Intercalation of argon in honeycomb structures towards promising strategy for rechargeable Li-ion batteries.

High-performance rechargeable batteries are becoming very important for high-end technologies with their ever increasing application areas. Hence, improving the performance of such batteries has become the main bottleneck to transferring high-end technologies to end users. In this study, we propose an argon intercalation strategy to enhance battery performance via engineering the interlayer spacing of honeycomb structures such as graphite, a common electrode material in lithium-ion batteries (LIBs). Herein, we systematically investigated the LIB performance of graphite and hexagonal boron nitride (h-BN) when argon atoms were sent into between their layers by using first-principles density-functional-theory calculations. Our results showed enhanced lithium binding for graphite and h-BN structures when argon atoms were intercalated. The increased interlayer space doubles the gravimetric lithium capacity for graphite, while the volumetric capacity also increased by around 20% even though the volume was also increased. Theab initiomolecular dynamics simulations indicate the thermal stability of such graphite structures against any structural transformation and Li release. The nudged-elastic-band calculations showed that the migration energy barriers were drastically lowered, which promises fast charging capability for batteries containing graphite electrodes. Although a similar level of battery promise was not achieved for h-BN material, its enhanced battery capabilities by argon intercalation also support that the argon intercalation strategy can be a viable route to enhance such honeycomb battery electrodes.

Production of chlorine-containing functional group doped graphene powders using Yucel's method as anode materials for Li-ion batteries.

In this study, the one-step electrochemical preparation of chlorine doped and chlorine-oxygen containing functional group doped graphene-based powders was carried out by Yucel's method, with the resultant materials used as anode materials for lithium (Li)-ion batteries. Cl atoms and ClO x (x = 2, 3 or 4) groups, confirmed by X-ray photoelectron spectroscopy analysis, were covalently doped into the graphene powder network to increase the defect density in the graphene framework and improve the electrochemical performance of Li-ion batteries. The microscopic properties of the Cl-doped graphene powder were investigated by scanning electron microscopy and transmission electron microscopy (TEM) analyses. TEM analysis showed that the one-layer thickness of the graphene was approximately 0.33 nm. Raman spectroscopy analysis was carried out to determine the defect density of the graphene structures. The G peak obtained in the Raman spectra is related to the formation of sp2 hybridized carbons in the graphene-based powders. The 2D peak seen in the spectra shows that the synthesized graphene-based powders have optically transparent structures. In addition, the number of sp2 hybridized carbon rings was calculated to be 22, 19, and 38 for the Cl-GP1, Cl-GP2, and Cl-GOP samples, respectively. As a result of the charge/discharge tests of the electrodes as anodes in Li-ion batteries, Cl-GP2 exhibits the best electrochemical performance of 493 mA h g-1 at a charge/discharge current density of 50 mA g-1.

A Comprehensive Characterization of Particulate Matter, Trace Elements, and Gaseous Emissions of Piston-Engine Aircraft.

The gaseous and PM10 emissions of a piston-engine aircraft during ground operations at different engine states (six engine speed points and three air/fuel mixtures) representing certain flight phases were concurrently measured from the exhaust duct. PM10 emissions were sampled on a 47 mm-diameter polytetrafluoroethylene (PTFE) filter in order to be analyzed with an inductively coupled plasma mass spectrometry (ICP-MS/MS) to identify the presence and level of forty-eight elements. The most abundant element is found to be Pb (med = 4.6 × 106 ng m-3), which is 40 times the second most abundant element, Na (med = 1.1 × 105 ng m-3). The filters used for sampling exhaust gases tend to lighten with an increase in engine speed and leaning of the fuel mixture. The average of measured PM mass concentrations at all engine speeds were calculated to be 27.7 mg m-3 (full-rich) > 26.7 mg m-3 (best-power) > 24.7 mg m-3 (best-economy). The total mass of the trace elements constitutes an average of 24.1 ± 12.8% of the mass of PM. Electron microscope analyses suggest that the particles enriched by Al tend to agglomerate in a needle-shaped structure.

Optimization and performance of nitrogen-doped carbon dots as a color conversion layer for white-LED applications.

In this study, green-emitting nitrogen-doped carbon dots (N-CDots) were synthesized and incorporated into drop-cast composite films for use as color conversion layers in a white-LED configuration to generate white light. In order to resolve the red deficiency of this configuration, a commercial red phosphor was integrated into the system. Moreover, the N-CDots were also processed into polymer/N-CDot composite fibers, for which we determined the amount of N-CDots that yielded adequate white-light properties. Finally, we showed that white light with excellent properties could be generated by employing both of the fabricated N-CDot composites either as drop-cast films or composite fibers. Hence, N-CDots provide a promising alternative to inorganic phosphors that are commonly employed in white-LED configurations.

Polarized emission from CsPbBr3 nanowire embedded-electrospun PU fibers.

Interest in all-inorganic halide perovskites has been increasing dramatically due to their high quantum yield, band gap tunability, and ease of fabrication in compositional and geometric diversity. In this study, we synthesized several hundreds of nanometer long and ∼4 nm thick CsPbBr 3 nanowires (NWs). They were then integrated into electrospun polyurethane (PU) fibers to examine the polarization behavior of the composite fiber assembly. Aligned electrospun fibers containing CsPbBr 3 NWs showed a remarkable increase in the degree of polarization from 0.17-0.30. This combination of NWs and PU fibers provides a promising composite material for various applications such as optoelectronic devices and solar cells.