MoTeSe/InN heterostructures for gas sensors: a first-principles study

Two-dimensional van der Waals heterojunctions can significantly boost gas-sensing performance through interfacial synergy, surpassing the limits of individual constituents. Based on first-principles calculations, this study systematically explores the potential of a vertical heterojunction composed of novel Janus MoTeSe and InN for gas-sensing applications. Binding-energy calculations and AIMD simulations identify AB-MoIn-stacked MoTeSe/InN as the most stable configuration, and the adsorption behavior and sensing mechanism of the heterojunction toward Cl₂, NO₂, NH₃, NO, SO₂, and H₂S are investigated comprehensively. The results reveal that the heterojunction markedly enhances adsorption of Cl₂, NO₂, NO, and H₂S, with adsorption energies of -0.880 eV and -0.961 eV for Cl₂ and NO₂, respectively, accompanied by substantial charge transfer. Electronic-structure analysis elucidates the key sensing mechanisms: adsorption of NO₂ (T In site) and NO metallizes the system, greatly increasing electrical conductivity; adsorption of Cl₂ (TN site) and SO₂ increases the bandgap by approximately 47.3 % and 49.4 %, respectively; notably, NO₂ adsorption on the Te site also induces magnetism. Further evaluation of sensitivity and recovery time indicates that the heterojunction exhibits both high sensitivity and good reversibility toward NO₂ and Cl₂—for example, the room-temperature recovery time for NO₂ on the Te site is only 0.36 ms. This work clarifies the atomic-scale gas-sensing mechanism of MoTeSe/InN heterostructures, especially for Cl₂ and NO₂, and provides a solid theoretical basis for their application as high-performance, recyclable gas-sensor candidates.