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Volcanoes could churn out carbon nanotubes

发布时间:2019-03-01 13:06:10来源:未知点击:

By Will Knight Volcanoes could be used to churn out large quantities of carbon nanotubes and nanofibres, researchers say. They found cooled volcanic lava to be a surprisingly efficient ready-made chemical trigger for synthesising the nanostructures. Dang Sheng Su and Xiao-Wie Chen at the Fritz Haber Institute of the Max Planck Society in Berlin, Germany, used lava collected from Mount Etna in Italy to chemically synthesise nanoscale carbon structures in the lab. Nanotubes and nanofibres made from carbon have unusual mechanical and electrical properties and have shown promise as catalysts, filters and even nanoscopic electronic components. They are normally created by firing a laser or an arc of electricity through powdered carbon, or by chemically depositing vapourised carbon on top of a chemically reactive material, or substrate. However, none of these techniques can produce carbon nanostructures in very large quantities. Su and Chen realised that volcanic lava could provide a solution to the problem of synthesising a substrate and catalyst (usually from silica or alumina) for chemical vapour deposition. They predicted that lava, which has similar chemical properties, might provide a ready-made substrate and catalyst instead. To test the hunch they experimented with chunks of lava collected from Mount Etna – the highest and most active volcano in Europe. The pair first pulverised the rock, heated it to 700°C and then passed a mixture of hydrogen and ethylene gas over the powder. Elemental iron particles in the powered lava catalysed the decomposition of ethylene, producing elemental carbon – in the form of nanotubes and fibres. The process is relatively simple and, since lava is naturally abundant, it could provide a way to synthesise large quantities of carbon nanotubes and fibres, the researchers say. Su and Chen hope their work will lead to new industrial applications for the materials. “It could pave the way for further exploitation of the superior properties of tailored, nanostructured carbon for large-scale applications, such as catalysis and water purification by absorption,” they say. “It is fascinating to know that nanotubes can be made using a naturally occurring catalyst,” says Peter Harris at the University of Reading in the UK. “This raises the possibility that they might one day be found in a geological deposit.” But Harris questions the idea of using lava for grand-scale nanotube production. “As a commercial way of making nanotubes there would be problems with using a catalyst which contains all sorts of unknown impurities,” he notes. “In any case, the currently used catalysts are not particularly expensive.” Journal reference: Angewandte Chemie International Edition (DOI: