Development of Highly Active and Durable Hybrid Cathode Catalysts for Polymer Electrolyte Membrane Fuel Cells

Carbon composite catalyst (CCC) and activated carbon composite catalyst (A-CCC), both containing active catalytic sites for oxygen reduction reaction (ORR), were synthesized and used as supports to develop hybrid cathode catalysts (HCCs). HCCs are a combination of CCC or A-CCC supports and Pt or Co-doped Pt catalysts. Uniform Pt deposition on these supports was accomplished through surface modification and modified polyol processes. The Co-doped Pt was synthesized at 800°C in the presence of polyaniline protective coating. The HCCs, namely Pt/A-CCC, Co-doped Pt/CCC, and L-Co-doped Pt/CCC catalysts showed peak power densities of 944, 857, and 1050 mW cm −2 , respectively, which are much higher than the commercial Pt/C (746 mW cm −2 ). Furthermore, the Pt/C showed very high power density loss (63%) when compared to HCCs (16–26% loss) after 30,000 potential cycles (0.6–1.0 V). The Pt/A-CCC catalyst showed excellent support stability when subjected to potential holding at 1.2 V for 400 h (27 mV loss at 800 mA cm −2 ) and 5,000 potential cycles between 1.0 and 1.5 V (25 mV loss at 1500 mA cm −2 ) which are less than that of 2017 US DOE targets (≤30 mV loss). The durability studies indicated that the HCCs are promising cathode catalysts for transportation applications.