Efficient sensing of sulfur containing toxic gases like H₂S and SO₂ is of the utmost importance due to the adverse effects of these noxious gases. Absence of an efficient 2D-based nanosensor capable of anchoring H₂S and SO₂ with feasible binding and an apparent variation in electronic properties upon the exposure of gas molecules has motivated us to explore the promise of a germanene nanosheet (Ge-NS) for this purpose. In the present study, we have performed a comprehensive computational investigation by means of DFT-based first-principles calculations to envisage the structural, electronic, and gas sensing properties of pristine, defected, and metal substituted Ge-NSs. Our initial screening has revealed that although interaction of SO₂ with pristine Ge-NSs is within the desirable range, H₂S binding however falls below the required values to guarantee an effective sensing. To improve the binding characteristics, we have considered the interactions between H₂S and SO₂ with defected and metal substituted Ge-NS. The systematic removals of Ge atoms from a reasonably large super cell lead to monovacancy, divacancies, and trivacancies in Ge-NS. Similarly, different transition metals like As, Co, Cu, Fe, Ga, Ge, Ni, and Zn have been substituted into the monolayer to realize substituted Ge-NS. Our van der Waals corrected DFT calculations have concluded that the vacancy and substitution defects not only improve the binding characteristics but also enhance the sensing propensity of both H₂S and SO₂. The total and projected density of states show significant variations in electronic properties of pristine and defected Ge-NSs before and after the exposure to the gases, which are essential in constituting a signal to be detected by the external circuit of the sensor. We strongly believe that our present work would not only advance the knowledge towards the application of Ge-NS-based sensing but also provide motivation for the synthesis of such efficient nanosensor for H₂S and SO₂ based on Ge monolayer.

中文翻译：

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含硫气体暴露下的变形和功能化基于锗烯的纳米传感器

由于这些有害气体的不利影响，有效检测含硫有毒气体（例如H ₂ S和SO ₂）至关重要。缺乏能够锚定H ₂ S和SO ₂的基于2D的高效纳米传感器具有可行性的结合以及气体分子暴露后电子性能的明显变化激发了我们探索锗纳米片（Ge-NS）的前景。在本研究中，我们已经通过基于DFT的第一性原理计算进行了全面的计算研究，以设想原始，缺陷和金属取代的Ge-NS的结构，电子和气体传感特性。我们的初步筛选显示，尽管SO ₂与原始Ge-NSs的相互作用在所需的范围内，但是H ₂ S的结合量却低于保证有效感测所需的值。为了改善结合特性，我们考虑了H ₂ S和SO之间的相互作用₂具有缺陷和金属取代的Ge-NS。从相当大的超级电池中系统去除Ge原子会导致Ge-NS中的单空位，双空位和三空位。类似地，已将不同的过渡金属（如As，Co，Cu，Fe，Ga，Ge，Ni和Zn）取代到单层中，以实现取代的Ge-NS。我们的范德华校正DFT计算得出的结论是，空位和取代缺陷不仅改善了结合特性，而且还增强了H ₂ S和SO ₂的感测倾向。。状态的总密度和投影密度显示了原始气体和有缺陷的Ge-NS的电子性质在暴露于气体之前和之后的显着变化，这对于构成要由传感器的外部电路检测的信号是必不可少的。我们坚信，我们目前的工作不仅会为基于Ge-NS的传感技术的应用提供知识，而且还将为基于Ge单层的H ₂ S和SO ₂的高效纳米传感器的合成提供动力。