Formation of Monolithic Nanoporous Copper with Ultrahigh Specific Surface Area through Chemical Dealloying of Mg-Cu Alloy

摘要

The monolithic nanoporous copper (NPC) with ultrahigh specific surface area can be achieved throughchemical dealloying of melt-spun Mg 12 at.% Cu alloy comprising Mg and Mg2Cu phases in anacidic solution at room temperature. The microstructure of the monolithic NPC ribbons wascharacterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis,transmission electron microscopy, and high-resolution transmission electron microscopy. Theexperimental results show that the melt-spun Mg 12 at.% Cu alloy can be totally dealloyed, resulting inthe formation of uniform-structured NPC ribbons with relatively large pore sizes compared with that ofligament dimensions. This can be well explained as a consequence of a combination of the synergeticdealloying of Mg and Mg2Cu in the dual-phase Mg-Cu alloy and the fast surface diffusion of Cuatoms along alloy/solution interfaces during dealloying. Meanwhile, we found cracking to beunavoidable in the as-dealloyed samples, indicating the 12 at.% Cu content in the Mg-Cu alloy systemis the lowest limit of Cu concentration to obtain the monolithic NPC, below which cracks will extendfast causing the collapse of porous structures. Based upon its special structure features, the Brunauer- Emmett-Teller (BET) surface area of the monolithic NPC is much high and can be determined to be2 -1 34.7 0.1 m g , which would be especially beneficial for sensing and actuating applications.