Yubing Wang

A fullerene-single wall carbon nanotube complex for polymer bulk heterojunction photovoltaic cells

A novel immobilized fullerene–single wall carbon nanotube (C60–SWCNT) complex was synthesized via a microwave induced functionalization approach. It has been used as a component of the photoactive layer in a bulk heterojunction photovoltaic cell. As compared to a control device with only C60, the addition of SWCNTs resulted in an improvement of both the short circuit current density JSC and the fill factor (FF). This device takes advantage of the electron accepting feature of C60 and the high electron transport capability of SWCNTs. The results indicate that C60 decorated SWCNTs are promising additives for performance enhancement of polymer photovoltaic cells.

Irreversible blocking of ion channels using functionalized single-walled carbon nanotubes

We demonstrate irreversible blocking of ion channels using single-wall carbon nanotubes (SWNTs) functionalized with 2-aminoethylmethane thiosulfonate (MTSET). In contrast, as-produced and purified SWNTs exhibit reversible blocking, indicating that the MTSET molecule attached to SWNTs chemically interacts with the cysteine groups in the ion channels. Functionalization of SWNTs with MTSET is inferred from Fourier transform infrared (FTIR) spectroscopy, which clearly shows absorptions due to??CH stretching and deformation modes, and decrease in intensity of the??COOH line due to reaction of acid functionalized SWNTs with the basic N?CH3?end of the MTSET molecule.

Microwave-assisted solid-state grafting of multi-walled carbon nanotubes on polyurethane for the synthesis of a composite with optical limiting properties

Microwave-assisted, solid-state grafting of multiwalled carbon nanotubes is presented for the synthesis of a thermal polyurethane composite. This one-step method reduced the reaction time to the order of minutes and allowed the polyurethane to be directly attached to the nanotubes, thus forming a highly solvent-dispersible composite. The composite showed excellent optical limiting characteristics at 532 as well as 1064 nm, with a threshold of 0.10 J cm−2 at 532 nm, and a higher value (1.0 J cm−2) at the latter wavelength.

Nanoscale Energetics with Carbon Nanotubes

Single wall carbon nanotubes (SWNTs) with diameters below 1 nm prepared by chemical vapor deposition (CVD), and with diameters of 1.3 nm and higher prepared by laser ablation and carbon-arc techniques, were electrochemically functionalized with hydrogen and nitro groups, and chemically derivatized with 4-nitroaniline. Hydrogen adsorption on SWNTs was carried out in the presence or absence of electrodeposited catalytic nanoparticles of magnesium. SWNTs deposited on Teflon-coated membranes by vacuum filtration and lifted off as free-standing nanopaper, were used as the electrodes for electrochemical functionalization reactions. Hydrogen uptake on the nanotubes was characterized by micro-Raman spectroscopy, thermogravimetry and thermopower measurements. Electrochemically-induced functionalization with −NO 2 groups on metallic, laser-synthesized SWNTs was clearly detected by Raman spectroscopy. Chemical functionalization was achieved on CVD-produced SWNTs by acidification to form −COOH groups followed by reaction with thionyl chloride and then with 4-nitroaniline. Photoacoustic effects that are likely to be precursors of photo-induced initiation of energetic reactions, were observed to occur at varying laser intensities for these materials in experiments using a pulsed Nd-YAG laser emitting at 532 nm.

Electrochemical Hydrogen Adsorption/Storage in Pure and Functionalized Single Wall Carbon Nanotubes

Self-assembled sheets of single wall carbon nanotubes (SWNTs) were used as the working electrode for electrochemical hydrogen adsorption/storage in a three-electrode cell in 6M aqueous KOH or HNO3 solution. Hydrogen adsorption studies on pristine SWNTs, as well as SWNTs functionalized with electrodeposited nanoparticles of magnesium (Mg) and cobalt (Co), have been performed. The adsorbed hydrogen (uncorrected for possible water uptake via nanocapillarity) was measured to be 2.5 weight percent by thermogravimetric analysis (TGA) on a Mg-functionalized sample and 3.2 weight percent by Prompt-Gamma Activation Analysis (PGAA) for a pristine sample charged for 20 hrs. Weight loss occurs in the 105 o to 125 o C temperature range for both sample types. Hydrogen in Co-functionalized SWNTs and 6M HNO3 electrolyte appears to be strongly chemisorbed as indicated by the appearance of a C-H stretching line in the Fourier-transform infrared spectrum (FTIR) and absence of a desorption peak in the TGA data in the 25 o to 600 o C temperature range. Thermopower measurements scale with the TGA data and suggest that hydrogen uptake is associated with partial charge transfer. Exsitu Raman spectroscopy shows a reproducible downshift of the SWNT tangential stretching mode consistent with charge transfer or chemisorption on electrochemical charging, and a substantial decrease under some conditions in resonance-enhanced intensity with increasing charging time. A SWNT sheet electrochemically coated with the conducting polymer polyaniline and then charged in 6M KOH shows possible hydrogen uptake of 1.5 weight % that desorbs at 70 o C.