Ultra-Low Pt Decorated Porphyrinic Carbon Based Hybrid Electrocatalysts for Oxygen Reduction Reaction

Abstract

As the fuel cell market has been growing, the price competitiveness of polymer electrolyte fuel cell (PEFC) became the most important factor for its commercialization. In particular, the production of membrane-electrode assembly (MEA) consisting of Pt-based electrocatalyst is a critical hurdle for the cost reduction of PEFCs. Therefore, many researchers have veen focusing on the development of cost effective electrocatalysts such as non-precious metal based catalysts (NPMCs) or low content platinum based catalysts to minimize Pt loading by morphological and structural tunings with inexpensive transition metals. Recently, we reported the M-N doped ordered mesoporous porphyrinic carbon (M-OMPC, M=Fe, Co) which showed a comparable ORR activity to that of Pt/C in an acid medium. However, an inferior MEA performance of M-OMPC is a practical barrier because of high mass transport resistance and electrical resistance, which mainly comes from the thicker electrode of M-OMPC. In this study, we proposed a new approach for enhanced ORR activity as well as reduction of noble metal loading content via adding a trace of platinum nanoclusters on M-OMPC. The Pt/M-OMPC (Pt~5 wt%) hybrid catalyst showed an increased Pt based mass activity and specific activity by a factor of 7, compared to that of Pt/C (5 wt%) at 0.85 V RHE.