The Mechanism and Applications of Nanoporous Gold Derived from Dealloying Au-based Metallic Glass


Student thesis: Doctoral Thesis

View graph of relations



Awarding Institution
Award date5 Oct 2018


Dealloying, through which an active element was selectively dissolved away from an alloy, is an important means to fabricate nanoporous structures for a variety of applications. However, current fabrication methods of nanoporous gold (NPG) mainly rely on dealloying Ag-Au binary crystalline precursors, typically Ag65Au35, with the “dealloying threshold” or “parting limit” above 55 at%. Here we report a simple chemical dealloying process, through selective dissolution of one element from a Au55Cu25Si20 bulk metallic glass with low ‘parting limit’, and a novel peculiar three-dimensional ‘cone shaped protrusion’ nanoporous structure which has never been reported before. In this structure, a metastable gold silicide formed in the initial dealloying stage was decomposed into gold nanoparticles and amorphous SiOx in the later coarsening stage. Our finding provides insights into the underlying relationship between ‘parting limit’ and atomic level structure of metallic glass. Comprehensive discussions on the porosity evolution stages as well as the correlation between the porous ‘cone shaped protrusion’ development and potential energy landscape are made in this thesis.

Owing to the bi-continuous ligaments and voids space of NPG structure and high specific surface area (maximum ~31m2g-1) associated with a novel porous ‘cone shaped protrusion’ morphology, the highest specific activity of MOR catalytic performance of NPG catalyst so far was reported. In addition, taking advantage of this excellent structural feature of the NPG, a nanoporous Pd catalyst (NPG@Pd) thin film was fabricated on the NPG substrate. The NPG@Pd catalyst exhibited greatly enhanced MOR performance (maximum MOR specific activity 2.14mA/cm2). We attribute the enhancement of MOR activity to the increase of active sites as well as the modification of surface composition and electronic structure due to migration of Au to the Pd thin film layer. Furthermore, the dealloyed surface containing cone-shaped protruding micro-islands provided multiple reflections and numerous fine interstices to produce hot spots for SERS enhancements. The SERS signal of analyte, p-aminothiophenol, in the micro-island region of dealloyed Au-based metallic glass was about 2 orders of magnitude larger than that of flat Au film.

    Research areas

  • Nanopores, De-alloying, Metallic glasses, Mechanism, Evolution