Studies On The Electronic Properties Of Carbon Nano-hybrid Materials

Nanoscale hybrid materials based on graphene and carbon nanotube were designed and fabricated, and their electronic and electrochemical properties were studied. The main hybrid materials under investigations includeβ-CD/graphene hybrid and double stranded-DNA/single walled carbon nanotubes conducting polymer nanocomposite. The structural, electronic properties of the obtained nanocompostie structures were characterized to explore their potential applications in the fields like conductive flexible electronic devices, solar cells and biosensors. Meanwhile, crossed-wire tunnelling junction and STM break junction apparatus were setup for molecular electronic investigation.The main results are as below:1. Novel nanohybrid (β-CD/GS) containing graphene sheet noncovalently modified byβ-cyclodextrin (β-CD) has been prepared, and theβ-CD/GS modified glassy carbon electrode (β-CD/GS/GCE) was used to detect the electrochemical response of dopamine (DA). Compared with bare glassy carbon electrode (GCE) and pure graphene sheet modified GCE (GS/GCE), theβ-CD/GS/GCE showed lower detection limit, and wider linear range in the detection of DA with more reversible and stable electrode reaction. Theβ-CD/GS/GCE also showed good capability to suppress electrochemical background of large excess ascorbic acid (AA). The results demonstrate the potential ofβ-CD/GS composite as an excellent material for the fabrication of novel electrochemical biosensors suitable for in vivo application.2. Nanocomposite structure containing covalently linkedβ-cyclodextrin and graphene sheets (β-CD/GS) was successfully fabricated, and its electrochemical properties were investigated. It was found that the defects on graphene sheets play an important role on the electrochemical catalysis properties of the composite materials. The adsorbedβ-CD helped to increase the separation between grapheen sheets so that the effective area is increased, hence give the improved catalytic effect. In the contratry, whenβ-CDs are covalently bonded to graphene surface, the defects has been occupied byβ-CD so that catalytic effect is decreased.3. Double stranded DNA functionalized single walled carbon nanotubes (ds-DNA/SWNT) has been fabricated. The ds-DNA/SWNT shows high capability of catalyzing in-situ fabrication of boronic acid doped polyaniline nanocomposite (PABA/ds-DNA/SWNT) by oxidation polymerization. We demonstrated that the polymerization process can be 4,500 times faster in the presence of ds-DNA/SWNT. Furthermore, the catalytic efficency can take place under neutral condition which may enable potential applications in biological research. PABA/ds-DNA/SWNT has a conductance five orders of magnitude higher compared to the ds-DNA/SWNT network, which show potential applications in flexible electronic devices and biological research.4. Crossed-wire tunnel junction and STM break junction apparatues have been set up to characterize the electronic conductance of organic molecule wires. The two apparatues were used to measure the electronic properties of high conjugated OPE molecules. Experimental results suggested that the junctions are stable and reproducible, which allow reliable conduction measurement at nanoscale or single-molecular level.