Hongdong Liu

Simple Synthesis of Molybdenum Disulfide/Reduced Graphene Oxide Composite Hollow Microspheres as Supercapacitor Electrode Material

MoS2/RGO composite hollow microspheres were hydrothermally synthesized by using SiO2/GO microspheres as a template, which were obtained via the sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO2 microspheres. The structure, morphology, phase, and chemical composition of MoS2/RGO hollow microspheres were systematically investigated by a series of techniques such as FE-SEM, TEM, XRD, TGA, BET, and Raman characterizations, meanwhile, their electrochemical properties were carefully evaluated by CV, GCD, and EIS measurements. It was found that MoS2/RGO hollow microspheres possessed unique porous hollow architecture with high-level hierarchy and large specific surface area up to 63.7 m2·g−1. When used as supercapacitor electrode material, MoS2/RGO hollow microspheres delivered a maximum specific capacitance of 218.1 F·g−1 at the current density of 1 A·g−1, which was much higher than that of contrastive bare MoS2 microspheres developed in the present work and most of other reported MoS2-based materials. The enhancement of supercapacitive behaviors of MoS2/RGO hollow microspheres was likely due to the improved conductivity together with their distinct structure and morphology, which not only promoted the charge transport but also facilitated the electrolyte diffusion. Moreover, MoS2/RGO hollow microsphere electrode displayed satisfactory long-term stability with 91.8% retention of the initial capacitance after 1000 charge/discharge cycles at the current density of 3 A·g−1, showing excellent application potential.

Carbon nanotubes anchored with SnO 2 nanosheets as anode for enhanced Li-ion storage

The carbon nanotubes (CNTs) anchored with SnO2 nanosheets were prepared using a hydrothermal method. The as-prepared products were characterized by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analyses, field emission scanning electron microscope and transmission electron microscope. The electrochemical performances of SnO2 nanosheets/CNTs composite were measured by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the SnO2 nanosheets/CNTs composite maintains high lithium storage capacity and good cycling stability. The designed structure plays key role in improving electrochemical performance. The CNTs anchored with SnO2 nanosheets will be an ideal candidate of anode material for lithium ion batteries.

Graphene as a high-capacity anode material for lithium ion batteries

Graphene was produced via a soft chemistry synthetic route for lithium ion battery applications. The sample was characterized by X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron microscopy and transmission electron microscopy, respectively. The electrochemical performances of graphene as anode material were measured by cyclic voltammetry and galvanostatic charge/discharge cycling. The experimental results showed that the graphene possessed a thin wrinkled paper-like morphology and large specific surface area (342 m2·g−1). The first reversible specific capacity of the graphene was as high as 905 mA·h·g−1 at a current density of 100 mA·g−1. Even at a high current density of 1000 or 2000 mA·g−1, the graphene maintained good cycling stability, indicating that it is a promising anode material for high-performance lithium ion batteries.

Nanostructured MnO2 anode materials for advanced lithium ion batteries

Owing to the high reversible capacity, low-cost, natural abundance and environmental friendliness, manganese dioxide (MnO2) is recognized as one of the most appropriate and promising anode materials. In this work, nanostructured MnO2 anode materials have been achieved via a hydrothermal method. The crystal structure, morphology and specific surface area of as-prepared MnO2 are characterized by XRD, SEM and BET techniques. As anode materials for lithium-ion batteries, MnO2 samples show high initial discharge capacity and relatively excellent cyclic performance. The electrochemical performance of MnO2 samples is related to crystal structure and surface morphology. Monoclinic structure, it is similar to graphene, which is more convenient for the fast ionic transportation into the bulk of the electrode materials. And porous structure, which can accommodate volume expansion, shorten the electron and lithium ion diffusion pathway and provide a large number of electrochemical reactive sites for lithium ion insertion and extraction during cycling.

Facile one-pot synthesis of self-assembled 3-D flower-like SnO2 architectures and their electrochemical properties

In this work, self-assembled 3-D flower-like SnO2 architectures have been successfully synthesized by one-pot hydrothermal method. The structure and morphology of flower-like SnO2 architectures were investigated by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. The electrochemical performance of self-assembled 3-D flower-like SnO2 architectures was measured by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. As anode materials in lithium ion batteries, the results show that the obtained SnO2 architectures exhibit high lithium storage.

