Cathodes for High‐Temperature PEM Fuel Cells Based on a Si 0.97 Al 0.03 C Promoter and a Sn 0.95 In 0.05 P 2 O 7 Ionomer

This paper presents a promising approach to reduce the quantity of Pt required in cathodes for high‐temperature proton exchange membrane (PEM) fuel cells. Based on preliminary experiments, thermally stable Si 0.97 Al 0.03 C and Sn 0.95 In 0.05 P 2 O 7 were selected as promoter and ionomer, respectively. Si 0.97 Al 0.03 C particles (∼40 nm) and Sn 0.95 In 0.05 P 2 O 7 particles (∼45 nm) were successfully produced on a carbon support. Pt particles (∼9 nm) were selectively impregnated in the vicinity of the ionomer. Polarisation measurements revealed that the Pt‐Sn 0.95 In 0.05 P 2 O 7 ‐Si 0.97 Al 0.03 C/C cathode exhibited much higher oxygen reduction reaction (ORR) activity than that observed for a pure Pt/C cathode, due to the enhanced dissociative oxygen adsorption on the Si 0.97 Al 0.03 C particles and the increased number of reaction sites for the ORR provided by the Sn 0.95 In 0.05 P 2 O 7 particles. Fuel cell operation tests demonstrated that a Pt‐Sn 0.95 In 0.05 P 2 O 7 ‐Si 0.97 Al 0.03 C/C cathode with a low Pt loading of 0.1 mg cm –2 provides better cell performance than a Pt/C cathode with a Pt loading of 1.0 mg cm –2 .