Anion-Exchange Membrane Fuel Cells: Dual-Site Mechanism of Oxygen Reduction Reaction in Alkaline Media on Cobalt-Polypyrrole Electrocatalysts

作者：Olson Tim S; Pylypenko Svitlana; Atanassov Plamen^*; Asazawa Koichiro; Yamada Koji; Tanaka Hirohisa

来源：Journal of Physical Chemistry C, 2010, 114(11): 5049-5059.

DOI：10.1021/jp910572g

The oxygen reduction reaction (ORR) processes in alkaline media that occur on a family of electrocatalyst materials derived from a Co containing precursor and polypyrrole/C composite material (PPy/C) are investigated here. The effects of Co loading and heat treatment temperature on the CoPPy/C materials are revealed through Structural evaluations and electrochemical Studies. Principle component analysis (PCA), a multivariant analysis (MVA) technique, is used to establish structure-to-property correlations for the CoPPy/C materials. In all cases, pyrolysis leads to formation of a composite catalyst material, featuring Co nanoparticles coated with Co oxides and Co(2+) species associated with N-C moieties that originate from the polypyrrole Structures. Based on these correlations, we are able to propose all ORR mechanism that Occurs on this Class of non-platinum based fuel cell cathode catalysts. The correlations suggest the presence of a dual site functionality where O(2) is initially reduced at a Co(2)(+) containing N-C type site in a 2 e(-) process to form HO(2)(-), an intermediate reaction product. Intermediate species (HO(2)(-)) call react further in the series type ORR mechanism at the decorating CoxOy/Co surface nanoparticle phase. The HO(2)(-) species can undergo either further electrochemical reduction to form OH species or chemical disprotonation to form OH(-) species and molecular O(2).

• 出版日期2010-3-25