Carbon nanotube electrodes for electroanalysis

• Main Author: Toh, Siong Keong.
• Other Authors: Liu Erjia
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electric apparatus and materials
• Online Access: http://hdl.handle.net/10356/40075
• Institution: Nanyang Technological University

Carbon nanotubes (CNTs) have numerous potential applications due to its unique properties. Given its good electrochemical properties, one of the potential applications is as an electrode for electroanalysis, thus providing a possible alternative to platinum and gold electrodes. CNTs are assembled in polyvinyl alcohol (PVA) to form a homogenous solution. 6µL of this homogenous solution will be coated onto glassy carbon electrodes, which will then be tested for CNTs’ suitability as an electrode. Five parameters (concentration of CNTs, concentration of PVA, pH values and concentration of surfactants such as SDS and HDTAB) are studied for the best possible electroanalysis performance of CNTs. The best combination of parameters is 2.5mg/mL of PVA and 10mg/mL of CNT with no surfactants added at a pH value of 7. The addition of surfactants will result in a better dispersion of CNTs in PVA but on the other hand, it affects the electroanalysis performance of CNTs. Characterisation of CNTs is done by scanning electron microscopy, Raman spectroscopy and potentiostat/galvanostat station to investigate the structural and electrochemical properties of CNTs. From Raman spectrum, it is understood that the CNTs used is of semiconducting nature due to the presence of two peaks at the G-band. From scanning electron microscopy images, it is observed that the dispersion of CNTs is better in HDTAB than in SDS but from the electroanalysis results it shows that the addition of surfactants will result in poor electroanalysis performance of CNTs. Electroanalysis performance of CNTs is measured by the magnitude of the oxidation and reduction peak current responses, the peak-to-peak separation between the cathodic and anodic peaks, and the ratio of cathodic peak to anodic peak. CNTs-PVA modified glassy carbon electrode has shown higher oxidation and reduction current peak responses and shorter peak-to-peak separation as compared to bare glassy carbon electrode. This is due to the presence of a large electro-active surface area and fast electron kinetics of CNTs. The challenges faced in this project are uniformity in length and diameter of CNTs, alignment of CNTs in the same orientation and striking a balance between dispersion and electroanalysis performance of CNTs. Since the addition of surfactants will affect the electroanalysis performance of CNTs, future experiments can focus on growing longer CNTs to at least a few mm or cm and also aligning CNTs vertically to achieve possible better results.