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[Display omitted] • Providing a highly active and stable PdPt catalysts with unique porous structure. • Designing correlative methodology including ADT, IL-imaging, in situ XAFS, MP-AES and DFT calculations. • Tracing dynamic structural evolution of PdPt alloy during electrochemical degradation in both theory and experiment. • Establishing an accurate structure-performance relationship of PdPt catalysts under ORR reaction conditions. Proton exchange membrane fuel cells require oxygen reduction catalysts with high activity and stability. Pt based alloy materials are most widely applied ORR catalyst due to its high intrinsic activity, but usually suffer from rapid deactivation as a result of particle agglomeration, detachment, Ostwald ripening and/or Pt dissolution. Here we investigate the degradation of the PdPt alloys via in situ X-ray absorption fine structure, Δ μ analysis, identical location-electron microscopy and DFT calculations. We conclude that the origin of high activity and stability of the PdPt catalyst stems from the oxidation resistance of metallic Pt, forming mainly surface adsorbed O species at high potentials. Two stage degradation process are observed, showing an evolution of dynamic surface dependent ORR performance along with the deactivation process. The careful design of Pt alloy structure leads to controlled surface oxygen behaviours. This opens a new way to increase the lifespan of fuel cells and improve the Pt utilization efficiency. [ABSTRACT FROM AUTHOR]

In this work, a metastable aqueous interface was fabricated for synthesizing mesoporous and high surface area MnO 2 . When urea was used as the additive, hierarchical spheres self-organized from ultrathin nano-sheets were obtained. Its porous structure could be controlled through adjusting the urea concentration, and a maximum surface area of 407 m 2 g −1 was achieved by this method, which is larger than the reported values. Due to the porous structure and high surface area, as-prepared MnO 2 exhibited a specific capacitance of 775.4 F g −1 at a current density of 0.1 A g −1 , and exhibited a 63.5% capacitance retention when the current density was increased from 0.1 A g −1 to 5 A g −1 . Durability studies showed a 63.7% capacitance retention after 2500 cycles. The metastable interfacial reaction approach could also be extended to other alloys with large surface area and porous structure, such as CoB alloy. This method provides a simple and low-cost method to synthesize high surface area and mesoporous materials. [ABSTRACT FROM AUTHOR]