namely at ν = 0.10 V·s~(-1) the detection limit of 1.70×10~(-6) mol·L~(-1) was determined. Slightly poorer response abilitywas exhibited byMWCNTBZ; specifically the detection limits of 1.57×10~(-6) and 4.35×10~(-6) mol·L~(-1) were determined at ν = 0.05 and ν = 0.10 V·s~(-1), respectively.The sensitivities of MWCNT_(ACN) and MWCNT_(BZ) towards [Fe(CN)_6]~(3-/4-) were determined as 1.60×10~(-7) and 1.51×10~(-7) A·L·mol~(-1)·cm~(-2), respectively. The excellent electrochemical performance of MWCNT_(ACN) is attributed to the presence of incorporated nitrogen in the nanotube’s structure.