Nanoporous surface fabricated on metal sheets by alloying/dealloying technique

An alloying/dealloying technique including stacking rolling was used to fabricate nanoporous architecture on Au sheet surface. Under appropriate conditions, a nanoporous surface layer with a thickness of 150-250 nm was generated. The extended immersion of the sample in the electrolyte (HNO₃) increased the ligament size of the nanoporous architecture up to 41 nm. Cross-sectional observations suggested that the nanoporous surface layer can be seamlessly bonded to the bulk substrate Au. True surface area, which was measured by an electrochemical method, decreased as ligament size increased by the extended immersion. The relationship among surface area, ligament size and volume shrinkage was investigated.