Redox-induced changes in nanostructures and electron densities of connected Pt–Fe catalysts for fuel cells revealed via in situ coherent X-ray diffraction

In a sustainable society, polymer electrolyte fuel cells are one of the promising energy devices for automobiles and residential uses because of their high energy efficiency. On the other hand, the current cathode catalysts are mainly made of precious metals such as Pt, and their activity and durability have become an issue for their widespread use. Carbon-free, connected Pt–Fe-alloy catalysts have been developed to solve this problem. However, their catalytic mechanism has not yet been clarified. In this study, redox-induced changes in the nanostructures and electron density distributions of the catalyst were investigated via coherent X-ray diffraction imaging.