The adsorption of various environmental gas molecules, including H₂, N₂, CO, CO₂, O₂, NO, NO₂, SO₂ H₂O, H₂S, NH₃ and CH₄, on the surface of the recently synthesized two dimensional MoSi₂N₄ (MSN) monolayer has been investigated by means of spin-polarized first-principles calculations. The most stable adsorption configuration, adsorption energy, and charge transfer have been computed. Due to the weak interaction between molecules studied with the MSN monolayer surface, the adsorption energy is small and does not yield any significant distortion of the MSN lattice, i.e., the interaction between the molecules and MSN monolayer surface is physisorption. We find that all molecules are physisorbed on the MSM surface with small charge transfer, acting as either charge acceptors or donors. The MSN monolayer is a semiconductor with an indirect band gap of 1.79 eV. Our theoretical estimations reveal that upon adsorption of H₂, N₂, CO, CO₂, NO, H₂O, H₂S, NH₃ and CH₄ molecules, the semiconducting character of MSN monolayer is preserved and the band gap value is decreased to $~$1.5 eV. However, the electronic properties of the MSN monolayer can be significantly altered by adsorption of O₂, NO and SO₂, and a spin polarization with magnetic moments of 2, 1, 2 ${\mu }_B$, respectively, can be introduced. Furthermore, we demonstrate that the band gap and the magnetic moment of adsorbed MSN monolayer can be significantly modulated by the concentration of NO and SO₂ molecules. As the concentration of NO₂ molecule increases, the magnetic moment increase from 1 ${\mu }_B$ to 2 and 3 ${\mu }_B$. In the case of the SO₂ molecule with increasing of concentration, the band gap decreases from 1.2 eV to 1.1 and 0.9 eV. Obviously, our theoretical studies indicate that MSN monolayer-based sensor has a high application potential for O₂, NO, NO₂ and SO₂ detection.

各种环境气体分子，包括H ₂、N ₂、CO、CO ₂、O ₂、NO、NO ₂、SO ₂ H ₂ O、H ₂ S、NH ₃和CH ₄，在最近的表面上的吸附合成二维 MoSi ₂ N ₄(MSN) 单层已经通过自旋极化第一性原理计算进行了研究。已计算出最稳定的吸附构型、吸附能和电荷转移。由于所研究的分子与 MSN 单层表面的相互作用较弱，吸附能很小并且不会产生任何明显的 MSN 晶格畸变，即分子与 MSN 单层表面之间的相互作用是物理吸附。我们发现所有分子都以小的电荷转移物理吸附在 MSM 表面，充当电荷受体或供体。MSN 单层是一种间接带隙为 1.79 eV 的半导体。我们的理论估计表明，在吸附 H ₂、N ₂、CO、CO ₂、NO、H₂ O、H ₂ S、NH ₃和CH ₄分子，保留了MSN单层的半导体特性，带隙值降低到$~$1.5 电子伏特。然而，MSN 单层的电子特性可以通过吸附 O ₂、NO 和 SO ₂以及磁矩为 2, 1, 2 的自旋极化而显着改变${\mu }_{乙}$，分别可以介绍。此外，我们证明了吸附的 MSN 单层的带隙和磁矩可以通过 NO 和 SO ₂分子的浓度显着调节。随着 NO ₂分子浓度的增加，磁矩从 1${\mu }_{乙}$ 到 2 和 3 ${\mu }_{乙}$. 在 SO ₂分子随着浓度增加的情况下，带隙从 1.2 eV 减小到 1.1 和 0.9 eV。显然，我们的理论研究表明，基于MSN 单层的传感器在O ₂、NO、NO ₂和SO ₂检测方面具有很高的应用潜力。