Time-dependent power law function for the post-dealloying chemical coarsening of nanoporous gold derived using small-angle X-ray scattering

Dealloyed nanoporous gold spontaneously coarsens when exposed to moderate temperatures (thermal coarsening), or to non-inert gases or liquids at room temperature (chemical coarsening). Although considerable research has been done on post-dealloying thermal coarsening, little attention has been paid to post-dealloying chemical coarsening, occurring not during, but after dealloying. Here, we use small-and wide-angle X-ray scattering (SAXS/WAXS) techniques to study the post-dealloying chemical coarsening behavior of dealloyed nanoporous gold samples aged in nitric acid over the course of 6 days at room temperature. A quantitative relationship between the ligament size and coarsening time is derived. Typically, our SAXS data reveals that the ligament size in nanoporous gold chemically coarsens according to a-1/4 time-dependent power law, which is characteristic of a surface diffusion-dominated process. The derived relationship between the ligament size and coarsening time will guide the design of nanoporous gold with desired structure size to optimize its (electro)chemical properties. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Dealloyed nanoporous gold spontaneously coarsens when exposed to moderate temperatures or non-inert gases or liquids at room temperature. This study focuses on post-dealloying chemical coarsening behavior of aged nanoporous gold samples in nitric acid at room temperature, revealing a time-dependent power law relationship between ligament size and coarsening time. The findings will guide the design of nanoporous gold with desired structure size for optimizing its (electro)chemical properties.