Fabrication of nanoporous metals by dealloying of ternary alloys: evaluation of electrocatalytic properties

Novel nanoporous structures have been formed by electrochemical dealloying of ternary precursors (i.e., Ag-Au-Pt with a platinum content of ca. 1, 2 and 4 at.% and 77 at.% of silver) in acidic media. Dealloying is a common corrosion process in which the less-noble element is selectively dissolved from the metallic solid solution, leaving behind a nanoporous sponge composed almost entirely of the more noble alloy constituents. The presence of Pt, even in such a small concentrations, reduces the feature size of the nano-structure(< 7 nm), minimizes coarsening of the porosity and helps preserve the structural integrity of the structure. Furthermore, these structures show greater catalytic activity for methanol electrooxidation reaction in alkaline solutions, if compared with the nanoporous structure formed from Ag-Au alloy (77 at.% of silver). This enhancement is exemplified by a broad and high anodic peak during the positive scan and two secondary oxidation peaks in the subsequent reverse scan.