A simply effective double-coating cathode with MnO2 nanosheets/graphene as functionalized interlayer for high performance lithium-sulfur batteries

Herein, we report a facile and effective adsorption strategy to improve the performance of Lithium-Sulfur (Li-S) batteries. MnO₂ nanosheets grown on the surface of highly conductive graphene resulted in a coupled composite bilayer electrode when coated onto a sulfur cathode. In this way, a high initial specific capacity of 1395 mA h g^-1 at a rate of 0.5C, a coulombic efficiency approaching 100% and steady cyclic efficiency with a fade rate of 0.3% per cycle from 10 to 100 cycles has been achieved. This hybrid electrode not only shows enhanced electrochemical performance but can also be easily controlled and scaled thereby aiding future commercialization of high-performance Li-S batteries.

Preparation and characterization of Pr0.6Sr0.4FeO3-δ-Ce0.9Pr0.1O2-δ nanofiber structured composite cathode for IT-SOFCs

In this work, Pr_0.6Sr_0.4FeO_3-δ -Ce_0.9Pr_0.1O_2-δ (PSFO-CPO) nanofibers were synthesized by a one-step electrospin technique for use in intermediate-temperature solid oxide fuel cell (IT-SOFC) applications. PSFO-CPO nanofibers were produced with a diameter of about 100nm and lengths exceeding tens of microns. The thermal expansion coefficient (TEC) matches with standard GDC electrolytes and the resulting conductivity also satisfies the needs of IT-SOFCs cathodes. EIS analysis of the nanofiber structured electrode gives a polarization resistance of 0.072Ωcm² at 800°C, smaller than that from the powdered cathode with the same composition. The excellent electrochemical performance can be attributed to the well-constructed microstructure of the nanofiber structured cathode, which promotes surface oxygen diffusion and charge transfer processes. All the results imply that the one-step electrospin method is a facile and practical way of improving the cathode properties and that PSFO-CPO is a promising cathode material for IT-SOFCs.

An effective three-dimensional ordered mesoporous CuCo2O4 as electrocatalyst for Li-O2 batteries

Three-dimensional ordered mesoporous (3DOM) CuCo₂O₄ materials have been synthesized via a hard template and used as bifunctional electrocatalysts for rechargeable Li-O₂ batteries. The characterization of the catalyst by X-ray diffractometry and transmission electron microscopy confirms the formation of a single-phase, 3-dimensional, ordered mesoporous CuCo₂O₄ structure. The as-prepared CuCo₂O₄ nanoparticles possess a high specific surface area of 97.1 m² g^{- 1} and a spinel crystalline structure. Cyclic voltammetry demonstrates that mesoporous CuCo₂O₄ catalyst enhances the kinetics for either oxygen reduction reaction (ORR) or oxygen evolution reaction (OER). The Li-O₂ battery utilizing 3DOM CuCo₂O₄ shows a higher specific capacity of 7456 mAh g^{- 1} than that with pure Ketjen black (KB). Moreover, the CuCo₂O₄-based electrode enables much enhanced cyclability with a 610 mV smaller discharge-recharge voltage gap than that of the carbon-only cathode at a current rate of 100 mA g^{- 1}. Such excellent catalytic performance of CuCo₂O₄ could be associated with its larger surface area and 3D ordered mesoporous structure. The excellent electrochemical performances coupled with its facile and cost-effective way will render the 3D mesoporous CuCo₂O₄ nanostructures as attractive electrode materials for promising application in Li-O₂ batteries.

Extracellular vesicle biogenesis in helminths: more than one route to the surface?

The quite recent discovery that parasites release extracellular vesicles (EVs) that can transfer a range of effector molecules to host cells has made us re-think our understanding of the host-parasite interface. In this opinion article we will consider how recent proteomics and transcriptomics studies, together with ultrastructural observations, suggest that more than one mechanism of EV biogenesis can occur in helminths. We propose that distinct EV sub-types have roles in immune-modulation and repair of drug-induced damage, and put forward the case for targeting EV biogenesis pathways to achieve parasite control. In doing so we raise a number of outstanding research questions that must be addressed before this can happen.