Fabrication of nanoporous noble metal thin films by O₂ plasma dealloying

In this study, 300 nm thick nanoporous (np) noble metal thin films containing mesopores (2–50 nm) or macropores (> 50 nm) were fabricated by O₂ plasma dealloying of sputter-deposited noble metal-carbon thin films. Noble metal-carbon thin films of 500 nm thickness were deposited on Si wafer substrates, and the target power was controlled to obtain a proper compositional ratio. Subsequently, O₂ plasma dealloying was performed to selectively remove carbon atoms, thereby forming the np structure. Using this method, we successfully fabricated various np thin films of noble metals, such as Au, Ag and Pt.