Mesostructured Pt alloy nanotubes with synergistic edge sites as bifunctional electrocatalysts for direct ethanol fuel cells

Direct ethanol fuel cells are considered indispensable and prospective energy storage devices due to their high volumetric energy density. Platinum (Pt) and Pt-based alloys are regarded as the most effective catalysts for both oxygen reduction reaction (ORR) and ethanol oxidation reaction. To further enhance the catalytic performance of the catalyst, it is necessary to improve the mass activity and utilization efficiency of Pt. In this work, we report a strategy for fabricating ordered mesostructured platinum-palladium alloy nanotubes (MPPNs) with high hierarchical porosity (68%) and abundant exposed active edge sites. MPPNs exhibit excellent catalytic activity and stability for ORR, with a mass activity approximately 7.4 times higher than that of the commercial Pt/C catalyst. After 20 k cycles of accelerated durability test for ORR, MPPNs demonstrate impressive retention of their original mass activity, maintaining a value of 93.9%. Furthermore, they display superior catalytic activity and stability for ethanol oxidation reactions, with a mass activity about 2.4 times higher than that of commercial Pt/C. After the 2,000 scan cycles, the mass activity remains at 84.5% of initial performance. Both experimental and theoretical studies reveal that the synergistic effect of neighboring (111) and (100) facets on the edge sites plays a critical role in enhancing the electrocatalytic selectivity, activity and stability.