A rotating disk electrode study on catalytic activity of iron(II) phthalocyanine-modified electrodes for oxygen reduction in acidic media

Abstract

Catalytic activity of monometric metal macrocycles for oxygen reduction reaction (ORR) was investigated using rotating disk electrode voltammetry in acidic media. Iron(II) phthalocyanines (FePc) and cobalt(II) tetraphenylporphyrins (CoTPP) were immobilized on Au surfaces through molecular wires with different terminal groups of pyridine and isocyanide. The measured ORR behavior of FePc was largely influenced by the axial ligand while CoTPP promoted only the two-electron reaction regardless of the axial ligand. The FePc immobilized with pyridine was easily detached from the surface under the ORR condition, and was able to promote the four-electron reaction only under the high overpotential application. The FePc with isocyanide was more stable with the activity for the four-electron reaction, due to stronger electron donation to Fe central ions.