A dash of boron added to graphene converts it to an ultrasensitive gas sensor, according to work from an international collaboration. Graphene is now well known for its strength and electronic properties, but doping it with boron atoms allows it to be used to detect nitrogen oxides and ammonia at very low concentrations, parts per billion and parts per million, respectively, a 27 times and 10000 times improved sensitivity on undoped, pristine, graphene. The work could open the way to high-performance sensors for trace detection of noxious and toxic gases. [Terrones et al, Proc Natl Acad Sci, 2015; doi:10.1073/pnas.1505993112]
"This is a project that we have been pursuing for the past four years, " explains Mauricio Terrones of Pennsylvania State University. "We were previously able to dope graphene with atoms of nitrogen, but boron proved to be much more difficult. Once we were able to synthesize what we believed to be boron graphene, we collaborated with experts in the United States and around the world to confirm our research and test the properties of our material."
Boron compounds are often very air sensitive and decompose rapidly but the team was able to fabricate highly-crystalline, centimeter-square sheets of boron-graphene in their "bubbler-assisted" chemical vapor deposition system. Colleagues at the Honda Research Institute USA in Columbus, Ohio, tested the samples against their own highly sensitive gas sensors while Konstantin Novoselov's team at the University of Manchester, UK, investigated the transport mechanism of the sensors. Collaborators in Belgium and the USA corroborated what the team was seeing in its scanning tunneling microscopy images and experimental images and confirmed that the boron atoms in the graphene lattice can interact with ammonia or nitrogen oxide molecules. Additional data came from colleagues in China and Japan.
"This multidisciplinary research paves a new avenue for further exploration of ultrasensitive gas sensors," explains Honda's Avetik Harutyunyan. "Our approach combines novel nanomaterials with continuous ultraviolet light radiation in the sensor design that have been developed in our laboratory by lead researcher Gugang Chen in the last five years. We believe that further development of this technology may break the parts per quadrillion level of detection limit, which is up to six orders of magnitude better sensitivity than current state-of-the-art sensors."
The team suggests that the new boron-graphene sensors could be used at the laboratory level, in industry and in environmental studies. The theoretical work also suggests that the properties of the same materials might make them useful in electronics applications such as improved rechargeable batteries and as field-effect transistors.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the bestselling science book "Deceived Wisdom".