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

Direct ethanol fuel cells (DEFC) are regarded as 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 (EOR). To further enhanced the catalytic performance of the catalyst, it's necessary to improve the mass activity and utilization efficiency of Pt. In this work, we report a strategy for fabricating ordered mesostructured platinum-palladium (PtPd) 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 20k cycles of accelerated durability test for ORR, MPPNs exhibit an impressive retention of their original mass activity, maintaining a value of 93.9%. Furthermore, MPPNs display superior catalytic activity and stability for ethanol oxidation reaction, with a mass activity about 2.4 times higher than that of commercial Pt/C. After the 2000 scan cycles, the mass activity still remains 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.