Design and analysis of a 2D grapheneplus (G+)-based gas sensor for the detection of multiple organic gases†

Abstract

A new member of the 2D carbon family, grapheneplus (G+), has demonstrated excellent properties, such as Dirac cones and high surface area. In this study, the electronic transport properties of G+, NG+, and BG+ monolayers in which the NG+/BG+ can be obtained by replacing the center sp³ hybrid carbon atoms of the G+ with N/B atoms, were studied and compared using density functional theory and the non-equilibrium Green's function method. The results revealed that G+ is a semi-metal with two Dirac cones, which becomes metallic upon doping with N or B atoms. Based on the electronic structures, the conductivities of the 2D G+, NG+ and BG+-based nanodevices were analyzed deeply. It was found that the currents of all the designed devices increased with increasing the applied bias voltage, showing obvious quasi-linear current–voltage characteristics. I_G+ was significantly higher than I_NG+ and I_BG+ at the same bias voltage, and I_G+ was almost twice I_BG+, indicating that the electron mobility of G+ can be controlled by B/N doping. Additionally, the gas sensitivities of G+, NG+, and BG+-based gas sensors in detecting C₂H₄, CH₂O, CH₄O, and CH₄ organic gases were studied. All the considered sensors can chemically adsorb C₂H₄ and CH₂O, but there were only weak van der Waals interactions with CH₄O and CH₄. For chemical adsorption, the gas sensitivities of these sensors were considerably high and steady, and the sensitivity of NG+ to adsorb C₂H₄ and CH₂O was greater as compared to G+ and BG+ at higher bias voltages. Interestingly, the maximum sensitivity difference for BG+ toward C₂H₄ and CH₂O was 17%, which is better as compared to G+ and NG+. The high sensitivity and different response signals of these sensors were analyzed by transmission spectra and scattering state separation at the Fermi level. Gas sensors based on G+ monolayers can effectively detect organic gases such as C₂H₄ and CH₂O, triggering their broad potential application prospects in the field of gas sensing.