Polytyramine (PT) has been electro‐deposited onto multi‐walled carbon nanotube (MWCNT) modified glassy carbon (GC) electrodes via oxidation of tyramine in 0.1 M H3PO4 by cycling the potential over the range of −400 mV to 1300 mV (versus Ag/AgCl). The reactivity of the resulting chemically‐modified electrodes was characterized using cyclic voltammetry in the presence and absence of reduced nicotinamide adenine dinucleotide (NADH). The modified electrodes displayed electrochemical activity due to the formation of quinone species and were catalytically active towards NADH oxidation by lowering the oxidation peak potential by 170 mV compared to the value of the MWCNT modified electrode with a peak potential of 180±10 mV (versus Ag/AgCl). The MWCNT/PT surface was further characterized using SEM and XPS methods, which indicated that a thin polymeric film had been formed on the electrode surface. The present work demonstrates the advantage of using PT as a platform that combines both the immobilization of alcohol dehydrogenase (ADH) and the mediation of NADH oxidation at a low overpotential essential to the design of high performance ethanol biosensors, all within an easily electropolymerizable film. The resulting biosensor displayed an ethanol sensitivity of 4.28±0.06 μA mM−1 cm−2, a linear range between 0.1 mM and 0.5 mM and a detection limit of 10 μM.

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The electropolymerization of tyramine has been investigated using glassy carbon electrodes modified with six classes of carbon materials, namely carbon black, graphitized carbon, graphite, graphene oxide, chemical vapour deposition based multi‐walled carbon nanotubes and arc discharged based multi‐walled carbon nanotubes. These materials were characterized before and after electrodeposition of polytyramine (PT) by Raman spectroscopy, inductively coupled plasma optical emission spectrometry, cyclic voltammetry and amperometry. Previously, other groups have established that impurities present in carbon materials, can play a critical role in electrocatalytic activity. In this study, the presence of graphitic basal plane carbon, rather than metallic impurities, is believed to initiate the formation of a redox active PT film that mediates the oxidation of NADH. The importance of graphitic basal plane carbon was supported by examining the impact of the graphitization of carbon black over the range of 500 to 2000 °C. Graphitic basal plane carbon impurity was demonstrated to be highly active and important with respect to the electrodeposition of a PT film that possesses significant catalytic activity towards the oxidation of NADH.