May 08, 2014 |
Dipping graphene in solutions to generate electricity
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(Nanowerk News) A new method for generating electricity, by simply dipping a piece of graphene sheet into a common ionic solution, is reported in Nature Communications this week ("Waving potential in graphene"). This electric energy harvesting approach could be integrated into cost-effective, self-powered sensor designs.
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Attempts have been made to produce electricity with graphene based systems, but it is unconfirmed whether or not convincing or considerable amounts of electricity have been obtained.
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Research carried out by Wanlin Guo and colleagues now adopts a different approach. In contrast to all the previous attempts in which graphene or other carbon-based materials are completely immersed in flowing solutions, the researchers move a graphene sheet across the surface of an ionic solution, such as sodium chloride.
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They show that with a piece of graphene about the size of a small ruler (2 x 10 cm2), the electricity generated is approximately 10 microempheres and, while this is still a relatively small output, the authors demonstrate that it is enough to stimulate a sciatic nerve of a frog.
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Importantly, they also show that the electricity generated is proportional to the size of the graphene sheet and the dipping speed, suggesting that this device may be scalable.
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The researchers further explain that the key to producing electricity in their experiments is to maintain a gas-liquid interface while dipping graphene. This moving gas-liquid boundary induces charge transfer in graphene, which they term‘waving potentia’,leading to electricity generation.
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