Abstract The sensing properties of GeP monolayer to small gas molecule (CO, CO2, O2, H2O, NH3, NO and NO2) have been investigated by performing first-principle calculations. Based on calculated adsorption distance, adsorption energy and charge transfer, we find that GeP monolayer is the most sensitive to NO2 and NO molecules, and all gas molecules act as acceptors to gain electrons from GeP monolayer. The adsorption energy of NO2 is smaller than that of NO molecule, which implies that NO2 is more easily desorbed from GeP. And different work function changes also indicate the possibility to identify NO2 and NO in an oxygen-free environment. Moreover, we apply uniaxial and biaxial strains to GeP monolayer and find that a small biaxial compressive strain can effectively enhance the sensitivity of work function type sensor based GeP to NO2 molecule without increasing recovery time. We also discuss the effect of external vertical electric field on the adsorption performance of NO2 molecule. The negative electric field can significantly increase the adsorption strength, charge transfer and work function change of NO2-GeP system. Our results indicate that GeP monolayer is a potential candidate for NO2 gas sensor.

中文翻译：

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应用应变和电场对小分子在 GeP 单层上的可调吸附行为

摘要 通过第一性原理计算研究了 GeP 单分子层对小气体分子（CO、CO2、O2、H2O、NH3、NO 和 NO2）的传感特性。根据计算的吸附距离、吸附能和电荷转移，我们发现 GeP 单层对 NO2 和 NO 分子最敏感，所有气体分子都作为受体从 GeP 单层获得电子。NO2 的吸附能小于 NO 分子的吸附能，这意味着 NO2 更容易从 GeP 中解吸。并且不同的功函数变化也表明在无氧环境中识别 NO2 和 NO 的可能性。而且，我们将单轴和双轴应变应用于 GeP 单层，发现小的双轴压缩应变可以有效提高基于功函数型传感器的 GeP 对 NO2 分子的灵敏度，而不会增加恢复时间。我们还讨论了外部垂直电场对 NO2 分子吸附性能的影响。负电场可以显着增加NO2-GeP体系的吸附强度、电荷转移和功函数变化。我们的结果表明 GeP 单层是 NO2 气体传感器的潜在候选者。