Achieving tunable adsorption selectivity and sensitivity of boridenes for gas detection by surface O-termination engineering

This study utilizes density functional theory (DFT) to explore the potential of using boridenes as gas-sensing materials for common organic and inorganic gases, including C₂H₂, C₂H₄, C₂H₆, C₄F₇N, CH₂O, CH₄, CO, CO₂, H₂, H₂O, N₂, NO, NO₂, O₂, SF₆ and SO₂. The adsorption atomic configurations and adsorption energies are calculated for all gas species in the Mo_4/3B₂-Mo_4/3B₂O₂ series, elucidating the change in the adsorption mechanism from chemisorption for the bare Mo_4/3B₂ monolayer to physisorption in the case of the Mo_4/3B₂O₂ monolayer and also manifesting the significance of O-terminations on the adsorption properties of boridenes for the considered gas species. In addition, the gas-sensing parameters, including recovery time, sensitivity and selectivity, are evaluated for Mo_4/3B₂ and Mo_4/3B₂O_<i>x</i> monolayers to demonstrate the tunable sensing performance of boridenes for target gas species by tailoring the surface functional groups. The results reveal that the bare Mo_4/3B₂ shows promising reusability and selectivity for detecting insulating gases (SF₆ and C₄F₇N) and their dissociated products (SO₂ and CO), while the presence of O-terminations greatly improves the recovery time (10^-8 s), sensitivity (100.0%) and selectivity (exclusive NO adsorption) of sensing NO pollutants in the air for the Mo_4/3B₂O₂ monolayer. Overall, this work is expected to benefit the research and development of gas-sensing materials based on boridenes for various application scenarios in the future experimental study.