Electrocatalytic reduction of dioxygen at a modified glassy carbon electrode based on Nafion ®-dispersed single-walled carbon nanotubes and cobalt–porphyrin with palladium nanoparticles in acidic media

Abstract

Cathodic dioxygen (O 2) reduction was performed at a modified glassy carbon electrode (GCE) by single-walled carbon nanotubes (SWCNT)/Nafion ® (NF) film with cobalt (II) tetra (2-amino-phenyl) porphyrin (CoTAPP) and palladium (Pd) nanoparticles incorporated and employed as doping agents. Both the electrochemical behavior of SWCNT with a P(CoTAPP)–Pd nanoparticle matrix and the electrocatalytic reduction of O 2 were investigated using transmission electron microscopy (TEM), cyclic voltammetry (CV) and rotating ring-disk electrode (RRDE) techniques in 0.1 mol l −1 H 2SO 4 aqueous solutions. The electrocatalytic reduction of O 2 at the SWCNT/NF/P(CoTAPP)–Pd composite film established a pathway of four-electron transfer reductions into H 2O. Hydrodynamic voltammetry revealed that the modified electrode was catalyzed effectively by the four-electron transferred reduction of dioxygen into H 2O with minimal generation of H 2O 2. The SWCNT/NF/P(CoTAPP)–Pd composite film showed a highly efficient electrocatalytic performance. P(CoTAPP)–Pd was an effective mediator for the reduction of dioxygen and was responsible for the enhanced catalytic activity.