Nanoporous Copper Ribbons Prepared by Chemical Dealloying of a Melt-Spun ZnCu Alloy
Sawsan Ibrahim, Alexandra Dworzak, Daniel Crespo, Frank Uwe Renner, Carsten Dosche, Mehtap Oezaslan
Abstract
Dealloying is a powerful and versatile method to fabricate three-dimensional nanoporous (np) materials with high surface area. In this work, we investigated the dealloying processes of Zn80Cu20 alloy ribbons in acidic and alkaline environments. Our results show that the nanostructure can be controlled by varying the nature of electrolyte solution, pH value, dealloying time, and temperature. In acidic media, the presence of chloride ions enhances the Cu surface mobility, leading to a faster coarsening and growth of ligaments during the dealloying process over time. In contrast, the surface diffusivity of Cu atoms in alkaline media is three orders lower than that in acid and results in a remarkably smaller ligament size due to the formation of Cu (hydr)oxide surface species. Cross-section analysis indicates that the dealloying process is largely controlled by interfacial processes. Interestingly, local Zn-rich regions were found near the surface in np-Cu ribbons dealloyed in 0.1 M HCl. This comprehensive study shows the influence of dealloying conditions on the morphology and residual Zn content of np-Cu ribbons as a model system for fabricating bicontinuous ligament-pore network materials with tailored structural and chemical properties for applications in electrochemical synthesis, sensors, and catalysis.