Mesoporous Gold Coatings
Ultra-high resolution image of mesoporous gold film, showing 12 nm diameter pores

Ultra-high resolution image of mesoporous gold film, showing 12 nm diameter pores

The next project is a development of UTS' interest in vacuum-deposited metallic coatings for spectral control on windows. However, instead of applying continuous or granular coatings of metals, we develop a mesoporous metallic coating on the surface of the glass by de-alloying vacuum-deposited AuAl2 coatings in aqueous solutions of NaOH; a process based on a patent by Cortie. Due to its relative chemical inertness, gold is one of the very few metallic elements that can be formed into stable mesoporous structures, which have a very high surface area. Such coatings are highly absorptive and have unusual optical properties across the visible and infra-red parts of the spectrum.

Prototype electrochemical ultracapacitor made at UTS using mesoporous gold

Prototype electrochemical ultracapacitor made at UTS using mesoporous gold

In particular, they have an almost flat spectral characteristic deep into the infra-red, which is unlike that of either conventional metallic or insulating materials. In addition, Cortie has demonstrated with support from the World Gold Council in London that these coatings can exhibit electrochemical capacitance. Large capacitances (up to 2mF/cm2) were shown, primarily because of the hugely increased specific surface area of this material. A prototype device made at UTS is shown to the right.