-Extended nonplanar cobalt porphyrins immobilized on MWCNTs as efficient electrocatalysts for selective oxygen reduction reaction

Two pi-extended cobalt porphyrins are synthesized and one of them is crystallographically characterized. The nanocomposites of nonplanar (curved) porphyrin immobilized multi-walled carbon nanotubes were thoroughly characterized spectroscopically and microscopically, showing similar to 200 mV positive shift in the O2 reduction peak potential in aqueous media and similar to 100 mV shift in the onset potential of the O2 reduction relative to the control meso-tetraphenylporphyrinatocobalt(ii) nanocomposite. Both the pi-extended cobalt porphyrin immobilized nanocomposites efficiently catalyze selective 4e-/4H+ O2 reduction under ambient conditions with excellent methanol tolerance and high stability due to effective pi-pi interactions, and could be an alternative for expensive Pt-based cathode materials in fuel cells. Two pi-extended nonplanar cobalt porphyrins embedded MWCNTs manifested efficient electrocatalysts for selective ORR under ambient conditions with excellent methanol tolerance and high stability due to effective pi-pi interactions.