Investigation of BN modified graphene nanoribbon for gas adsorption applications: DFT study

Abstract

Graphene nanoribbons that are modified using boron and nitrogen (CBN) are examined in this work for their adsorption of CO, CO2, H2, H2O, NH3, NO, and NO2 gases. A first principles approach that utilizes density functional theory (DFT) computation is employed to investigate both perfect and vacancy defected structures. The gas molecule adsorption capacity is examined in this work by determination of the adsorption energy (Ed), adsorption length (D), charge exchanged amongst the gas and CBN (ΔQ), along with the density of states (DOS). The results indicate that NO and NO2 gases have favorable adsorption on the perfect CBN, however, chemisorption is not achieved for these gases. On the other hand, NO2 and NH3 gases have favorable adsorption on the vacancy defected CBN and they establish chemical bonds with the structure. Ed is 235% and 165% for NO2 and NH3, respectively, higher for the vacancy defected nanoribbon relative to the perfect nanoribbon. Furthermore, the adsorption length of NO2 and NH3 decreases dramatically for the vacancy defected CBN to 1.55 and 1.69 Å, while the charge transferred increases to 0.326 and -0.415 e, respectively. The sensor response evaluation indicates that the vacancy defected CBN structure exhibits an enhanced response towards NO2 gas followed by that of NH3. Consequently, the introduction of a vacancy defect in the CBN structure is an efficient approach to enhance its sensitivity and selectivity, particularly, for NO2 and NH3.