Porphyrinic Carbon Electrocatalysts Decorated with Ultralow Active Metal for Oxygen Reduction Reaction (ORR)

Tuesday, 7 October 2014
Expo Center, 1st Floor, Center and Right Foyers (Moon Palace Resort)
S. M. Hwang, S. Y. Jeon (Korea Institute of Energy Research (KIER)), J. Y. Cheon, S. H. Joo (Ulsan National Institute of Science and Technology (UNIST)), Y. Choi (SABIC Technology Center (STC)), Y. J. Sohn, T. H. Yang, and G. G. Park (Korea Institute of Energy Research (KIER))
The high cost combined with limited performance and low durability of precious metal based-catalysts are major technical barriers to overcome for the commercialization of polymer electrolyte fuel cells (PEFCs). Therefore, exploring the cost effective electrocatalyst with enhanced activity focuses on (1) Pt-M alloy/dealloy with inexpensive transition metals and (2) non-precious metal based electrocatalysts. Unfortunately, the performance of non-precious metal-based materials is still inferior to that of Pt-based catalysts in respect of cell activity and lifespan. Recently, although we found that the self-supported ordered mesoporous porphyrinic carbon (M-OMPC) doped with transition metals, which revealed to have a comparable catalytic activity with Pt/C towards oxygen reduction reaction (ORR), a relatively large amount of catalyst (> 0.6 mg/cm2) is required to be loaded. The catalytic behavior of M-OMPC for ORR is depended on the morphology and mass of the catalyst on the electrode. Thus, a thick membrane electrode with a high catalyst loading is unfavorable for the cell performance in terms of cell resistance and conductivity. In this study we demonstrated an alternative catalyst combined with M-OMPC as a substitution for carbon supports generally used and a trace of Pt particles. The ultralow Pt (<5 wt%) loading on M-OMPC (Pt/M-OMPC) showed a 10-fold enhancement of ORR kinetic activity compared to that of M-OMPC at 0.9 V RHE. The Pt mass activity was also improved by two times compared to that of Pt/C at 0.85 V RHE.