Theoretical insights into the enhanced gas-sensing properties of Al-, P-, and AlP-doped BN nanosheets

<h4>Context</h4>Boron nitride nanosheets (BNNS) possess high thermal stability and large surface area; however, their inherently wide band gap and weak adsorption capability limit their effectiveness in gas-sensing and gas-storage applications. This study investigates the adsorption and sensing behavior of H₂, CH₄, and C₂H₅OH on pristine and doped BNNS, including Al-doped, P-doped, and AlP co-doped B₃₉N₃₉ systems, in order to evaluate how doping modification can overcome these intrinsic limitations. The results show that doping significantly narrows the energy gap of BNNS from 5.940 to 5.481, 5.771, and 5.242 eV for Al-, P-, and AlP-doped systems, respectively, thereby enhancing their sensing sensitivity. Pristine BNNS exhibits weak adsorption toward H₂, CH₄, and C₂H₅OH (-0.04, -0.27, and -2.95 kcal/mol), whereas Al-doped BNNS demonstrates markedly stronger interactions, especially for C₂H₅OH (-30.35 kcal/mol), indicating substantially improved sensing performance. Moreover, adsorption induces pronounced electronic structure changes in Al-doped and AlP co-doped BNNS, particularly in the presence of C₂H₅OH. These findings identify Al-doped BNNS as a highly promising material for H₂, CH₄, and C₂H₅OH sensing, while AlP co-doped BNNS is especially suitable for selective C₂H₅OH detection.<h4>Methods</h4>All DFT calculations were performed using the GAUSSIAN 09 program package. The structural, electronic, and adsorption properties were examined at the B3LYP/6-31G(d,p) level of theory. Natural Bond Orbital (NBO) analysis (version 3.1), as implemented in GAUSSIAN 09, was employed to examine the electronic structures and natural population analysis (NPA) charges, while the density of states (DOS) plots and molecular electrostatic potential (MEP) maps were generated using GaussSum 2.1.4 and MOLEKEL 4.3, respectively.