X-shaped hollow α-FeOOH penetration twins and their conversion to α-Fe2O3 nanocrystals bound by high-index facets with enhanced photocatalytic activity

通讯作者地址: Wang, ZCNonspherical hollow nanoparticles (NHNPs) have attracted a great deal of attention in recent years due to their unique properties and many promising applications. However, compared to hollow spheres, the fabrication of NHNPs is generally much more difficult and there are only a few successful examples to date. In this work, X-shaped hollow alpha-FeOOH penetration twins were first synthesized by a facile hydrothermal reaction. X-shaped alpha-Fe2O3 hollow nanostructures with high-index {11 (2) over bar3} facets exposed were further obtained via the topotactic transformation of alpha-FeOOH precursor. To the best of our knowledge, this is the first report on the nanostructures with high-index facets as well as a hollow interior. Owing to the special hollow structure and the high-energy surface, the as-obtained alpha-Fe2O3 nanocrystals show excellent visible-light photocatalytic activity toward the degradation of RhB.State Key Development Program for Basic Research of China 2007CB935603 National Natural Science Foundation of China 5137221

A novel Li(2)FeSiO(4)/C composite: Synthesis, characterization and high storage capacity

A Li(2)FeSiO(4)/C composite material has been prepared via a solution-polymerization approach. The composite is characterized by X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and superconducting quantum interference device (SQUID). The electrochemical performance of the Li(2)FeSiO(4) is greatly enhanced and the initial discharge capacity is similar to 220 mA h g(-1), when it is cycled between 1.5-4.8 V. This indicates that more than one lithium ion can be extracted out of the Li(2)FeSiO(4) lattice. At high current densities, the Li(2)FeSiO(4)/C also exhibits excellent rate capability and cycling stability. This indicates that it is a very promising cathode material for next generation lithium-ion batteries.National Natural Science Foundation of China[20873115, 20473068, 29925310]; National Basic Research Program[2007CB209702, 2011CB905903

Syntheses and characterizations of rare earth compounds RE(HCO2)(3)(HNO2) (H2CO2) (RE = Y, Tb, Dy, Ho, Er, Yb, Tm)

A series of novel inclusion compounds with compositions of RE(HCO2)(3)(HNO2)( H2CO2) (RE = Y, Tb, Dy, Ho, Er, Yb, Tm) were synthesized and structures were characterized by X-ray methods. The orthorhombic structure was shown to be a new type with a non-centrosymmetric space group (20) C222(1) by single crystal structure determinations. It is characterized by networks of rare earth centered square anti-prisms formed by eight oxygen atoms through bridging carbon and nitrogen atoms. The guest formic acid molecules H2CO2 are distributed inside the open tunnels along the crystallographic a axis. The magnetic susceptibility measurements show the heavy rare earth compounds follow the Curie-Weiss law and the calculated numbers of Bohr magnetons are consistent with the RE3+ ions. The yttrium compound shows very weak temperature independent paramagnetism

Hematite concave nanocubes and their superior catalytic activity for low temperature CO oxidation

Hematite (α-Fe2O3) concave nanocubes bound by high-index {1344} and {1238} facets were synthesized and their catalytic activity for CO oxidation were also investigated. ? 2014 the Partner Organisations

Hazards and Improvement Measures of Microplastic Pollution: A Review

Microplastics is one category of plastics with relatively small diameter and is considered as the common ingredient of waste accumulation zone in oceans. However, since countless plastic products are emitted into oceans annually as waste all around the world, pollution caused by them is severe and the resulting problems have attracted attention globally, while current policies and cooperation around the globe for tackling microplastics pollution still need to be improved. To deal with microplatics-related problems in the ocean, our review first discussed the toxicity of microplastics based on previous research related to marine microplastics, which was caused by the plastics themselves and their leaching substances with impacts on marine creatures and human body along the food chain. After summarizing some measures that have been already performed, we suggested that the authority should take more actions to mitigate those problems resulted from microplastics, pay more attention on researching, and encourage citizens to offer their proposals. By finally analyzing the advantages and disadvantages of different handling methods, as well as physical, chemical, and biological treatment technologies on oceanic microplastic issues, our work provided experience on disposing microplastics waste under various actual situations with an example for more holistic waste treatment

Iron-catalytic growth of prism-shaped single-crystal silicon nanowires by chemical vapor deposition of silane

