Researchers create carbon net to catch toxic gases

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Researchers at the University of Manchester have developed a way of using ultra thin layers of carbon to detect even a single molecule of a toxic gas.

Three years ago, Manchester scientists discovered graphene, a one-atom-thick gauze of carbon atoms in a hexagonal structure that resembles chicken wire, but obtaining it was a difficult process.

Recently, a range of possible uses for graphene have been uncovered by scientists, including research into using it as a replacement for silicon in micro-circuitry.

Working with researchers from the Institute for Microelectronics Technology in Russia and the Institute for Molecules and Materials at the University of Nijmegen in the Netherlands, the same Manchester team has found that graphene is extremely sensitive to the presence of minute amounts of gases such as alcohol vapour or extremely toxic carbon monoxide.

The result came as a surprise to researchers who considered graphene to be completely chemically inert.

The researchers have shown that gas molecules gently attach themselves to graphene without disrupting its chicken wire structure. The attachment adds or takes away electrons from the graphene molecules, which results in measurable changes in its electrical conductance.

"This level of sensitivity is typically millions of times higher than for any other gas detector demonstrated before. Graphene sensors are as sensitive as sensors can be in principle," said Dr Kostya Novoselov, from the school of physics and astronomy.

While this is a significant breakthrough, the team stressed that further research is needed to make such detectors sensitive to individual gases.

This sensitivity is a problem suffered by all solid-state gas detectors and is usually solvable using filters and analysis of a temperature response.

"At present you could not sniff out a flammable substance hidden in luggage because an increase in air humidity would give false readings," added fellow researcher Professor Andre Geim.

"This is only the first step on the route to commercial graphene-based sensors, but the road ahead is clear. Once again, graphene has proved itself to be a material with truly remarkable qualities, allowing observations that no other known material could do."
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