Yaohui Lv

Enhanced microwave absorption of flower-like FeNi@C nanocomposites by dual dielectric relaxation and multiple magnetic resonance

Flower-like FeNi@C nanocomposites self-assembled by FeNi nanosheets and flocculent carbon were synthesized by the hydrothermal method. The electromagnetic parameters of FeNi@C–paraffin composites were measured at 0.03–18 GHz. Dual dielectric relaxations were observed in the composite system due to the cooperative consequence of the FeNi–C interfaces and dielectric carbon. The strong magnetic loss is from the coexistence of natural resonance and exchange resonance. For the 2.0 mm thickness layer, an optimal reflection loss (RL) of −46.7 dB is observed at 3.17 GHz, whereas the absorbent with a thickness of 1.3 mm has an RL of −32.78 dB at 13.78 GHz. The excellent microwave absorption abilities result from the synergy of dielectric and magnetic losses and quarter-wavelength cancellation.

Ammonium sulfate regulation of morphology of Nd:Y2O3 precursor via urea precipitation method and its effect on the sintering properties of Nd:Y2O3 nanopowders

Ammonium sulfate has been widely used as a control agent in the preparation of yttrium-aluminium-garnet (YAG) transparent ceramics, however, research of its application in the preparation in transparent ceramic yttria has not been intensively studied. Neodymium–doped yttria (Nd:Y2O3) nanopowders with controlled morphology and size were synthesized via a urea precipitation method using ammonium sulfate as the additive. The effect of ammonium sulfate was intensively studied throughout the preparation process. Morphology of precursors was found to be evidently affected by the [(NH4)2SO4]/[Nd:Y2O3] ratio (measured by weight). Uniform spheres of Nd:Y2O3 precursor were obtained without the addition of ammonium sulfate. With increasing amounts of ammonium sulfate added, the scale of the Nd:Y2O3 precursors diminished which results in the aggregation of the Nd:Y2O3 precursor. Aggregates of coral like particles after precipitation and uniform well dispersed particles after calcinations were obtained as the dosage of ammonium sulfate reached 20 wt%. It was considered to be the optimum state for the preparation of highly sinterable Nd:Y2O3 nanopowders. Ammonium sulfate was proved to be a regulator that could mediate the nucleation and growth of the precursor as well as its decomposition behaviour. Results of this paper can contribute to the controllable synthesis of transparent ceramic yttria.

Facile preparation of Mn-doped CeO2 Submicrorods by composite-hydroxide-salt-mediated approach and their magnetic property

Mn-CeO2 submicrorods have been obtained from anomalous CeO2 particles though a novel composite-hydroxide-salt-mediated (CHSM) approach. This method is based on a reaction between a metallic salt and a metallic oxide in a solution of composite-hydroxide-salt eutectic at ~225 oC and normal atmosphere without using an organic dispersant or capping agent. The magnetic measurement of the Mn-CeO2 submicrorods exhibits an enhanced ferromagnetic property at room temperature with a remanence magnetization (Mr) of 1.4 × 10-3 emu.g-1 and coercivity (Hc) of 75 Oe. The UV-visible spectra reveal that the absorption peak of the CeO2 shifts from ultraviolet region to visible light region after being doped with Mn ions. The room temperature ferromagnetic properties and light absorption of the Mn-CeO2 submicrorods would have wide applications in spintroics and photocatalysis field.

Novel Ag3PO4/CeO2 p-n Hierarchical Heterojunction with Enhanced Photocatalytic Performance

The composite Ag3PO4/CeO2 photocatlyst, a novel p-n type heterojunction, has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. The X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV-visible diffuse reflectance spectra (DRS) were used to characterize the as-obtained products. The SEM and TEM image show that CeO2 particles have been successfully loaded and well distributed in the surface of Ag3PO4. The photocatalytic activities of the p-Ag3PO4/n-CeO2 heterojunctions were investigated for their efficiency on the degradation of Rhodamine B (RhB) under ultra-violet light and visible light irradiation, and the results showed that the p-Ag3PO4/n-CeO2 heterojunctions possessed remarkable photocatalytic activities. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the Ag3PO4 and the effective separation of photogenerated carriers driven by the internal electrostatic field in the junction region.

Activation of peroxymonosulfate by BiFeO3 microspheres under visible light irradiation for decomposition of organic pollutants

Visible light responsive BiFeO3 microspheres were successfully synthesized by hydrothermal method and firstly used to activate peroxymonosulfate (PMS) for oxidation and degradation of organic pollutes in water. Rhodamine B (RhB) was used as a model of organic pollutants. It was found that BiFeO3 reveals a high ability to activate PMS so that the activated PMS can generate reactive oxidative radicals for further degradation of RhB. In addition, BiFeO3 exhibited high stability and reusability in degrading organic pollutants through activation of PMS. Here, comprehensive studies on the kinetics of the reaction, PMS concentration and reaction temperature have been done and the possible mechanism was then proposed.

One-step synthesis of Ag3PO4/Ag photocatalyst with visible-light photocatalytic activity

A highly efficient photocatalyst Ag3PO4/Ag was prepared by a one-step low temperature chemical bath method. The reflectance spectra (DRS) indicated Ag3PO4/Ag had strong absorption in visible light region. The synthesized Ag3PO4/Ag photocatalyst was used as the efficient photocatalysts for the photocatalytic degradation of Rhodamine B (RhB) under visible-light illumination which showed almost complete degradation (~ 98%) of RhB dye in 90 min. The negative surface of Ag3PO4/Ag photocatalyst also promoted the degradation of a cationic dye like methylene bule (MB; 78% in 90min), while the performance against an anionic dye like methyl orange was poorer (MO; 40% in 90 min). Compared to the pure Ag3PO4 photocatalyst, the Ag3PO4/Ag photocatalyst showed the enhanced visible light photocatalytic informance. The excellent photocatalytic performance is mainly ascribed to the surface plasmon resonance of Ag nanoparticles and a large negative charge of PO43- ions.

Novel α-FeOOH Nanorods/Ag3PO4 Semiconductor Composites with Enhanced Photocatalytic Activity and Stability

The composite α-FeOOH nanorods/Ag3PO4 photocatalyst has been successfully fabricated through a facile hydrothermal process combined with a successive in situ precipitation technique. The SEM and TEM images show that Ag3PO4 particles have been successfully loaded on the surface of FeOOH nanorods. The photocatalytic activities of the α-FeOOH/Ag3PO4 composite were investigated for their efficiency on the degradation of Rhodamine B (RhB) under ultra-violet light and visible light irradiation, and the results showed that the α-FeOOH/Ag3PO4 composite possessed remarkable photocatalytic activities. The enhanced photocatalytic activity can be attributed to the strong absorption in visible light and the effective separation of photogenerated hole–electron pairs between Ag3PO4 and α-FeOOH.

2-Amino-3-nitro­pyridinium 4-hy­droxy­benzene­sulfonate

In the crystal structure of the title salt, C5H6N3O2 +·C6H5O4S−, N—H⋯O and O—H⋯O hydrogen bonds link the cations and anions. The dihedral angle between the rings of the cation and anion is 79.91 (6)°.