Photonic gas sensors exploiting directly the optical properties of hybrid carbon nanotube localized surface plasmon structures

We investigate the modification of the optical properties of carbon nanotubes (CNTs) resulting from a chemical reaction triggered by the presence of a specific compound (gaseous carbon dioxide (CO2)) and show this mechanism has important consequences for chemical sensing. CNTs have attracted significant research interest because they can be functionalized for a particular chemical, yielding a specific physical response which suggests many potential applications in the fields of nanotechnology and sensing. So far, however, utilizing their optical properties for this purpose has proven to be challenging. We demonstrate the use of localized surface plasmons generated on a nanostructured thin film, resembling a large array of nano-wires, to detect changes in the optical properties of the CNTs. Chemical selectivity is demonstrated using CO2 in gaseous form at room temperature. The demonstrated methodology results additionally in a new, electrically passive, optical sensing configuration that opens up the possibilities of using CNTs as sensors in hazardous/explosive environments

High-throughput screening of metal-porphyrin-like graphenes for selective capture of carbon dioxide

Nanostructured materials, such as zeolites and metal-organic frameworks, have been considered to capture CO2. However, their application has been limited largely because they exhibit poor selectivity for flue gases and low capture capacity under low pressures. We perform a high-throughput screening for selective CO2 capture from flue gases by using first principles thermodynamics. We find that elements with empty d orbitals selectively attract CO2 from gaseous mixtures under low CO2 pressures (similar to 10(-3) bar) at 300 K and release it at similar to 450 K. CO2 binding to elements involves hybridization of the metal d orbitals with the CO2 pi orbitals and CO2-transition metal complexes were observed in experiments. This result allows us to perform high-throughput screening to discover novel promising CO2 capture materials with empty d orbitals (e.g., Sc- or V-porphyrin-like graphene) and predict their capture performance under various conditions. Moreover, these findings provide physical insights into selective CO2 capture and open a new path to explore CO2 capture materialsopen

Hybrid effects in graphene oxide/carbon nanotube-supported Layered Double Hydroxides: Enhancing the CO₂ sorption properties

Graphene oxide (GO) and multi-walled carbon nanotubes (MWCNT) have been previously used independently as active supports for Layered Double Hydroxides (LDH), and found to enhance the intrinsic CO₂ sorption capacity of the adsorbents. However, the long-term stability of the materials subjected to temperature-swing adsorption (TSA) cycles still requires improvement. In this contribution, GO and MWCNT are hybridized to produce mixed substrates with improved surface area and compatibility for the deposition of LDH platelets, compared to either phase alone. The incorporation of a robust and thoroughly hybridized carbon network considerably enhances the thermal stability of activated, promoted LDH over twenty cycles of gas adsorption-desorption (96% of retention of the initial sorption capacity at the 20th cycle), dramatically reducing the sintering previously observed when either GO or MWCNT were added separately. Detailed characterization of the morphology of the supported LDH, at several stages of the multicycle adsorption process, shows that the initial morphology of the adsorbents is more strongly retained when supported on the robust hybrid GO/MWCNT network; the CO₂ adsorption performance correlates closely with the specific surface area of the adsorbents, with both maximized at small loadings of a 1:1 ratio of GO:MWCNT substrate