Dealloying to Nanoporous Silver and Its Implementation as a Template Material for Construction of Nanotubular Mesoporous Bimetallic Nanostructures

Nanoporous silver (NPS) is fabricated by selectively dissolving Al from AgAl alloys in corrosive electrolytes at room temperature. Electron spectroscopy characterizations demonstrate that the NaOH electrolyte is beneficial to the formation of a threedimensional bicontinuous porous nanostructure with uniform and tunable pore and ligament dimensions of a few tens of nanometers, while processing in HCl electrolyte easily lead to coarsened porous nanostructures. The high-surface-area Ag nanostructures are demonstrated as novel effective template materials to the construction of nanotubular mesoporous Pt/Ag and Pd/Ag alloy structures, which are realized via room temperature galvanic replacement reactions with H2PtCl6 and K2PdCl4 solutions by adding a high concentration of Cl- ions as a coordinating agent. Electrochemical measurements indicate that the resulting hollow and porous bimetallic nanostructures show enhanced electrocatalytic activities and CO-tolerance with better durability toward methanol and formic acid oxidation due to alloying with Ag.