2-D organization of silica nanoparticles on gold surfaces: CO 2 marker detection and storage.

A single layer of silica nanoparticles with an average size of ∼200 nm was deposited over the surface of pristine gold wafers, aided by (3-mercaptopropyl)trimethoxysilane. The nanoparticle immobilization was driven by covalent bonding rather than a self-assembly process, leading to a cluster-assembled material which has CO 2 sensing features. Here, we show how this device can be used for CO 2 physisorption and chemisorption. We analyse the device, both spectroscopically and morphologically, before and after exposure to an atmosphere of 7 mbar of CO 2 , inside a planetary atmospheres and surfaces simulation chamber, (PASC) mimiking Martian atmospheric conditions. Our studies demonstrate that these clusters are suitable for CO 2 detection and storage, under well controlled experimental Martian conditions. Their high sensitivity at a very low concentration of CO 2 , 12.4 ppm, makes them ideal candidates in the nanosensor field.