Nanotechnology for novel gas and photonic sensors
Unlike bulk materials, the properties of nanomaterials often depend on their size and shape as a large fraction of atoms lie on the surface. A given material can be prepared in different nanoforms such as nanoparticles, nanowires, nanoribbons or nanotubes and in different sizes. Even structure and composition in the nanoforms can be quite different from bulk. The EU-funded project NPS4FM (Nanomaterial photonic sensors for food manufacturing) paved new avenues for further exploring the use of nanomaterials as sensors in various applications. Scientists successfully prepared tin dioxide, zinc oxide (ZnO), cadmium oxide (CdO) and cadmium sulphide (CdS) nanostructures of different morphology via laser ablation in liquids. In some cases, the team applied surface engineering to add a passivation layer against corrosion. Using laser irradiation of solutions of liquid precursors, scientists synthesised branched CdS nanowires as thin as 24 nm in diameter and quasi-monocrystal CdS nanoboxes – both CdS nanostructures are the smallest CdS systems ever reported. Their unique morphology, large surface area and high-energy facets make these nanostructures suitable for photocatalysts. The unique morphologies and crystallite orientation of CdS and CdO nanoflakes were sufficiently leveraged to create new gas sensors with high sensitivity and selectivity towards isopropanol and diethyl ether. Porous silicon carbide ceramics were also developed that can potentially be used for gas sensors or catalyst supports. Employing a simple one-step synthesis method, scientists produced various ZnO and doped-ZnO nanocrystals of sizes well below 10 nm and uniform size distribution. The team showed that this new method can easily be scaled up, providing the opportunity to produce various nanocrystals that, upon processing in a new solvent, can be efficiently used as inks for spin-coating or printing devices. After some experimental tinkering with carbon dots, scientists managed for the first time to control their emission properties. Applying particular surface engineering techniques, the team obtained red, blue and green luminescence from these carbon dots. The easy preparation and unique optical features render these nanoparticles useful in light-emitting diodes, full-colour displays and multiplexed bioimaging. NPS4FM successfully accomplished the synthesis of a number of nanomaterials with important industrial applications. All pioneering experimental project activities and findings have been reported in peer-reviewed journals.
Keywords
Photonic sensors, printed electronics, nanomaterials, NPS4FM, gas sensors, carbon dots
