The voltammetric applications and frequency-dependent properties of screen-printed electrodes and carbon nanomaterial electrodes

Randviir, Edward P ORCID: https://orcid.org/0000-0001-7252-8494 (2014) The voltammetric applications and frequency-dependent properties of screen-printed electrodes and carbon nanomaterial electrodes. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

This thesis reports the voltammetric applications and fundamental frequency-dependent properties of carbon-based electrode materials. A range of electrochemical systems hasve been investigated, and new materials have been electrochemically characterised, which will be of use to the field of electrochemistry. In Chapter 3 of this thesis, different graphenes were utilised as electrode composite materials, and their electrochemical behaviour was de-convoluted. It was found that surfactant-free graphenes were useful for the detection of guanine in terms of a reduced activation potential, which is thought to be derived from a pi-pi adsorption mechanism. The oxygen reduction reaction was also focussed upon and it was found that the type of graphene utilised did not affect the electrochemical mechanism in the respective reactions, but the peroxide yields changed. This could have dramatic ramifications for users choosing carbon materials as catalyst supports. Screen-printed electrodes were applied to novel systems including theophylline and creatinine, finding that their use as portable sensors was viable in two ways. For theophylline, a direct oxidation mechanism was useful for the detection of the medicine, while in the case of creatinine, an indirect detection method was found to be effective as creatinine is not electrochemically active. In Chapter 5, the first graphene screen-printed electrodes were developed and characterised. The result was two graphene screen-printed electrodes, with differing electrochemical properties, both of which could be used for different applications. Finally, Chapter 6 focusses upon whether electrochemical impedance spectroscopy is useful for screen-printed electrodes and carbon modifications. The work in this thesis finds that a synergy could potentially be formed, and in particularly, has found that it would be wise to operate screen-printed electrodes around +0.2 V due to this being the point where there is no net charge at the electrode surface under standard conditions.