MnO2/MnO cathode material with superior Zn2+ storage performance is prepared through a simple physical mixing method. The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity (364.2 mA·h/g at 0.2C), good cycle performance (170.4 mA·h/g after 100 cycles) and excellent rate performance (205.7 mA·h/g at 2C). Analysis of cyclic voltammetry (CV) data at various scan rates shows that both diffusion- controlled insertion behavior and surface capacitive behavior contribute to the Zn2+ storage performance of MnO2/MnO cathodes. And the capacitive behavior contributes more at high discharge rates, due to the short paths of ion diffusion and the rapid transfer of electrons. 相似文献
The emission characteristics of vehicles fueled by hydrogen-enriched syngas were investigated under the no-load condition. Syngas was produced using a fixed-bed gasification system. A Jetta car was modified and used for emission experiments with engine speed between 800 and 4800 rpm. Syngas compositions and emissions were analyzed using gas chromatography and a SPX-Tecnotest 488 exhaust gas analyzer, respectively. The results showed that syngas composition had significant effect on HC and NOx emission and air ratio (λ) was the key factor affecting CO emission. HC and NOx emissions increased significantly from 6 to 16 ppm and 139–832 ppm, respectively, when engine speed increased from 800 to 4800 rpm. CO emission did not significantly increase (lower than 0.5%) at engine speed less than 3200 rpm; at higher than 4800 rpm engine speed, CO emission increased rapidly (up to 2.7%). 相似文献
ZnO nanorod arrays (NRAs) grown on the Zn foil substrate in the dual alkaline solution by hydrothermal method were first successfully utilized for photoelectrochemical (PEC) water splitting. ZnO NRAs were sufficiently covered on the Zn foil substrate via the reasonable match of the pH value, reaction temperature and reaction time through intensive experimental works. To enhance PEC performance, ZnS was coated on the surfaces of ZnO NRAs by ion exchange. The morphological, structural, optical and PEC characteristics of as-grown ZnO NRAs and ZnO/ZnS heterostructures were investigated. Compared with the pristine smooth and hexagonal ZnO NRAs, the surfaces of ZnO/ZnS heterostructures become rough and rounded in shape. Through the sulfidation treatment, some ZnO/ZnS heterostructures with a diameter of no more than 60 nm break and fade away, leading to a decrease in number density of ZnO/ZnS heterostructures. The texture coefficients of (002) diffraction peaks of ZnO decrease from 2.32 to 2.158. ZnO/ZnS heterostructures exhibit efficient separation rate of electron-hole pairs and enhanced visible light absorption, and thus have higher photocurrent density and photoconversion efficiency. In the polysulfide electrolyte solution, ZnO/ZnS heterostructures show good stability. 相似文献
We focus on the quantitative and local topological properties of range images. We consider the spaces Mm of m × m high-contrast patches of range images for m=?3, 5, 7, 9, 11. Using computational topological tools to analyze range image patches, we detect that M3 (M9, M11) has core subsets with the topology of a circle, M3, M5, M7, M9 and that M11 have some subspaces with the topology of a Klein bottle. We also discover that the largest subspace with the Klein bottle’s topology decreases as the measurements of patches increase, which generalizes the results in the paper of H. Adams and G. Carlsson, and demonstrates properties among optical images and range image patches, which are more similar than those established by Lee et al.
Journal of Materials Science - The design of the hierarchical structure and geometry of nanomaterials at the molecular and macroscopic level are crucial to determine their properties and... 相似文献
As a novel co-catalyst, Ti3C2 MXene has an excellent prospect in the field of photocatalysis. Herein, the 2D/3D Ti3C2 MXene@CdS nanoflower (Ti3C2@CdS) composite was successfully synthesized by a hydrothermal method. The combination of 2D Ti3C2 MXene and 3D CdS nanoflowers can promote carrier transfer and separation, which can improve the performance of CdS. Compared to pure CdS nanoflowers, Ti3C2@CdS composite presents lower photoluminescence intensity, longer fluorescence lifetime, higher photocurrent density and smaller electrochemical impedance. The Ti3C2@CdS composite with 15 wt% Ti3C2 adding amount presents high photocatalytic hydrogen evolution activity (88.162 μmol g?1 h?1), 91.57 times of pure CdS. The improved photocatalytic activity of Ti3C2@CdS composite is ascribed to the addition of lamellar Ti3C2 MXene, which improves the electrical conductivity of the photocatalytic system and effectively accelerates the excited electrons transfer from CdS to Ti3C2 MXene. 相似文献
The phase pure ZnGa2O4 and ZnGa2O4 doped with Cr ions nanoparticles were successfully synthesized by the hydrothermal method, whose average particle sizes are about 10 nm, and the doping of Cr ions can slightly increase the particle sizes. The doping Cr ions can evenly distribute in the samples by the hydrothermal method. The infrared characteristic peaks of the products are in the range of 400–1000 cm?1. Blue emission is observed in phase pure ZnGa2O4, while NIR emissions are observed in the ZnGa2O4 products doped with Cr ions. ZnGa2O4:Cr nanoparticles have great application prospects in the field of biomedical imaging.
The Journal of Supercomputing - Many interconnection networks in large-scale parallel computing have hierarchical and recursive structures. The presence of vertex failures may disconnect the entire... 相似文献