The effect of carbonaceous materials on faradaic and charging current contribution in carbon paste electrodes investigated by chemometrics methods

Different carbon paste electrodes were prepared from carbonaceous materials including multi-walled carbon nanotubes (functionalized and pristine form), graphite powder, pencil graphite, and activated carbon. The electrochemical characteristics and different current contributions of these electrodes were quantitatively compared in K-4[Fe(CN)(6)] and dopamine as two common benchmark redox system, using multivariate curve resolution-alternating least squares (MCR-ALS), as a powerful chemometrics technique. The total current of these electrochemical system recorded in potential-step mode was resolved to its three main current constituents including faradaic current, step charging current, and induced charging current. The contribution of each type of currents in total current was related to the structure and composition of the electrode as well as the nature of the analyte and supporting electrolyte. The focus of this study was on the contribution of faradaic current and nature of conductive phase in carbon paste electrodes. This approach can be effective for the identification of optimal electrode materials for voltammetric analysis and leads to new design criteria for carbon electrodes employed. The obtained results demonstrate that the nature of the conductive phase has a significant effect on faradaic current contribution. Results showed that activated carbon, as conductive phases, has the minimum contribution of faradaic current whereas functionalized multi-walled carbon nanotube has the maximum contribution of faradaic current compared with other carbonaceous materials.