Simultaneous manipulation of polarization relaxation and conductivity toward self-repairing reduced graphene oxide based ternary hybrids for efficient electromagnetic wave absorption.

In consideration of the growing electromagnetic wave (EMW) pollution and interference, it is of crucial and imperative significance to develop high-efficiency EMW absorption materials. Herein, hierarchical hybrid network of MoS2@poly (3, 4-ethylenedioxythiophene) (PEDOT)/reduced graphene oxide (rGO) were successfully constructed and fabricated through the combination of oxidative polymerization and microwave-irradiated thermal reduction. The original defects in graphene oxide (GO) could be in situ repaired by introducing carbon source, and the rational regulation of polarization relaxation and conductivity of composites could be achieved. Profiting from the good impedance matching, ameliorated conductivity and enhanced dipole polarization as well as interfacial polarization by introducing GO/defect-recovered rGO and conductive PEDOT, both the MoS2@PEDOT/GO and MoS2@PEDOT/rGO composites exhibited outstanding EMW absorption performances. In details, the minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) of MoS2@PEDOT/GO can reach -48.65 dB at 4.5 mm, and 6.48 GHz (11.52-18 GHz) at 2.2 mm, respectively. And the EAB of MoS2@PEDOT/rGO can reach 7.04 GHz (10.8-17.84 GHz) with an optimized RLmin of -32.41 dB at 2.1 mm under 20 wt% filler loading. Therefore, these composites can be regarded as competitive candidates for lightweight and high-efficient EMW absorbers.

Mechanistic insights into morphological and chemical changes during benzenesulfonic acid pretreatment and simultaneous saccharification and fermentation process for ethanol production.

The anatomical and histochemical characterization of pretreated substrates is essential for the further valorization of biomass during the biorefinery process. In this work, the benzenesulfonic acid (BA)-treated substrates were employed for simultaneous saccharification and fermentation (SSF) of ethanol for the first time. An ethanol yield of 50.36% was attained at 10% solids loading and 47.45 g/L of ethanol accumulated at 30 % solids loading. The dramatic improvements could result from the deconstruction of cell walls, which were evidenced by fluorescence microscope and confocal Raman microscopy spectra. Additionally, for a thorough comprehension of the inherent chemistry of lignin during the BA pretreatment, the changes in lignin structure features were identified for the first time by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). In summary, this study tried to probe the possibility of BA-treated Miscanthus for the SSF process and unveiled the mechanism of the efficient BA pretreatment.

Temperature effect on vibrational properties of crystalline Dibenz[a,h]anthracene.

Vibrational properties associated with the intra- and intermolecular bonding of the crystalline Dibenz[a,h]anthracene at low temperatures are investigated by Raman scattering. A complete characterization of phonon spectra is given for this material. In the 120-150 K temperature region, several lattice modes show abrupt changes of splitting and the discontinuities in the temperature shift, but no emergence of new modes. Moreover, the intensity ratio of I68/38 is greater than 1 below 130 K. Meanwhile, the aromatic C-C stretching modes exhibit anomalous behaviors in frequencies, widths, and intensities at about 130 K. These spectroscopic results demonstrate a disorder-order transition occurred at about 130 K. However, the modes, corresponding to C-H out-of-plane bending, C-H in-plane bending, and/or C-H rocking, have no significant change in the whole temperature range. It indicates that the transition mainly results from the change of the tilt angle between the molecules. Our work is of great significance to understand the internal vibrational properties of Dibenz[a,h]anthracene, and it also provides considerable supports for the further study of this material.

Constructing a Green Light Photodetector on Inorganic/Organic Semiconductor Homogeneous Hybrid Nanowire Arrays with Remarkably Enhanced Photoelectric Response.

We demonstrate that a novel photodetector is constructed by CdS/poly( p-phenylene vinylene) (PPV) homogeneous hybrid nanowire arrays via a simple template-assisted electrochemical codeposition approach. Owing to the well-matched energy levels between CdS and PPV, the recombination of photogenerated electrons and holes in CdS/PPV hybrid nanowire arrays is greatly inhibited. It is found that the homogeneous hybrid nanowire arrays exhibit remarkably enhanced photoelectric response and the ON/OFF ratio by 17 times compared to the individual CdS component. More importantly, the CdS/PPV hybrid nanowire arrays are observed with significant spectral selectivity especially for green light under 545 nm. In addition, a straight linear relationship is obtained between the ON/OFF ratios and the illumination intensities, implying that the quantitative detection of illumination intensity can be achieved. The new as-prepared homogeneous hybrid organic/inorganic semiconductor nanowire arrays have a bright prospect for applications in high-sensitivity and high-speed green photodetectors.

Synthesis of Chromium Carbide Nanopowders by Microwave Heating and Their Composition and Microstructure Change under Gamma Ray Irradiation.

Chromium carbide nanopowders were synthesized by mechanical alloying-assisted microwave heating. The effect of gamma irradiation on phase composition and microstructure of chromium carbide nanopowders synthesized by the microwave heating method was analyzed. The samples were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The results showed that well-dispersed chromium carbide nanopowders can be synthesized by maintaining the temperature at 1000 °C for 1 h. Gamma ray irradiation had an important effect on the microstructure of chromium carbide nanopowders. The interplanar spacings of chromium carbide (110) crystal faces before and after gamma ray irradiation were 0.3725 nm and 0.3824 nm, respectively. The crystal structure of chromium carbide was changed by gamma ray irradiation. Gamma ray irradiation can also increase the binding energy of chromium carbide, which is beneficial to improve the thermal stability and mechanical properties of chromium carbide at high temperature.