Qiangchun Liu

Monodispersed hierarchical γ-AlOOH/Fe(OH)3 micro/nanoflowers for efficient removal of heavy metal ions from water

Many nanomaterials have been reported for the removal of toxic inorganic metal ions. Some conventional micro- or nano-structured adsorbents are subject to serious aggregation. Here, well-dispersed, Fe(OH)3 colloid nanoparticles have been effectively deposited onto the surfaces of hierarchical γ-AlOOH nanostructures to form γ-AlOOH/Fe(OH)3 with hierarchical structures via an electrostatic attraction without forming large aggregates. The monodispersed γ-AlOOH/Fe(OH)3 with hierarchical structures have high specific surface areas and large pore volumes, which are used as adsorbents to remove anion species of As(V) and Cr(VI) from aqueous solution. The maximum capacities of the monodispersed γ-AlOOH/Fe(OH)3 with hierarchical structures for As(V) and Cr(VI) in this study are determined at 43.8 mg g−1 and 13.1 mg g−1, respectively, which are higher than those of the other metal oxide nanostructures reported to date. In addition, the adsorption rates of As(V) and Cr(VI) onto the monodispersed γ-AlOOH/Fe(OH)3 with hierarchical structures are rather fast. The γ-AlOOH/Fe(OH)3 hierarchical micro/nanoflower structures show high adsorption capacity for removing the anion species of As(V) and Cr(VI), demonstrating a promising potential in environmental remediation.

Structure and band gap engineering of Fe-doped SrSnO3 epitaxial films

(SSFO) films were epitaxially grown on MgO substrates by pulsed-laser deposition. X-ray diffraction, atomic force microcopy, and optical spectra investigations reveal that the lattice and band structure properties of the SSFO films can be modified significantly by varying the Fe content. With Fe content increasing from 0 to 1 in films, the lattice parameters decrease from 4.0425 to 3.8604 A gradually, and the optical band gaps Eg decrease from 4.23 to 2.63 eV linearly. The Fe-induced large tuning in band gap was explained by the systematic width increase of the Fe-derived 3d band lying nearly above the O-derived 2p valence band.

Fabrication and electrochemical performance of delafossite CuFeO2 particles as a stable anode material for lithium-ion batteries

The delafossite CuFeO2 anode materials have been successfully synthesized by hydrothermal process with different temperatures. The X-ray diffraction patterns reveal that two structural polytypes of CuFeO2 with 3R-CuFeO2 and 2H-CuFeO2 are obtained. The results of field-emission scanning electronic microscopy confirm that all CuFeO2 crystals display both hexagonal and rhyombohedral morphologies, which are in good agreement with XRD results. It can be clearly observed that particles sizes of CuFeO2 are increased and the size distributions of particles become broader as hydrothermal temperature increasing. Electrochemical results show that the CuFeO2 particles synthesized at 180xa0°C for 24xa0h display the best electrochemical performance and superior cycle performance. The CuFeO2 materials obtained at 180xa0°C for 24 exhibit a high reversible capacity and high-rate capability (a reversible capability of 390, 276, 185, 133, and 85xa0mA h g−u20091 at 0.1, 0.2, 0.5, 1, 2C, respectively) with good cycling performance (approximate 6.8% capacity loss after 500 cycles at 1C with a capacity retention of 124xa0mA h g−u20091). The excellent electrochemical performance can be attributed to the small particle size and narrow size distributions. It is believed that obtained CuFeO2 crystals as anode materials with high reversible capacity, good rate capability and cyclic stability may be potential candidates for applying in lithium-ion batteries.

Synthesis of chain-like ɑ-Fe/Fe3O4 core/shell composites exhibiting enhanced microwave absorption performance in high-frequency under an ultrathin matching thickness

Coaxial heterogeneous chain-like ɑ-Fe/Fe3O4 composites were synthesized by a facile two-step solvothermal method. The ɑ-Fe nanochains were first obtained by a simple liquid phase reduction process, and the ɑ-Fe/Fe3O4 core/shell composites were prepared by subsequent oxidation process. The electromagnetic properties of ɑ-Fe/Fe3O4 core/shell composites were measured with the coaxial reflection/transmission technique at 1.0–18.0xa0GHz. The ɑ-Fe/Fe3O4 core/shell composites have an optimal absorption peak value of about −u200925.6xa0dB at 16.3xa0GHz and its effective absorption bandwidth lower than −u200910xa0dB reaches 3.6xa0GHz (from 14.4 to 18.0xa0GHz). Importantly, the optimal absorption peak matching thickness of the absorber is only 0.8xa0mm. The enhanced microwave absorption performance is mainly originated from good impedance matching, which is related to low conductivity and magnetic loss of the coaxial heterogeneous chain-like ɑ-Fe/Fe3O4 core/shell composites. The reflection loss results indicate that the ɑ-Fe/Fe3O4 core/shell composites with thin thickness, wide absorption bandwidth and strong absorption characteristics can be used as excellent microwave absorption material in the high-frequency region.

Synthesis and microwave absorbing properties of CeO2/multi-walled carbon nanotubes composites

CeO2/multi-walled carbon nanotubes (CeO2/MWCNTs) composites were successfully synthesized via one-step hydrothermal method. The crystal morphology, structure and electromagnetic parameters of the composites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy and vector network analyzer. The microwave absorption performances of CeO2/MWCNTs composites can be evaluated between 2 and 18xa0GHz frequency range, which is based on transmission line theory. The results demonstrated that fluorite CeO2 nanoparticles were anchored on MWCNTs. The CeO2/MWCNTs composites can reach the minimum reflection loss of −u200934.64xa0dB at 16.24xa0GHz under the coating thickness of 5xa0mm, and the frequency bandwidth exceeding −u200910xa0dB was 2.88xa0GHz. The microwave absorbing properties of the CeO2/MWCNTs composites were mainly attributed to the synergistic effect of dielectric and conductive loss, which were caused by the oxygen vacancies of CeO2. Moreover, charge polarization and interfacial polarization occurring in the composites are beneficial to microwave absorption.

Fe3O4/carbon chain-like core/shell composites: Synthesis and microwave absorption properties

ABSTRACT Fe3O4/carbon core/shell composites were fabricated via a two-step process. Fe3O4/phenol formaldehyde resin (PFR) core/shell composites were first obtained by hydrothermal method, and the Fe3O4/carbon core/shell composites were produced by annealing Fe3O4/PFR core/shell composites under nitrogen flow. The phase structures and morphologies of the composites had been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The microwave absorption properties of the Fe3O4/carbon core/shell composites were measured by vector network analysis (VNA). When the ratio of Fe3O4 and carbon is 1:2 and the sample thickness is 2.4 mm, the Fe3O4/carbon core/shell composites have an optimal absorption peak value of about −45.3 dB at 9.7 GHz and its effective absorption bandwidth lower than −10 dB reaches 2.3 GHz (from 7.8 to 11.1 GHz). The reflection loss results indicate that the Fe3O4/carbon core/shell composites possess higher microwave absorption. The excellent electromagnetic wave absorption properties of the Fe3O4/carbon core/shell composites were attributed to effective complementarities between the dielectric loss and the magnetic loss.