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First-principles methods using the TPSS density functional level of theory with the basis set 6-31G** were applied to study (5-cyanotetrazolato-N) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues in the gas phase. The optimized lowest-energy geometry of CP was calculated from reported experimental structural data using the TPSS method. The calculated values are in good agreement with those measured by X-ray diffraction. Ni, Fe and Zn analogues were constructed and calculated on the same basis. NBO results showed that the metal-ligand interactions have covalent character. Donor-acceptor analyses predicted that the delocalization energy E decreases from Co to Zn, so the covalent nature of the complexes increases in the order Co>Fe>Ni>Zn. In addition, HOMO-LUMO composition was investigated to determine the stability of the title compounds. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A novel hybrid process combining β-MnO2 nanowires oxidation and microfiltration was adopted to remove bisphenol A (BPA), an endocrine disrupting chemical (EDC) in the aquatic environment. The β-MnO2 nanowires synthesized via a facile hydrothermal method were characterized by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscope, and nitrogen sorption. It was demonstrated that β-MnO2 nanowires can degrade BPA effectively. Investigation on operation parameters indicated that oxidation of BPA using β-MnO2 nanowires was evidently dependent on pH, while humic acid and coexisting metal ions such as Ca2+, Mg2+, and Mn2+ induced suppressive effects. After oxidation, a crossflow microfiltration process was conducted to efficiently separate and recover the β-MnO2 nanowires from treated water. Membrane fouling study showed that the as-synthesized β-MnO2 nanowires possess excellent mechanical stability and was able to retain the 1D structure with high aspect ratios after reaction, thus significantly reducing membrane pore blocking in the microfiltration process. [Copyright &y& Elsevier]

Transition metal oxides have attracted considerable attention as anode materials of lithium-ion batteries (LIBs). However, poor electrical conductivity and huge volume change hinder their practical application. Porous nanostructure is vital to attain high-performance lithium-ion batteries. Herein, we have designed and fabricated regularly porous ZnFe 2 O 4 nanospheres consisted of small primary nanoparticles via a facile hydrothermal method followed by calcination. The structural properties and morphology of the sample are characterized by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The composite is then evaluated as anode for Li-ion battery and shows excellent electrochemical properties. The reversible capacity of 868.9 mAh g −1 can be obtained at 200 mA g −1 over 80 cycles. Furthermore, the discharge capacity can still retain 456 mAh g −1 after 600 cycles at a high charge rate of 2 A g −1 . Our findings reveal that ZnFe 2 O 4 sample is a promising anode material for LIBs due to its superior rate capability and long cycle life. [ABSTRACT FROM AUTHOR]

Abstract: WO3 nanofibers were synthesized using an electrospinning method and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The obtained WO3 nanofibers were used as sensitive materials for the detection of NH3. Indirect-heating sensors based on WO3 nanofibers were prepared. When the WO3 nanofiber-based sensors were exposed to 100ppm NH3 at 500°C, the response is 5.5, and the response and recovery times are 1 and 5s, respectively. These results indicate that the gas sensors based on WO3 nanofibers express high and fast response and recovery characteristics to NH3, and the WO3 nanofibers are promising sensitive materials for NH3 detecting. [Copyright &y& Elsevier]