Investigation On Photonic And Electrical Sensing Properties Of One-Dimensional Hybridized Nanomaterials And Their Applications In Environmental Detections

As new carbon materials, Single-Walled Carbon Nanotubes (SWCNTs) have attracted great interests recently due to their unique chemical and physical properties. Particularly, applications of SWCNTs based on electrical properties are being widely investigated, which lead to their considerations as replacements for Si in future generation devices. Considered that SWCNTs can be well compatible with conventional field-effect transistor (FET) architectures, SWCNT-FET with quasi-one-dimensional electronic structures and very high surface-to-volume ratios can be expected as excellent electronic nanodevices compared to tranditional sensors.On the other hand, the unique optical properties of gold nanostructures also attract a great deal of attention due to their potential applications in organic-inorganic composites, photonics, biomaterials, and biomedicine. It should be noted that intensity and wavelength of surface plasmon resonance (SPR) of one-dimesional gold nanoparticles (Gold Nanorods), viz., coherent oscillations of the metal electrons in resonance with light of a certain frequency, are highly sensitive to the surrounding environment, which can be utilized for surface enhanced Raman scattering (SERS) sensing purposes. Strong enhancement of the electromagnetic field owing to the excitation of the surface plasmons at the surface of particles have been extensively studied for sensing applications.In summary, sensing hybridized materials of SWCNTs and Gold Nanorods (GNRs) can be expected as excellent candidates to manufacture future generations of chemical sensors. In this dissertation, hybridized SWCNTs or GNRs have been prepared and employed to fabricate sensing devices, which display excellent sensitivity and selectivity. The main conclusions are summarized as follows:(1) Two novel compounds, N-4-Hexafluoroisopropanolphenyl-l-pyrenebutyramide (HFIPP) and p-hexafluoroisopropanol aniline (HFIPA) have been prepared for the first time. After functionalized with SWCNTs, two new hybridized materials SWCNT-HFIPP and SWCNT-HFIPPH have been obtained. Considered that strong hydrogen-bonding can be formed between hexafluoroisopropanol groups and dimethyl methylphosphonate (DMMP) (simulant of nerve agent sarin), two hybridized material sensing devices have been fabricated and utilized to detect DMMP. Excellent sensitivity and selectivity of the hybridized devices suggest that they have great capability of detecting explosives and chemical warfare agents.(2) Novel SWCNT-PCD hybrids have been successfully synthesized through in situ diazonium reaction between mono-6-deoxy-6-(p-aminophenylamino)-β-cyclodextrin (PCD) and SWCNTs for the first time. The cyclodextrin (CD) groups bind to the SWCNT surfaces through covalent interactions. Based on the sensing materials, fabricated chemical sensors of SWCNT-PCD hybrids have been utilized to detect Persistent Organic Pollutants (POPs), which exhibit excellent sensitivity and selectivity due to the concept of molecular recognition. The equilibrium constant values for the complexation of the PCD with the different POPs correlate with the magnitudes of the conductance change ratios of the SWCNT-PCD devices after binding of these POPs molecules, which can be suggested as potential applications in environmental monitor.(3) The as-prepared GNRs with different aspect ratios have been decorated with mono-6-thio-β-cyclodextrin so as to efficiently capture and detect methyl parathion insecticide via surface enhanced Raman scattering (SERS) technique for the first time. Detailed comparison among different aspect ratios of the GNRs suggests that the GNRs with aspect ratio 2 can be provided as excellent SERS active substrate for detecting the insecticide in the present study. Due to efficient formation of host-guest between hybridized cavity and methyl parathion, identification of the insecticide can be observed at picomolar level according to the fingerprint Raman peaks. Excellent sensitivity and selectivity for detection of the insecticide using the hybridized GNRs without Raman label indicate that it is a simple and ultrasensitive approach for detecting insecticides in contrast with some other traditional detection approaches.