XAFS analysis of unpyrolyzed CoPPyC oxygen reduction catalysts for Anion-Exchange Membrane Fuel Cells (AMFC)

Asazawa, Koichiro*; Yamamoto, Kazuya*; Yamada, Koji*; Tanaka, Hirohisa*; Matsumura, Daiju   ; Tamura, Kazuhisa   ; Nishihata, Yasuo; Atanassov, P.*

CoPPyC were analyzed with X-ray adsorption fine structure (XAFS) measurements. Acid-treated CoPPyC (CoPPyC-AT) has higher activity than PPyC for oxygen reduction reaction. From the analysis of EXAFS of Co, CoPPyC electrocatalysts as synthesized consist of two peaks. The peak around 1.6 was assigned to Co-N and/or Co-O shells. The second peak around 2.6 was assigned to Co-O-Co shells originated from cobalt hydroxide. CoPPyC-AT showed only one peak of assigned to Co-N and/or Co-O, and it indicates that cobalt hydroxide is removed by acid treatment. It is clear that a coexistence of cobalt and nitrogen in CoPPyC-AT shows specific performance, and pyrolysis is not necessary to make correlation of Co-N.