Single walled carbon nanotubes decorated vanadyl phthalocyanine composite for electrochemical oxygen reduction in fuel cells

Abstract

Vanadyl phthalocyanine (VOPc) has been immobilized on single walled carbon nanotubes by the adsorption process and characterized using UV-vis spectroscopy, infrared spectroscopy and X-ray diffraction techniques. Electrochemical characterization of VOPc immobilized SWCNTs (SWCNTs-VOPc) has been done by coating an aqueous colloid of SWCNTs-VOPc on glassy carbon electrode (represented as GC/SWCNTs-VOPc). GC/SWCNTs-VOPc exhibits a pair of peaks at –265 and –97 mV (at 20 mV s^-1 in 0.1 <i>M</i> H₂SO₄) due to the characteristic redox process, V^IV/III of VOPc. Further, electrocatalytic reduction of oxygen is analysed using GC/SWCNTs-VOPc electrode by cyclic voltammetry. GC/SWCNTs-VOPc electrode efficiently reduces oxygen in 0.1 <i>M</i> H₂SO₄ with a low onset potential of 0.16 V. Also, GC/SWCNTs-VOPc exhibits significant storage stability, retaining 91% of its original catalytic reduction current after 10 days storage at room temperature in air and dry conditions.