Search

Abstract An intricate sea-urchin-like hexagonal WO 3 nanostructure was synthesized by a facile hydrothermal approach. Sensing properties of the as-fabricated sensor exhibited surpassing response and selectivity for NO 2 in comparison of H 2 after corroborating the composition, phase-purity and surface morphology using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Formation of the urchin-like structure was ascribed to the capping effects of potassium sulfate that prompts the anisotropic growth of WO 3 , leading to hierarchical complex with a large surface-volume ratio. In particular, first-principle calculation had provided a new perspective for us to delve into the sensing process of H 2 and NO 2 from an atomic level. It was found that the sensing properties mainly arose from the tuning of electronic structure and electrons transfer between the adsorbed gas and the sensitized surface along with the charge relocation between them. Finally, a plausible mechanism was proposed as theoretical guidance for achieving high-performance sensors experimentally and supposedly. [ABSTRACT FROM AUTHOR]

We report on the synthesis of pristine and Cu-doped SnO 2 spheres using a facile hydrothermal method and investigate their microstructures and gas-sensing response. We focus on how Cu doping can have an impact on gas-sensing behavior of SnO 2 -based sensors toward H 2 S. We find that Cu doping can enhance significantly the gas response of SnO 2 toward H 2 S, the origin of which can be clarified with a proposed adsorption model. First-principles calculations reveal that adsorption energy of H 2 S on Cu-doped surface is lower than that on undoped one and the interaction between adsorbed H 2 S and Cu-doped surface is stronger than that between adsorbed H 2 S and pure surface, which consequently improves gas-sensing performances of SnO 2 toward H 2 S. Such a combined experimental and calculational study offers an explanation on how Cu doping affects gas-sensing performances of SnO 2 . [ABSTRACT FROM AUTHOR]

The selection of electrode materials and the optimization of electrode configurations are two effective approaches to achieve high-performance energy storage. As a representative ternary metal oxide, CoMoO 4 has been directly grown on the carbon cloth via a facile hydrothermal method and subsequent calcination, forming a binder-free electrode. Further measurements reveal that this electrode is composed of CoMoO 4 nanosheets assembled 3D-framworks (NAFs) and thereby shows a superb electrochemical property in KOH solution. It is worth mentioning that the specific capacitance reaches as high as 1234 F/g at the current density of 1 A/g, which exceeds most of CoMoO 4 and CoMoO 4 -based composites reported so far. Meanwhile, when the current density increases to 10 A/g, a considerable specific capacitance of 446 F/g is still obtained and can maintain nearly unchanged after 5000 cycles. [ABSTRACT FROM AUTHOR]

In the work, four types of typical morphologies of differently dimensional pure V 2 O 5 nanostructures including nanoflowers, nanoballs, nanowires and nanorods were synthesized through a simple hydrothermal method. The morphology of the product depends on the types of solvent and acid. Hierarchical nanoflowers and zero-dimensional (0D) nanoballs of V 2 O 5 nanocrystals were obtained when using C 2 H 5 OH as solvent. One dimensional (1D) nanowires and nanorods were obtained if H 2 O was used to participate in the reaction. The morphology and structure of the samples were characterized by XRD and SEM, respectively. The electrochemical behaviors of nanoflowers, nanoballs, nanowires and nanorods as electrodes in a supercapacitor device were tested using cyclic voltammetry (CV) curves and galvanostatic charge–discharge (GCD) curves. The electrochemical test results indicate that the rod-like structure leads to a significant improvement of storage capacity, electrochemical kinetics and rate capability. And 1D V 2 O 5 nanorods show the largest specific capacitance of 235 F g −1 at the current density of 1 A g −1 when used as supercapacitor electrode in 1 mol/L Na 2 SO 4 electrolyte. It turns out that 1D V 2 O 5 nanorod is an ideal material compared with other morphologies for supercapacitor electrode. [ABSTRACT FROM AUTHOR]