High gas-sensing selectivity of bilaterally edge-doped graphene nano-ribbons towards detecting NO₂, O₂ and SO₃ gas molecules: Ab-initio investigation

The adsorption and gas-sensing properties of B/N edge-doped graphene nano-ribbons (GNRs) are investigated using state-of-the-art computational technique, which is based on a combination of density-functional theory (DFT) and non-equilibrium Green's functions (NEGF) formalism. First, the assessment of the effects dopants’ positions, with respect to edges of GNR, on the transport properties has revealed that the bilaterally B/N edge-doping of GNR would yield negative-differential resistance (NDR) IV-characteristics, due to the back-scattering events. Then, the double-edge-doped GNR:B and GNR:N were used to study the gas-sensing properties. The results of adsorption tests show that chemisorption processes can be attained for NO₂ and O₂ molecules on GNR:B and SO₃ molecule on GNR:N. Furthermore, the results of calculations of transport properties show that the chemisorption processes of these molecules can yield enormous rectifications to the IV-characteristics to sweep the NDR behaviors and should consequently yield large sensors responses in GNR-based devices. Comparison to many other gases is performed and it is concluded that edge-doping in both GNR:B and GNR:N would yield exceptionally high selectivity towards detecting toxic NO₂ and SO₃ gases, respectively. The combined GNR:B- and GNR:N-based sensors are suggested to be used as gas-sensor and alarm-sensor for NO₂ gas, respectively. Our theoretical findings are corroborated with available experimental data.