Yi-Jin Wang

Preparation and characterization of Ag2CrO4/few layer boron nitride hybrids for visible-light-driven photocatalysis

Nanosized Ag2CrO4/few layer boron nitride composites were prepared via in situ precipitation method. The crystal structure, morphology, optical properties, and charge carrier behavior were investigated by X-ray diffraction, transmission electrical microscopy, UV-vis diffuse reflectance spectroscopy, and electrochemical impedance spectroscopy, respectively. The photocatalytic activities of the as-prepared hybrids were discussed by degradation of rhodamine B under visible-light irradiation. Experimental results showed that the average size of pure Ag2CrO4 particles was about 20xa0nm. Moreover, the degradation efficiency of the as-prepared hybrids was first increased and then decreased with increasing the usage amount of few layer boron nitride nanosheets. When it was 10xa0wt%, in 120xa0min, the degradation efficiency of the as-prepared hybrids had reached the maximum of 96.7%. It was much higher than 75% of pure Ag2CrO4 nanoparticles. After 3xa0cycles of the degradation, the efficiency of the as-prepared composites was decreased from 96.7 to 91.8%. Trapping experiment results revealed that holes played a major role during the photocatalysis process. In addition, electrochemical impedance spectroscopy results indicated that few layer boron nitride nanosheets could enhance the separation and transfer of photogenerated electrons and holes.

The effect of structural phase transition on the magnetic properties of BiFeO3 thin films

Bi1-xErxFeO3 (xxa0=xa00, 0.05, 0.1 and 0.15 respectively) thin films were prepared by the ethylene glycol based sol–gel spin-coating method on cleaned Si (100) substrates. Effects of Er concentration on the phase formation, surface morphology and magnetic properties of BFO films were systematically investigated. Moreover, the oxidation state of Fe ion was studied by X-ray photoemission spectroscopy. X-ray diffraction and Raman spectroscopy indicated the substitutions of Er into the Bi site and a phase transition from rhombohedral to orthorhombic with Er-substitution. Scanning electron microscope and transmission electron microscope used to analyze the morphologies and microstructures of the thin films. In comparison with the other thin films studied here, the Bi0.9Er0.1FeO3 thin film exhibited the largest magnetization and a smooth morphology. The possible reasons for the enhancement of the magnetization of these films were discussed.

Boron Nitride Nanoparticles with High Specific Surface Area: Preparation by a Calcination Method and Application in Epoxy Resin

Boron nitride nanoparticles were prepared in a muffle furnace at 1000u2009°C by using commercial available boron nitride flakes and sodium chloride as raw materials. The structure, functional groups, morphology and specific surface area of the as-prepared samples were characterized by X-ray diffracmeter, fourier-transform infrared spectrometer, transmission electron microscope and accelerated surface area/porosimetry system, respectively. In order to evaluate the properties of the as-prepared products, they were mixed with epoxy resin to fabricate polymer-based composites. Experimental results showed that the average size and specific surface area of the as-prepared nanoparticles were about 20xa0nm and 895.7xa0m2/g. Moreover, the as-prepared nanoparticles could improve the tensile strength and elongation at break of the epoxy matrix. Both of them were first increased and then decreased with increasing the usage amount of the as-prepared nanoparticles. When the usage amount of the boron nitride nanoparticles was 0.4xa0wt%, the tensile strength and elongation at break of the composites reached to 71.4xa0MPa and 22.1%, which were the maximum values of the composites, respectivley. They were increased by 137 and 146% more than those of pure epoxy resin. In addition, the as-prepared fillers could accelerate the solidification of the matrix.

Preparation and Characterization of Nanosized Bi-Doped SnO2/Reduced Graphene Oxide 3D Hybrids for Visible-Light-Driven Photocatalysis

The nanosized Bi-doped SnO2/reduced graphene oxide 3D hybrids have been synthesized via one-step hydrothermal method. The structures, morphologies, photocatalytic activities of the as-prepared samples were discussed, respectively. The formation mechanism of the as-prepared hybrids was also proposed. Experimental results indicated that the usage amount of Bi2Sn2O7 obviously affected the photocatalytic performance of the as-prepared products. When it was 450 mg, the as-prepared sample possessed the band gap energy of 1.9 eV and the photocatalytic efficiency of 90% in 210 min for degradation of rhodamine B solution. In addition, triethylene tetramine and the as-prepared carbon hydrogel could act as reductant to synergistically reduce Bi2Sn2O7 into Bi-doped SnO2 particles during the formation of the hybrids.

Designing visible-light-driven direct Z-scheme Ag 2 WO 4 /WS 2 heterojunction to enhance photocatalytic activity

The direct Z-scheme Ag2WO4/WS2 photocatalysts had been fabricated by using a deposition method. Experimental results indicated that WS2 nanosheets could improve the photocatalytic activity, light absorption and recyclability of Ag2WO4 under the visible light irradiation. The degradation efficiency of the as-obtained Ag2WO4/WS2 hybrids for rhodamine B displayed first increasing and then decreasing with increasing the usage of WS2 nanosheets. When the usage of WS2 was 15xa0wt%, in 120xa0min, it reached the maximum of 97.8%, which was higher than 17.8% of pure Ag2WO4. Moreover, after three cycles of the degradation, the as-prepared hybrids still possessed 94.4% of the degradation efficiency, which increased by 1211.1% compared with pure Ag2WO4. Moreover, superoxide and hydroxyl radicals played major role during the process of photocatalytic degradation. The enhanced photocatalytic activity could be ascribed to the formation of direct Z-scheme photocatalytic system between Ag2WO4 and WS2.

Isothermal Crystallization Properties of Polyamide 6 / Hexagonal Boron Nitride Nanocomposites

ABSTRACT Hexagonal boron nitride was adopted as a heterogeneous nucleation agent to fabricate polyamide 6 based nanocomposite films via a solution casting method. Isothermal crystallization behaviors of the as-prepared films were measured by using differential scanning calorimetry. Results showed that both the crystallization temperature and fillers loading greatly affected the crystallization process of the as-prepared samples. The crystallization nucleation and growth mechanism did not change during the initial stage of crystallization. The halftime of crystallization gradually increased with increasing crystallization temperature. Moreover, it decreased first and then increased with increasing the fillers loading at low crystallization temperature, while it decreased gradually at high crystallization temperature. Furthermore, the crystallization activation energy of the as-prepared samples gradually decreased with increasing fillers loading.