One-pot synthesis of cubic PtPdCu nanocages with enhanced electrocatalytic activity for reduction of H2O2

Despite the high electrocatalytic activity of Pt, pure Pt electrocatalysts always suffer from high cost and poor poison resistance. In this work, a cubic PtPdCu nanocage (NC) trimetallic electrocatalyst was synthesized using cuprous oxide as a sacrificial template. Being employed as a H2O2 detection electrode, PtPdCu NCs exhibit higher sensitivity (562.83 μA mM−1 cm−2) than that of PdCu NCs (210.19 μA mM−1 cm−2), PtCu NCs (411.34 μA mM−1 cm−2) and commercial Pt black (16.94 μA mM−1 cm−2). Furthermore, a PtPdCu NCs electrode presents a working potential as low as 0.05 V. The excellent electrocatalytic activity can be attributed to the suitable hollow porous structure and synergistic electrocatalysis effect between Pt, Pd and Cu. It is believed that the trimetallic PtPdCu NCs electrocatalyst has potential applications in the design of H2O2 detection electrodes.

Effect of Sputtering Current on the Comprehensive Properties of (Ti,Al)N Coating and High-Speed Steel Substrate

To improve the practical property of (Ti,Al)N coating on a high-speed steel (HSS) substrate, a series of sputtering currents were used to obtain several (Ti,Al)N coatings using a magnetron sputtering equipment. The phase structure, morphology, and components of (Ti,Al)N coatings were characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy, respectively. The performance of (Ti,Al)N coatings, adhesion, hardness, and wear resistance was tested using a scratch tester, micro/nanohardness tester, and tribometer, respectively. Based on the structure–property relationships of (Ti,Al)N coatings, the results show that both the Al content and deposition temperature of (Ti,Al)N coatings increased with sputtering current. A high Al content helped to improve the performance of (Ti,Al)N coatings. However, the HSS substrate was softened during the high sputtering current treatment. Therefore, the optimum sputtering current was determined as 2.5 A that effectively increased the hardness and wear resistance of (Ti,Al)N coating.

Template-free synthesis of Sb-doped SnO2 microspheres and their electrochemical properties

Sb-doped tin oxide (ATO) microspheres prepared by a hydrothermal method as anode materials for lithium-ion batteries. The samples were characterized by XRD, BET and SEM. The electrochemical properties of ATO microspheres were examined by charge/discharge measurements. The results show that ATO microspheres exhibit much higher reversible capacity and better cycling performance.

Fabrication of high-quality copper nanowires flexible transparent conductive electrodes with enhanced mechanical and chemical stability

Copper nanowires (Cu NWs) become a potential functional material in future optoelectronic devices owing to their high optical transmittance, super electrical conductivity, and good flexibility as well as low cost. However, the drawbacks of Cu NWs with large contact resistance and poor stability make them far from the practical implementations. Herein we report a robust method to fabricate high-quality Cu NWs transparent conductive electrodes (TCEs) with enhanced mechanical and chemical stability at room temperature. Firstly, we used a sodium borohydride (NaBH4) treatment to remove the organics and oxides on surface of Cu NWs and thus greatly improved the conductivity of Cu NWs TCEs. Subsequently, followed by decorating a dense hydrophobic dodecanethiol (DT) protective layer, the formed Cu NWs TCEs showed superior mechanical and chemical stability compared to the raw ones. The optimized Cu NWs TCEs exhibit a sheet resistance of ∼38 Ω/sq at an optical transmittance of 83% (550 nm). Unlike the bare Cu NWs, the DT-decorated Cu NWs showed good stability under humid conditions at (85% RH) at 85 °C for 12 h. Moreover, the DT-decorated Cu NW TCEs were tested as transparent heaters, showing the fast response time and high saturation temperature under a low DC voltage. Our studies demonstrate that the proper post treatments for Cu NWs TCEs would make them more competitive in application of next-generation electronic and optoelectronic devices.

Deposition Process and Properties of Electroless Ni-P-Al 2 O 3 Composite Coatings on Magnesium Alloy

To improve the corrosion resistance and wear resistance of electroless nickel-phosphorus (Ni-P) coating on magnesium (Mg) alloy. Ni-P-Al2O3 coatings were produced on Mg alloy from a composite plating bath. The optimum Al2O3 concentration was determined by the properties of plating bath and coatings. Morphology growth evolution of Ni-P-Al2O3 composite coatings at different times was observed by using a scanning electronic microscope (SEM). The results show that nano-Al2O3 particles may slow down the replacement reaction of Mg and Ni2+ in the early stage of the deposition process, but it has almost no effect on the rate of Ni-P auto-catalytic reduction process. The anti-corrosion and micro-hardness tests of coatings reveal that the Ni-P-Al2O3 composite coatings exhibit better performance compared with Ni-P coating owing to more appropriate crystal plane spacing and grain size of Ni-P-Al2O3 coatings. Thermal shock test indicates that the Al2O3 particles have no effect on the adhesion of coatings. In addition, the service life of composite plating bath is 4.2 metal turnover, suggesting it has potential application in the field of magnesium alloy.