Yongyao Su

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.

Co3O4 based non-enzymatic glucose sensor with high sensitivity and reliable stability derived from hollow hierarchical architecture

Inspired by kinetics, the design of hollow hierarchical electrocatalysts through large-scale integration of building blocks is recognized as an effective approach to the achievement of superior electrocatalytic performance. In this work, a hollow, hierarchical Co3O4 architecture (Co3O4 HHA) was constructed using a coordinated etching and precipitation (CEP) method followed by calcination. The resulting Co3O4 HHA electrode exhibited excellent electrocatalytic activity in terms of high sensitivity (839.3 μA mM-1 cm-2) and reliable stability in glucose detection. The high sensitivity could be attributed to the large specific surface area (SSA), ample unimpeded penetration diffusion paths and high electron transfer rate originating from the unique two-dimensional (2D) sheet-like character and hollow porous architecture. The hollow hierarchical structure also affords sufficient interspace for accommodation of volume change and structural strain, resulting in enhanced stability. The results indicate that Co3O4 HHA could have potential for application in the design of non-enzymatic glucose sensors, and that the construction of hollow hierarchical architecture provides an efficient way to design highly active, stable electrocatalysts.

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.

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.