Three-dimensional mesoporous γ-Fe2O3@carbon nanofiber network as high performance anode material for lithium- and sodium-ion batteries.

Electrode materials that can function well in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) are desirable for electrochemical energy storage applications, especially under high rate. In this work, a three-dimensional (3D) mesoporous γ-Fe2O3@carbon nanofiber (γ-Fe2O3@CNF) mat has been successfully synthesized by sol-gel based electrospinning and carbonization. It delivers a specific capacity of 820 mAh g-1 at 0.5 C after 250 cycles, 430 mAh g-1 at 6 C after 1000 cycles, and 222 mAh g-1 at ultrahigh rate of 60 C for LIBs, while for SIBs it delivers a specific capacity of 360 mAh g-1 at 1 C after 1000 cycles and 130 mAh g-1 at 60 C. Besides, the result of ex situ microstructure examination shows the polycrystalline nature of γ-Fe2O3 nanoparticle still exists in LIB even after 1000 cycles, while it vanishes in SIB, suggesting that the relatively larger volume expansion occurred during Na+ insertion/deinsertion, resulting in pulverization of the particles. The CNFs maintained their pristine 3D network structure after the charge/discharge, which demonstrated the critical role of a robust conductive electrode in promoting fast Li+/Na+ transportation. More importantly, they act as an electrical bridge between Li+/Na+ and γ-Fe2O3 nanoparticles, therefore suppressing the cell impedance growth and γ-Fe2O3 volume expansion, resulting in the enhancement in both cyclic and rate capability.

Flake-like InVO4 modified TiO2 nanofibers with longer carrier lifetimes for visible-light photocatalysts.

Highly efficient solar light absorption capabilities and quantum yields in photocatalysts are key to their application in photocatalytic fields. Towards this end, TiO2/InVO4 nanofibers (NFs) have been designed and fabricated successfully by a one-pot electrospinning process. The resulting TiO2/InVO4 NFs display excellent visible-light photocatalytic activity, owing to their prominent visible-light absorption and electron-hole separation properties. Time-resolved transient PL spectroscopy demonstrated that the TiO2/InVO4 NFs display longer emission decay times (22.0 ns) compared with TiO2 NFs (15.5 ns), implying that the heterojunction can remarkably suppress the electron-hole recombination and promote the carrier transfer efficiency. With tailored heterostructure features, TiO2/InVO4 NFs exhibit superior visible-light photodegradation activity, and after 80 min of visible-light irradiation, almost 95% of RhB molecules can be decomposed by TiO2/InVO4 NFs, while only 18% of RhB molecules can be decomposed by pure TiO2 NFs.

Sepiolite/CNT/S@PANI composite with stable network structure for high performance lithium sulfur batteries.

Composite materials with a stable network structure consisting of natural sepiolite (Sep) powders, carbon nanotubes (CNTs) and conductive polymer (PANI) have been successfully synthesized using a simple vacuum heat treatment and chemical oxidation method, and they have been used as cathode materials for lithium sulfur batteries. It is found that Sep/CNT/S@PANI composites possess high initial discharge capacity, good cyclic stability and good rate performance. The initial discharge capacity of the Sep/CNT/S@PANI-II composite is about 1100 mA h g-1 at 2C, and remained at 650 mA h g-1 after 300 cycles, and the corresponding coulombic efficiency is above 93%. Such performance is attributed to specific porous structure, outstanding adsorption characteristics, and excellent ion exchange capability of sepiolite, as well as excellent conductivity of CNT. Furthermore, the PANI coating has a pinning effect for sulfur, which enhances the utilization of the active mass and improves the cycling stability and the coulombic efficiency of the composites at high current rates.

Alcohol-soluble electron-transport small molecule for fully solution-processed multilayer white electrophosphorescent devices.

A novel alcohol-soluble electron-transport material was designed and synthesized. This material not only possesses a high triplet energy and a low HOMO level but also exhibits excellent electron-transport properties and good film-forming ability. Efficient fully solution-processed multilayer white electrophosphorescent devices have been fabricated by using this alcohol-processable material as an orthogonal electron-transport layer.