Enhancing the electrocatalytic activity of Fe phthalocyanines for the oxygen reduction reaction by the presence of axial ligands: Pyridine-functionalized single-walled carbon nanotubes

We have examined the electrocatalytic activity of iron phthalocyanine (FePc) and perchlorinated 16(Cl)FePc for oxygen reduction reaction (ORR) in alkaline medium with two molecules either adsorbed on external surface single-wall carbon nanotubes (SWCNT) or covalently anchored via an axial pyridine ligand pyridine-functionalized (py-SWCNT). Regardless particular type, ORR is higher when substrate py-SWCNT rather than SWCNT. The Tafel slopes are very similar Fe macrocyclic complexes attached to SWCNTs different configurations, suggesting a common rate-determining step all four catalysts. It also observed that, both SWCNT supports, FePc. This attributed electron-withdrawing effect peripheral non-peripheral chlorine atoms ligand. While FeN4 macrocycles known be located strong binding side volcano correlation including several MN4 species, substituents decrease energy O2 central cation, thereby moving up macrocycle catalyst towards apex correlation. Both effects were optimized py-SWCNT, which more active FePc py-SWCNT. Here we show that electron withdrawing groups (-Cl) combined collaborative increasing catalytic Fe-phthalocyanines confined walls nanotubes.