Research Highlights

Graphene-based gas sensor

doi:10.1038/nindia.2012.75 Published online 18 May 2012

Researchers have designed a new type of sensor that can detect minute traces of nitrogen dioxide, a polluting gas. The sensor, made from a nanocomposite of graphene and tungsten oxide, will be very useful in reducing the amount of nitrogen dioxide produced by industry.

Graphene has a larger surface area than carbon nanotubes, thus offering additional improvements. The surface of graphene is also extremely sensitive to the attachment or detachment of gas molecules.

To explore the gas-sensing potential of graphene, the researchers first synthesized graphene oxide and then reduced it to graphene. They added different amounts of graphene (0.2, 0.5 and 1.0 wt%) to tungsten oxide, yielding three different nanocomposite samples. Next, they smeared layers of five different samples — graphene only, pure tungsten oxide and the three nanocomposites — on an alumina sensor substrate.

The researchers studied the gas-sensing properties of each layer at temperatures in the range of 200–300°C. At room temperature, they carried out gas-sensing measurements for different concentrations (1, 5, 10 and 20 ppm) of nitrogen dioxide in air.

The sensor based on tungsten oxide–graphene (0.2 wt%) exhibited a good response even at gas concentrations below 5 ppm. The sensor response rose further with an increase in the amount of graphene (0.5 wt%). At room temperature, the tungsten oxide–graphene sensor's response to nitrogen dioxide was nearly three times higher than that of a pure tungsten oxide layer.

The researchers say that a graphene concentration of 0.5 wt% in the nanocomposite layer is optimum for gas-sensing applications.

The authors of this work are from: Physics of Energy Harvesting, Sophisticated and Analytical Instruments, and Apex Level Standards and Industrial Metrology, National Physical Laboratory, New Delhi, India.


References

  1. Srivastava, S. et al. Faster response of NO2 sensing in graphene–WO3 nanocomposites. Nanotechnology 23, 205501 (2012)  | Article | PubMed |