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

摘要

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 electro-oxidation 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.