Controlled porosity and pore size of nano-porous gold by thermally assisted chemical dealloying - a SAXS study

Nano-porous metals offer great potential for applications such as bio-sensors, chemical reactors, platforms for cell growth, and media for separation because of their high surface area and reactivity at the nanoscale. The high surface to volume ratio of nano-porous metals also offers advanced plasmonic properties which may be put to use upon refining the control over pore size distributions in the nanoscale range. Here, the impact of the solution temperature on the nature of both ligaments and pores generated across ultra-thin AuAg50 metal leaves by chemical dealloying is demonstrated for the first time. The pores were found to be controllably tuneable within a range from 30 to 54 nm in diameter after 75 min of treatment in an etching solution with a temperature between 5 and 60 °C. The kinetics of the pore formation was studied by an in situ dealloying experiment on the small angle X-ray scattering beamline at the Australian Synchrotron and specific materials properties were thereafter cross-correlated to ex situ morphological experiments. This work demonstrates a straightforward new method to refine porous structures at the nanoscale and fine-tune surface properties across nano-porous metals that will extend their applications.