Nanoporous Cu dealloyed from intermetallic MgCu2 and its catalytic properties in formaldehyde oxidation reaction

Abstract

Nanoporous Cu (np-Cu) has recently been considered for use in a variety of functional materials, such as catalysts and sensors, due to its advantages such as excellent electrical conductivity, chemical reactivity, and high specific surface area. Furthermore, research has shown that np-Cu can be successfully fabricated using a dealloying method utilizing selective leaching of sacrificial elements in the precursor, which is much simpler than other nanostructuring techniques such as templating or laser etching. However, cracking due to volume shrinkage during the dealloying process is known to negatively impact not only the mechanical properties of np-Cu but also its functional performance. The most intuitive and effective way to suppress cracking during the dealloying process is to reduce the degree of volume shrinkage by lowering the relative proportion of the sacrificial element in the precursor. For example, when applying an Al–Cu alloy precursor to the dealloying process, the relative proportion of the sacrificial element Al must be maintained at 50 at.% or higher to ensure the formation of a nanoporous structure throughout the entire region. However, the authors have discovered that when an intermetallic MgCu2 precursor is applied to dealloying, the relative proportion of Mg, which acts as a sacrificial element, can be reduced to 33 at.%, resulting in significantly reduced cracking induced by volume shrinkage. In this study, the structure and mechanical properties of np-Cu dealloyed from MgCu2 are comparatively investigated with those of np-Cu samples dealloyed from other precursor materials in the literature, and the catalytic properties of the new type of np-Cu in the formaldehyde oxidation reaction (FOR) are also presented to explore its potential for functional applications.