In proton exchange membrane fuel cells (PEMFCs) operating with the use of Pt/carbon (Pt/C) cathode catalysts, severe corrosion of the carbon support has been recognized at high potentials. The improvement of the catalyst durability with high activity is required for heavy use applications. Alternative candidate catalysts with high durability and high activity are Pt catalysts supported on non-carbon ceramic supports ^[1,2]. Our group confirmed that Pt catalysts supported on SnO₂ (Pt/M-SnO₂, M = Nb, Ta) without carbon additive were superior in durability (startup/shutdown, load cycling) and oxygen reduction reaction (ORR) activity to those of commercial Pt catalysts, e.g., supported on either graphitized carbon black (Pt/GCB, TEC10EA30E, TKK) or carbon black (Pt/CB, TEC10E50E, TKK), by evaluation of membrane-electrode assemblies (MEA) ^[3-9]. The non-carbon support of SnO₂ nanoparticles has a unique carbon-like microstructure consisting of a fused-aggregate network structure, which enhances the electronically conducting pathways via the aggregated microstructure and gas diffusion pathways via the open pores in the microstructure. We have also proposed ways to design the Pt nanorod supported on the Nb-SnO₂ based on the catalyst design concept (Fig. 1)^[10]. The cell performance using the Pt/SnO₂ cathode catalyst layers at operating temperatures from 80^oC to 120^oC is quite promising for the development of high-power density (Fig. 2) with simultaneous high durability.

Acknowledgments

This work was partially supported by funds for the project “Electrolytes, Catalysts and Catalyst layers with Extraordinary Efficiency, power and Durability for PEFCs-2030 (ECCEED’30) from the New Energy and Industrial Technology Development Organization (NEDO) of Japan, and JSPS KAKENHI Grant Number (20H02839) from the Ministry of Education, Culture, Sports, Science and Technology.

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