First-Principles Study of χ₃-Borophene as a Candidate for Gas Sensing and the Removal of Harmful Gases

The potential application of borophene as a sensing material for gas-sensing devices is investigated in this work. We utilize density functional theory (DFT) to systematically study the adsorption mechanism and sensing performance of χ₃-borophene to search for high-sensitivity sensors for minor pollutant gases. We compare the results to those for two Pmmn borophenes. The first-principles calculations are used to analyze the sensing performance of the three different borophenes (2 Pmmn borophene, 8 Pmmn borophene, and χ₃-borophene) on five leading harmful gases (CO, NH₃, SO₂, H₂S, and NO₂). The adsorption configuration, adsorption energy, and electronic properties of χ₃-borophene are investigated. Our results indicate that the mechanism of adsorption on χ₃-borophene is chemisorption for NO₂ and physisorption for SO₂ and H₂S. The mode of adsorption of CO and NH₃ on χ₃-borophene can be both physisorption and chemisorption, depending on the initially selected sites. Analyses of the charge transfer and density of states show that χ₃-borophene is selective toward the adsorption of harmful gases and that N and O atoms form covalent bonds when chemisorbed on the surface of χ₃-borophene. An interesting phenomenon is that when 8 Pmmn borophene adsorbs SO₂, the gas molecules are dismembered and strongly adsorb on the surface of 8 Pmmn borophene, which provides a way of generating O₂ while adsorbing harmful substances. Overall, the results of this work demonstrate the potential applications of borophene as a sensing material for harmful gas sensing or removal.