Electrochemical modification of ITO with Di-(3-diaminorpropyl)-viologen and its electrocatalytic behavior of the oxygen reduction reaction in an alkaline solution

We present a Di-(3-diaminopropyl)-viologen cation radical (DAPV+) modified ITO electrode prepared by an electrochemical reduction of DAPV2 + in an aqueous solution and its electrocatalytic behavior for the oxygen reduction reaction (ORR). Electrochemically reduced DAPV+ was self-assembled on an ITO surface, and cyclic voltammograms (CVs) show an EC-typed voltammetric shape induced by the electrochemical reduction of DAPV2 +. A surface coverage of adsorbed DAPV+ (DAPV+ads) on an ITO surface, which was formed by scanning a potential from 0.20 to − 0.55 V for 1000 cycles (DAPV1000-ITO) was estimated to 5.1 × 10− 10 mol/cm2, and DAPV+ads on an ITO surface was spectroscopically and topographically identified. DAPV+ads on an ITO surface did not show any blocking effect on 1e− transfer in an outer sphere, Fc/Fc+ redox reaction. However, an electrochemical activity for the ORR in a 0.1 M KOH solution was enhanced in order of a DAPV100-ITO, DAPV500-ITO, and DAPV1000-ITO electrode. An electron number in the ORR obtained from a DAPV1000-ITO electrode was estimated to 2, indicating that a DAPV+ modified ITO electrode electrochemically mediates 2e− transfer pathway for the ORR in the alkaline aqueous solution.

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