Formation of nanoporous noble metal thin films by electrochemical dealloying of PtxSi1−x

We demonstrate the synthesis of nanoporous Pt thin films on Si by electrochemical dealloying. Amorphous PtxSi1−x films (∼100–250nm 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 5–20nm, ligament thickness ∼5nm, a surface area enhancements 20 times, and an ultrafine grain polycrystalline microstructure.