Single-crystal silicon nanowires with the prism structures were synthesized by chemical vapor deposition of SiH4 gas at 450 degrees C. Fe particles which were located at the tip of the CNTs were employed as a catalyst for the growth of silicon nanowires (SiNWs). Transmission electron microscopy studies of the materials showed that the nanowires have a diameter of 50-70 nm and a length of several micrometers. High-resolution transmission electron microscopy demonstrated that the nanowires have excellent single-crystal characteristics. Both the CNTs and Fe play a key role in the growth process of the SiNWs. A growth mechanism was proposed for the growth of silicon nanowires under our experimental conditions. (c) 2005 Elsevier B.V. All rights reserved

Synthesis and luminescence properties of the lithium-containing lanthanum-oxycarbonate-like borates

The lithium-containing lanthanum-oxycarbonate-like borate, Li0.6La2O2.25(BO3)(0.7), has been synthesized by solid-state reactions and was found to be isostructural with the type II lanthanum-oxycarbonate La2O2(CO3). The new compound, lithium-containing lanthanum-oxycarbonate-like borate Li0.6La2O2.25(BO3)(0.7) has been synthesized and its structure characterized by the Rietveld method using powder X-ray diffraction data. It crystallizes in space group P6(3)/mmc with lattice parameters of a=b=4.03396(3) angstrom, c=16.5863(2) angstrom, V=233.746(4) angstrom(3). The mechanism of the lithium incorporation in the borate is that four Li+ cations replace one (B2O)(4+) group. i.e. Li0.6La2O2.25(BO3)(0.7) can be described as Li2xLa2O1.5+2.5x(BO3)(1-x), x=0.3 and the lithium incorporation stabilized the type II borate. The luminescent properties of Li0.6La2O2.25(BO3)(0.7) doped with Eu3+ were studied, indicating a potential application in white light emitting diodes (WLEDs). (C) 2012 Elsevier Inc. All rights reserved.National Natural Science Foundation of China [21171176, 10979027, 20871121

The synergistic effects of Al and Te on the structure and Li+-mobility of garnet-type solid electrolytes

The cubic garnet-type solid electrolyte Li7La3Zr2O12 with aliovalent doping exhibits a high ionic conductivity. However, the synergistic effects of aliovalent co-doping on the ionic conductivity of garnet-type electrolytes have rarely been examined. In this work, the synergistic effects of co-dopants Al and Te on the ionic conductivity of garnets were investigated using X-ray diffraction (XRD), 27Al/6Li Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR), Energy Dispersive X-ray Spectroscopy (EDS), Neutron Powder Diffraction (NPD) and Alternating Current (AC) impedance measurements. It was shown that co-dopants Al and Te stabilized the cubic lattice of Li7-2x-3yAlyLa3Zr2-xTexO12 with specific Al/Te ratios, where additional Al had to be included in the structure if the amount of doped Te content x was below 0.5. In the Al and Te co-doped crystal structure, Al was incorporated into the tetrahedral 24d sites of lithium and Te occupied 16a sites of Zr. It was revealed that the occupancy of the latter could suppress the insertion of Al. High-resolution 6Li MAS NMR was able to differentiate the two lithium sites of interest in the garnet structure. Furthermore, it was shown that the mobility of Li ions at 24d sites mainly determined the bulk conductivities of garnet-type electrolytes

Understanding the High Capacity of Li2FeSiO4: In Situ XRD/XANES Study Combined with First-Principles Calculations

National Natural Science Foundation of China [21233004, 21021002, 20873115, 11004165]; National Basic Research Program (973 Program) [2011CB935903]; General Motors (USA)The electrochemical mechanism of the cathode material Li2FeSiO4 with reversible extraction/insertion of more than one Li+ from/into the structure has been studied by techniques of in situ synchrotron X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD). These advanced techniques provide effective solutions to address the limitations of characterization by traditional ex situ methods. The study of in situ Fe Kedge XANES indicates that the Fe ion in the Li2FeSiO4 is oxidized continuously to high valence during the charging process from open circuit potential to 4.8 V, which contributes to the high reversible capacities of the materials. In situ XRD and theoretical study from first-principles calculations have been employed to reveal the structural evolution of the Li2FeSiO4 underlying the high capacity during the charge/discharge process. The results of both experimental and theoretical studies are consistent and indicate that Li2FeSiO4 undergoes two two-phase reactions when the electrode is charged to a high voltage of 4.8 V