Mengqi Yao

Remarkable electrochemical properties of novel LaNi0.5Co0.5O3/0.333Co3O4 hollow spheres with a mesoporous shell

An atomization route incorporating colloidal silica as a template was employed to synthesize LaNi0.5Co0.5O3/0.333Co3O4 (LNCO/CO) hollow spheres with a highly mesoporous shell. XRD and FESEM and HRTEM were used to characterize the crystalline phases and micro-morphology, respectively. The mesoporous shell showed a high specific surface area of 247 m2 g−1 as well as a mean pore size of about 2.53 nm as determined from N2 adsorption–desorption isotherms. The as-obtained spherical hollow spheres exhibited remarkable electrochemical performance as a battery-type electrode material with a maximum specific capacity of 498C g−1 at a current density of 2 A g−1 and ultra-long charge–discharge stability for 50 000 cycles in a three-electrode system. Additionally, a hybrid supercapacitor assembled with LNCO/CO hollow spheres as the positive electrode and N-doped mesoporous carbon as the negative electrode showed a high specific capacitance of 113.2 F g−1 at 1 A g−1 and a very high energy density of 42.8 Wh kg−1 at a power density of 424 W kg−1. The hybrid supercapacitor also exhibited a long-term cycle life of up to 30 000 cycles with a specific capacitance retention of 90.4%, and these properties meet the growing demands of long-life energy-related devices.

Iron electroplating under hydrothermal conditions to improve anticorrosion performance

ABSTRACT Abundant research activities have been devoted to metal electroplating technology and hydrothermal fields. In this work, a hydrothermal method has been applied in metal electroplating for the first time, to the authors’ knowledge. Iron coatings that are electroplated under hydrothermal conditions yield numerous enhancements in various aspects, especially in anticorrosion applications. Electrochemical tests indicate that the corrosion resistance is significantly higher in iron coatings obtained under hydrothermal conditions than in those electroplated through the traditional method. Specifically, the coating resistance of the sample that was electroplated for 20 min at a current intensity of 300 mA cm−2 and hydrothermal temperature of 120°C is up to 63.52 Ω cm2, in a 3.5 wt-% NaCl solution at 25°C, which is approximately 44% larger than the resistance of the sample electroplated traditionally.

Wire-array-applied ultrafine tungsten wire coated with Al–Mg alloy layer via electron beam evaporation

Al–Mg alloy coatings were deposited onto superfine tungsten wire substrates via electron beam deposition at electronic beam currents ranging from 80 to 120 mA. The effects of electronic beam currents and baking process on the surface characteristics of the aluminium–magnesium alloy coatings were investigated using scanning electron microscopy. Energy-dispersive X-ray was also used to investigate the composition of the coatings according to the chemical components of the source materials. X-ray diffraction results suggested that the Al–Mg alloy coatings consisted of an Al12Mg17 intermetallic compound and pure aluminium phase. Electrochemical measurements determined the corrosion protection performance of the aluminium–magnesium alloy coatings with different magnesium contents. Specimen tensile properties were related to electron beams and surface roughness. The anti-corrosion performance of the coatings was increased with magnesium content.