Narrow Results

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high quality and quantity carbon nanotubes. The reaction temperature was optimized to produce high yield and purity of the carbon nanotubes. The reaction temperatures were varied from 500–850°C. The result shows that carbon nanotubes were observed from 600°C to 850°C with maximum numbers and high purity at 850°C. The diameter range of CNTs varied from 2 to 55 nm. The results of the present investigation suggest that the observed changes in catalytic activity and selectivity accompanying an increase in temperature are probably due to major alterations in the distribution of atoms at the metal/gas interface. Thermodynamically, higher temperatures favor the surface decomposition of hydrocarbon rather than the hydrogenation reactions.

Cadmium (Cd${}^{2+}$) is one of the toxic heavy metals that is frequently used in many industrial products. The wastewater from these industries and their products contains residual cadmium that are difficult to be removed economically from the effluent. Carbon nanotubes (CNTs) were synthesized in several batches and tested for their removal efficacy with regards to cadmium removal from synthetic wastewater. Fixed catalyst chemical vapor deposition (FCCVD) reactor system was fabricated in the laboratory for the synthesis of CNTs on the powdered activated carbons (PACs). The PACs were impregnated with Fe${}^{3+}$ catalysts, and growth parameters such as the reaction time, gas flow rates and reaction temperature were optimized. The sorption capacity of the raw CNT–PAC was not satisfactory until the sorbents were functionalized which eventually led to high adsorption capacities. The surface properties of CNT–PAC were modified by oxidative functionalization using two different methods: sonication with KMnO₄ and refluxing with HNO₃ at 140${}^{\circ }$C. KMnO₄-treated CNT–PAC exhibited the highest sorption capacity for cadmium uptake which increased from 4.77mg/g (untreated CNT–PAC) to 11.16mg/g; resulting in Cd${}^{2+}$ removal efficiency from 38.87% to 98.35%.

Use of Electronic skin (E-skin) has attracted significant attention, as it has broad application prospects in medical care, wearable electronic equipment, and body monitoring — particularly with respect to human motion detection. In this work, we developed a flexible, tensile strain sensor based on the dry printing method. A conductive layer, with a miniaturized network structure, was obtained by: (1) packing the grooves of a grid-like silicon template with a conductive powder composed of carbon nanotubes (CNTs) and silicon dioxide (SiO${}_2)$ nanoparticles; (2) infiltrating liquid polydimethylsiloxane (PDMS) into the powder voids using a coated, flexible PDMS substrate cover; (3) transferring the solidified, patterned conductive powder onto the flexible substrate by peeling the PDMS substrate cover off the template; (4) fabricating metal electrodes at both ends of the conductive layer and (5) encapsulating the strain sensor with liquid PDMS. After manufacture, the strain sensor was tested using the tensile test. Results from the tensile test demonstrate that the sensor has excellent electrical conductivity, including super high-sensitivity $(\mathrm{\text{GF}}>1450)$, a large strain range (up to 35%), and good transparency; as ultraviolet (UV) spectrum analysis shows that the transmittance can reach $>60$%. Thus, the sensor is potentially applicable to numerous sub-specialties that require specialized electronics.

In this work, a sandwich structure electrode was prepared by a simple vacuum filtration and rolling process. The SEM showed that the active materials were uniformly embedded in the pores of the three-dimensional conductive network of the carbon nanotube (CNTs) conductive paper. The contact interface area of active material and the conductive network significantly increased and the interface resistance was greatly reduced. The porous anode can accommodate the volume expansion of the silicon and effectively alleviated pressed during cycle. The electrode also exhibited good stability in cycles. Electrochemical tests showed that the first discharge specific capacity of the sandwich electrode reached 2330mAh/g with a coulombic efficiency of 86%. After 500 cycles, the specific capacity was still maintained at 1512mAh/g. At a large current density of 2A/g, the specific capacity hold was 840mAh/g compared with the copper foil electrode of 100mAh/g.