Fabrication of Metallic Nanoporous Films by Selective Chemical Etching

The objective of this study is to synthesize and characterize different nanoporous structures by chemical etching. The experiments were conducted on three different materials: We treated 6 carat white gold (Au/Ag alloy, 1:3 ratio by weight) with 70{\%} HNO$_{3}$ to grow Au nanoporous, the 50/50 solder wire (Pb/Sn alloy) with 93{\%} H$_{2}$SO$_{4}$ to create Pb porous and Imitation Italian gold leaf (Cu/Zn alloy, 82/18 by wt. {\%}) with NaOH solution (5 gm NaOH per 100 ml distilled H$_{2}$O) for Cu porous. The free-standing porous films have been analyzed by scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), high quality x-ray mapping (XRM). We observed the composition of the porous materials at every stage of chemical dealloying and conducted tests with different process parameters to optimize the size of self-ordered porous structures. Our experiments resulted in sponge like Au nanoporous of 10-200 nm, Pb pores of 10-300 nm and Cu pores of 10-150 nm. The results showed a technically improved fabrication of different nanoporous materials with high surface area and well defined pore morphology.