This paper reports the successful preparation of Mg-doped VO2 nanoparticles via hydrothermal synthesis. The metal-insulator transition temperature (T(c)) decreased by approximately 2 K per at% Mg. The Tc decreased to 54 °C with 7.0 at% dopant. The composite foils made from Mg-doped VO2 particles displayed excellent visible transmittance (up to 54.2%) and solar modulation ability (up to 10.6%). In addition, the absorption edge blue-shifted from 490 nm to 440 nm at a Mg content of 3.8 at%, representing a widened optical band gap from 2.0 eV for pure VO2 to 2.4 eV at 3.8 at% doping. As a result, the colour of the Mg-doped films was modified to increase their brightness and lighten the yellow colour over that of the undoped-VO2 film. A first principle calculation was conducted to understand how dopants affect the optical, Mott phase transition and structural properties of VO2.

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Rechargeable sodium‐ion batteries (SIBs) are considered attractive alternatives to lithium‐ion batteries for next‐generation sustainable and large‐scale electrochemical energy storage. Organic sodium‐ion batteries (OSIBs) using environmentally benign organic materials as electrodes, which demonstrate high energy/power density and good structural designability, have recently attracted great attention. Nevertheless, the practical applications and popularization of OSIBs are generally restricted by the intrinsic disadvantages related to organic electrodes, such as their low conductivity, poor stability, and high solubility in electrolytes. Here, the latest research progress with regard to electrode materials of OSIBs, ranging from small molecules to organic polymers, is systematically reviewed, with the main focus on the molecular structure design/modification, the electrochemical behavior, and the corresponding charge‐storage mechanism. Particularly, the challenges faced by OSIBs and the effective design strategies are comprehensively summarized from three aspects: function‐oriented molecular design, micromorphology regulation, and construction of organic–inorganic composites. Finally, the perspectives and opportunities in the research of organic electrode materials are discussed.

Bimetallic nanoparticles (NPs) usually exhibit some novel properties due to the synergistic effects of the two distinct metals, which is expected to play an important role in the field of gas sensing. PdPt bimetal NPs with Pd-rich shell and Pt-rich core were successfully synthesized and used to modify SnO 2 nanosheets. The 1P-PdPt/SnO 2 -A sensor obtained by self-assemblies of PdPt NPs exhibited temperature-dependent dual selectivity to CO at 100 °C and CH 4 at 320 °C. Furthermore, the sensor possessed good long term stability and antihumidity interference. The activation energy of adsorption for CO and CH 4 were estimated by the temperature-dependent response process modeled using Langmuir adsorption kinetics, which proved that the lower activation energy of adsorption corresponded to better sensing performance. The gas-sensing mechanism based on the diffusion depth of the tested gas in the sensing layer was discussed. The dramatically improved sensing performance could be ascribed to the high catalytic activity of PdPt bimetal, the electron sensitization of PdO, and Schottky barrier-type junctions at the interface between SnO 2 and PdPt NPs. Our present results demonstrate that bimetal NPs with special structure and components can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.

ABSTRACT:A combined density functional theory and Green's function procedure is used to calculate the electrical characteristics of a group of alkanethiols representing possible experimental settings. It is found that the current running through the molecule is the sum of the contributions from all molecular orbitals each presenting a barrier to electron transport equal to their energy difference from the Fermi level of the contacts. For the alkanethiols the location of these intrinsic barriers are at 0.78 eV (highest occupied molecular orbital [HOMO] and HOMO-1), 1.99 eV (HOMO-2 and HOMO-3), 2.07 eV (LUMO and LUMOϩ1), and 2.67 eV (HOMO-4). However, barriers obtained through fittings to known models do not bear any physical meaning at the molecular level, as they are sort of exponential average of the intrinsic barriers. We have also found that the exponential dependence of the current with the length of the alkane is practically independent of the contact nature, perhaps due to the large resistance of the alkanes.