Capacitor Properties of Activated Carbon Adsorbed Cu(II)-picolinic Acid Complex

Abstract

Activated carbon (AC) has high power dennsity, but has limited specific capacitance. In order to increase its capacitance, Cu(II)-picolinic acid (2-pyridine carboxylic acid) complex was adsorbed on AC by the immersion in an aqueous solution containing copper sulfate and picolinic acid. Electrochemical behavior of activated carbon electrode adsorbed with Cu(II) complex was characterized by cyclic voltammetry and constant current electrolysis in 0.2 mol dm^-3 H₂SO₄. An increase in the cathodic and anodic current was observed at the potential of -0.15 V vs. SCE and the voltammograms were stable at least for 50 cycles. This indicates that the reduction of Cu(II) complex and the oxidation of copper occur stably on the surface of activated carbon. The capacitance of AC increased by the redox reaction of Cu/Cu(II) redox couple and enhancement of approximately 480% in capacitance was obtained with the adsorption of 0.48 mmol g^-1 of Cu(II). This adsorption method is to be expected for increase the capacitance by the addition of pseudo capacitance on activated carbon.