Due to localized surface Plasmon resonance, Gold nanoparticles/nanostructures exhibit an absorbance maximum, typically in visible region of ~520-600nm. Wavelength for maximum absorbance is dependent on shape, size and placement nanoparticles as well as the refractive index of its surrounding. Change in absorbance maximum in response to refractive index change has been exploited extensively for biosensing. Now Bengt Kasemo group at Chalmers has used the same property to study the heterogeneous catalytic reaction at the catalyst surface.
The sensor is simple in its implementation- it consist of array of gold nanodisk covered with thin coating of catalyst support surface on which Platinum (Pt) catalyst is deposited. Absorbance spectra of the sensor are collected and shift in maximum wavelength is observed as the catalytic reaction takes place on solid nanometer sized catalyst.
To detect oxidation of hydrogen to water and oxidation of carbon monoxide to carbon dioxide they designed a sensor consisted of an array of gold nanodisk (76nm in diameter and 30nm in height) covered with 10nm of SiO2 on which 5-20nm Pt particles are deposited. Another sensor was created for storage and reduction of NOx by using arrays of gold disks (140nm diameter, 30nm height) coated with thin layer (~30nm) of BaO on which nanogranules of Pt is deposited.
Considering the track record of Prof Kasemo- he is one of the key figures in development of Quartz Crystal Microbalance Biosensor and founder member of the company q-sense- it may not be surprising to see plasmonic sensors hit the market shelves pretty soon.