Seiji Nakashima

Hydrogen polymer electrolyte fuel cells (PEFCs) are key technologies for achieving a low-carbon society, but conventional oxygen reduction reaction (ORR) catalysts sucg as Pt/C suffer from degradadation of carbon supports during operation. To overcome this limitation, we developed a nanostructured catalyst support by coating tin oxide (SnO2) nanoparticles with cobalt-manganese oxide (CMO), enabling nanoscale interface engineering. The CMO layer was formed via electroless deposition of cobalt-manganese oxyhydroxide (CMOH) followed by thermal conversion at 300 °C. Platinum (Pt) and carbon black (Ketjenblack®, KB) were then incorporated to obtain Pt-CMO-SnO2/KB. The resulting catalyst exhibited a 1.97-fold higher mass activity (119.9 A gPt-1 at 0.9 V) than conventional Pt/C and showed significantly enhanced durability, retaining 33% more mass activity after voltage cycliying. Scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDX) revealed selective Pt deposition on the CMO surface rather than on carbon. X-ray photoelectron spectroscopy (XPS) further confirmed strong metal-support interactions that suppressed Pt agglomeration and detachment. This nanointerface-guided design provides as effective and scalable strategy for improving ORR activity and durability in next-generation PEFC catalysts.