Fabrication and characterization of nanoporous Ag–Pt alloy

Nanoporous Ag–Pt bi-metallic alloy was fabricated by free dealloying of amorphous Ag-based precursor with the nominal composition of Ag_38.25Pt_0.5Cu_38.75Si_22.5. The noble Ag and Pt were left after the less noble Cu and Si dissolved in a certain acid solution. Bi-continuous nanoporous microstructure was formed with asymmetric ligaments and pores with typically 30–200 nm in width. The trace addition of Pt has refined the grains of the ligaments to the average size of less than 20 nm in the substrate and induced the formation of rods with nanopores. The morphologies of the rods were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) both in the form of clusters and as scattered individuals with characteristic length of several micrometers and diameter of tens of nanometers. The grains sizes in the rods were finer than those in the ligaments. The good mechanical integrity might be due to the combination of continuous ligaments and clusters of rods.