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

摘要

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.