Effect of pre-treatment on the surface and electrochemical properties of screen-printed carbon paste electrodes

摘要

The effect of various electrochemical pre-treatment methods on the surface and electrochemical properties of screen-printed carbon paste electrodes {SPCE) prepared with three different commercial products was examined. It was observed that a positively charged redox couple, e.g., hexaammineruthenium(ru), exhibited quasi-reversible behavior at the untreated SPCE. However, the cyclic voltammograms (CVs) of the SPCE prepared with general-purpose carbon inks did not exhibit clear redox peaks to other representative redox couples [e.g., hexacyanoferrate(ru), hexachloroiridate(Iv), dopamine, and hydroquinone} without activation. Electrochemical pre-treatment methods were sought in four different ~flueous solutions, i.e., sulfuric acid, potassium chloride, sodium hydrogencarbonate, and sodium carbonate, applying various activation potentials. It was found that the pre-treatment procedure in saturated Na_2CO_3 solution at 1.2 V provides a mild and effective condition fo.ractivating the SPCE. By measuring the water contact angles at the SPCE surfaces and recording their SEM images, it was confirmed that the electrochemical pre-treatment effectively removes the organic binders from the surface carbon particles. A prolonged period of activation ( > 5 min) or the use of highpotent.ials ( > 1.2 V)increased the capacitance of the electrode over 20 IA.F cm~(-2). The pre.:treated SPCE behaved like a random array microelectrode, exhibiting a sigmoidal-shapedCV at a slow scan rate. The short pre-anodization method in Na_2CO_3 solution was generally applicable to most SPCE prepared with general-purpose carbon inks.