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Shuttle effect and the low utilization of dissolved lithium polysulfides (LiPSs) are two prevailing concerns in Li-S battery (LSB) research. Energy efficiency on the other hand is often overlooked but vital to the commercial deployment of battery technology. In this work, a composite of hyperbranched poly­(amidoamine)-modified multiwalled carbon nanotubes (PAMAM-CNTs) is successfully prepared by chemical grafting and employed as an interlayer material in LSBs. The high content and highly dispersed polar functional groups of PAMAM can efficiently adsorb and enhance the redox reaction of LiPSs. The CNTs function as a scaffold and current collector that reduces the internal polarization. The assembled LSB displays a high energy efficiency of 86% and a low capacity fading rate of 0.037% per cycle over 1200 cycles at 2 C. The cell also shows excellent cycle performance, high sulfur utilization, and improved stability at a high areal capacity of 9 mAh cm–2 (achieved at a sulfur loading of 8.7 mg cm–2) and low electrolyte/sulfur ratio of 6.1 mL g–1. This thin (12 μm) and lightweight (0.34 mg cm–2) interlayer has a negligible impact on the overall cell energy density.

SUMMARYIn this paper, activated aluminum powder was prepared by magnetic grinding with a homemade equipment and hydrolyzed in alkaline solution to produce hydrogen. The results showed that the prepared aluminum powder could improve hydrolysis reactivity effectively and have high hydrogen yield in alkaline solution (up to 1340 mL/g). It was found that grinding time, reaction temperature and grinding media could significantly affect the hydrolysis reaction while alloy components had little effect. Aluminum powder ground for 40 min can produce hydrogen 1340 mL/g within 6 min under optimal reaction temperature of 323 K. Copyright © 2013 John Wiley & Sons, Ltd.

A new sulfonic/carboxylic dual-acid catalyst based on sulfur-rich graphene oxide (GO-S) was readily prepared and used as a highly efficient and reusable solid acid catalyst toward the esterification of oleic acid with methanol for biodiesel production. Higher yields of methyl oleate (98 %) and over 3 times higher turnover frequencies (TOFs) were observed for the GO-S dual-acid catalyst, compared to liquid sulfuric acid or other carbon-based solid acid catalysts. The "acidity" of sulfonic acid groups was enhanced by the addition of carboxylic acid groups as the combination of the two acids enhances their inherent activity by associative interaction.

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Heterogeneous acidic catalysts offer many advantages such as lower corrosion, easier separation and lower production cost compared with homogeneous sulfuric acid. Graphene oxide (GO) containing trace amount of oxygen-containing functional groups have been demonstrated to be effective carbon-based solid acid catalyst. However, GO are difficult to be recovered from liquid reaction system for further utilization. Graphene oxide/Polyethersulfone (PES) catalytic membranes were prepared and employed as heterogeneous acid catalysts in the esterification of oleic acid with methanol for biodiesel production. The membrane was annealed at different temper-atures to promote the catalytic activity and reusability. As predicted, the OA conversion increased greatly with the increase of GO content in the membrane. Both internal and external diffusion have no influence on the catalytic activity. The catalytic membrane dosage, reaction temperature and methanol/oleic acid molar ratio affected its catalytic performance significantly. Among all the prepared membranes, the membrane annealed at 150°C exhibited the best catalytic performance, with a conversion of over 85 % even after six cycles.