Comparison of two different carbon nanotube-based surfaces with respect to potassium ferricyanide electrochemistry

Abstract

This paper describes the electrochemical investigation of two multi-walled carbon nanotube-based electrodes using potassium ferricyanide as a benchmark redox system. Carbon nanotubes were fabricated by chemical vapor deposition on silicon wafer with camphor and ferrocene as precursors. Vertically-aligned as well as islands of horizontally-randomly-oriented carbon nanotubes were obtained by varying the growth parameters. Cyclic voltammetry was the employed method for this electrochemical study. Vertical nanotubes showed a slightly higher kinetic. Regarding the sensing parameters we found a sensitivity for vertical nanotubes almost equal to the sensitivity obtained with horizontally/randomly oriented nanotubes (71.5 ± 0.3 μA/(mM cm 2 ) and 62.8± 0.3 μA/(mM cm 2 ), respectively). In addition, values of detection limit are of the same order of magnitude. Although tip contribution to electron emission has been shown to be greatly larger than the lateral contribution on single carbon nanotubes per unit area, the new findings reported in this paper demonstrate that the global effects of nanotube surface on potassium ferricyanide electrochemistry are comparable for these two types of nanostructured surfaces.

Do Carbon Nanotubes contribute to Electrochemical Biosensing?

“…And these articles show a minute amount of advancement. For example, the sensitivity varied only from 62.8 ± 0.3 to 71.5 ± 0.3 A/mM × cm 2 in case of differently oriented MWCNT [33], while Cottrell effect results in 9 times larger sensitivity by varying the MWCNT orientation on hydrogen peroxide [63]. It is worth noting that these lastmentioned experiments on ferricyanide have been conducted on MWCNT directly grown on silicon substrates while it is hard to find literature on ferricyanide detection done by using MWCNT dropcasted on SPE.…”

“…Among several different approaches for depositing carbon nanotubes, which also include microspotting [53], electrodeposition [54] and the direct growth [33,55], we simply used the drop casting [44]. While microspotting, electrodeposition and direct growth enable a more precise localization of CNT on the working electrode, it has been shown that drop casting may further extend the electro-active area by creating a sort of conducting CNT forest in the insulating area surrounding the WE [56].…”

“…The direct electron transfer between carbon nanotubes and electrochemically active molecules has been demonstrated as well. Small molecules such as hydrogen peroxide [32], potassium ferricyanide [33], dopamine [34], and etoposide [35] have been detected with electrochemical techniques.…”

Recent Progress on Electrochemical Capacitors Based on Carbon Nanotubes

“…Two of the most common orientations of CNTs are displayed schematically in Figure 3. In general, films of vertically oriented carbon nanotubes exhibit much better electrical and capacitance properties in comparison to films formed from randomly oriented nanotubes [6,50,[54][55][56][57]. Figure 4 shows the structure of the SWCNT layer formed under CVD growth procedure.…”

Development and evaluation of a calibration free exhaustive coulometric detection system for remote sensing.

“…This single electron, perfectly reversible process has been well characterized and extensively used in electrochemical studies [101][102][103]. While many of the salts complexed by cyanide are highly toxic, the ferro-and ferri-cyanide forms have greatly reduced toxicity since the iron form tends to not release free cyanide.…”