Improving gas sensing properties of graphene by introducing dopants and defects: a first-principles study

Abstract

The interactions between four different graphenes (including pristine, B or N doped and defective graphenes) and small gas molecules (CO, NO, NO 2 and NH 3 ) were investigated by using density functional computations to exploit their potential applications as gas sensors. The structural and electronic properties of the graphene-molecule adsorption adducts are strongly dependent on the graphene structure and the molecular adsorption configuration. All the four gas molecules show much stronger adsorption on the doped or defective graphenes than that on the pristine graphene.The defective graphene shows the highest adsorption energy with CO, NO and NO 2 molecules, while the B-doped graphene gives the tightest binding with NH 3 . Meanwhile, the strong interactions between the adsorbed molecules and the modified graphenes induce dramatic changes to graphene's electronic properties. The transport behavior of a gas sensor using B-doped graphene shows a sensitivity two orders of magnitude higher than that of pristine graphene. This work reveals that the sensitivity of graphene based chemical gas sensors could be drastically improved by introducing appropriate dopant or defect.1

Changes in work function due to NO2 adsorption on monolayer and bilayer epitaxial graphene on SiC(0001)

“…In agreement with previous DFT calculations, we find that the energetically favorable configuration of NO 2 on 1LG is that of cycloaddition, i.e., bonding via both oxygen ends, on a bridge site [19,37]. It is adsorbed at an average height of 3.34Å from the graphene plane [38].…”

Chemical sensing with switchable transport channels in graphene grain boundaries

“…It was shown that the sensitivity of an isolated GB is B300 times higher than that of a single graphene grain and much larger than that of polycrystalline graphene sensors. We have verified that the presence of local transport gaps in GBs together with the local accumulation of gas molecules plays a crucial role in the observed large chemical sensitivity of GBs, so the mechanism differs from the previously reported carrier density modulation in carbon-based sensors 6,7,[23][24][25][26][27][28] . The sensing mechanism is based on a marked closing or opening of local conduction channels through the GB by the adsorbed …”

“…T opological defects improve the sensitivity of carbon-based chemical sensors towards gas molecules due to an efficient physisorption and enhanced charge transfer process [1][2][3][4][5][6][7] . Since such defects are formed within a single-crystalline graphene lattice, they have a modest effect on the electronic properties of the device.…”

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

“…The adsorption process typically involves changes in the physical or chemical properties of the adsorbed molecule and the adsorbing surface. For example, the change in the electronic properties of some graphene structures has been used for molecular sensing [10][11][12]. Modelling these systems is important for a complete understanding and prediction of their properties so that sensor paradigms can be designed.…”