Ultrathin Pt-Ag Alloy Nanotubes with Regular Nanopores for Enhanced Electrocatalytic Activity

While creating open nanostructures represents a popular strategy for improving the utilization efficiency of Pt-based catalysts for electrochemical reactions, the exposed facets should be precisely controlled for further enhancement of the catalytic activity. Here, we report a novel strategy for creating regularly shaped nanopores in ultrathin nanotubes of bimetallic noble metals. By templating against Ag nanowires and then applying a thermal ripening process, we have successfully produced ultrathin (with a wall thickness of ∼1 nm) Pt-Ag alloy nanotubes containing high-density well-defined rectangular nanopores and a collapsed double-layer structure. The resulting porous nanotubes expose {100} facets at the basal sides and {110} facets with step sites at the edges of the rectangular nanopores. The particular surface structure and the bimetallic composition enable suppressed CO poisoning of the catalysts and consequently enhanced electrocatalytic activity in the methanol oxidation reaction. The typical specific and mass activities are 6.63 mA cm^-2 and 2.08 mA (μg of Pt)^-1, respectively, in an acidic medium, superior to the values of commercial Pt/C and many previously reported catalysts. We believe this work opens new opportunities in the design of noble metal open nanostructures for enhanced performance in a broad range of catalytic applications.