Hybrid cathode catalyst with synergistic effect between carbon composite catalyst and Pt for ultra-low Pt loading in PEMFCs

- The electrochemically active CCC is synthesized by a facile bi-metallic chelation.
- CCC with abundant pyridinic and quaternary nitrogen sites exhibits high activity towards the oxygen reduction reaction.
- The pyridinic nitrogen plays an important role of the oxide-cleanser for Pt.
- Pt nanoparticles are uniformly deposited on CCC as compared to CB.
- The hybrid cathode catalyst exhibits superior activity to Pt/CB.

Due to the high cost of Pt catalyst, reducing the amount of Pt in electrodes is one of the primary issues in polymer electrolyte membrane fuel cells. In this study, the hybrid cathode catalyst using the electrochemically active carbon composite catalyst and Pt catalyst is developed in order to reduce the amount of Pt and increase the overall catalytic performance. The carbon composite catalyst (CCC) is synthesized by pyrolysis of Fe-Co chelate compound followed by acid leaching. The current density of Pt/CCC is 1.5-6-fold higher than that of Pt/CB when employing ultra-low Pt loading (0.04 mgPt cm−2). It is found that the Pt/CCC with the ultra-low Pt loading at tuned operating conditions exhibits a higher fuel cell performance than the Pt/CB and commercial Pt/C with four times higher Pt loading (0.16 mgPt cm−2). The extensive activity of Pt/CCC is ascribed to the synergistic effect through (1) the combined activity of catalytic sites present in the CCC support and Pt, (2) the well-distributed nanoparticles and (3) the increased metallic Pt0 concentration which indicated that the pyridinic-N played a role of oxide-cleanser.

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