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 (similar to 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 similar to 5 nm, a surface area enhancements > 20 times, and an ultrafine grain polycrystalline microstructure. (c) 2006 American Institute of Physics.