Formation of nanoporous noble metal thin films by electrochemical dealloying of Pt _xSi _1-x

We demonstrate the synthesis of nanoporous Pt thin films on Si by electrochemical dealloying. Amorphous Ptx Si1-x films (∼100-250 nm thick) are formed by electron beam codeposition and dealloyed in aqueous HF solutions at an electrochemical potential sufficient to selectively remove Si while allowing self-assembly of Pt into a nanoporous structure. The Pt nanoporous layers have a pore size of 5-20 nm, ligament thickness ∼5 nm, a surface area enhancements >20 times, and an ultrafine grain polycrystalline microstructure.