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低维材料表面的有毒气体吸附一直是分子传感器领域的研究热点. 最近的新型正交相二维BN单层半导体材料引起了学者的广泛关注. 基于第一性原理计算, 本文研究了有毒气体分子(CO, H 2S, NH 3, NO, NO 2和SO 2)在二维正交相BN单层表面的吸附特性. 吸附能计算表明, 正交相BN材料对所有气体的吸附均是能量有利的放热过程.NO 2和NH 3为化学吸附, 其他体系均为物理吸附, 且NO吸附后体系具有自旋极化的电子能带结构. 态密度计算结果显示, NO 2和SO 2的吸附对费米能级附近的电子占据有显著影响.NO 2吸附后, 体系的功函数和电子结构特性均明显改变, 表明BN单层半导体材料对NO 2分子具有良好的吸附选择性和探测灵敏度. 采用第一性原理结合非平衡格林函数方法计算了纳米电子器件的输运性能. 在1 V偏压下, NO 2分子的吸附可使体系电流增大到6500 nA, 显著增强了BN单层半导体器件的电输运性能, 因此二维BN单层对NO 2气体吸附具有优异的探测敏感度. 此外, 轴向应力能够有效调控体系的吸附性能. 研究表明, 正交相BN单层材料对有毒气体具有优异的吸附性能, 在新型有毒气体传感探测器件领域有较大的应用潜力.The adsorption properties of toxic gases on the surface of low-dimensional nanomaterials are a research hot topic and key issue for developing semiconductor sensors to detect toxic gas molecules. Recently, a novel orthorhombic BN monolayer has attracted extensive attention from researchers. Using first principles calculations, we investigate the adsorption properties of typical toxic gas molecules, such as CO, H 2S, NH 3, NO, NO 2, and SO 2molecules, on the surface of two-dimensional (2D) orthorhombic BN monolayer adsorption. The calculated adsorption energy show that the adsorptions of the above six molecules on the surface of BN monolayer are energy-favorable exothermic processes. It is found that NO 2and NH 3molecules are of chemical adsorption, while other systems are of physical adsorption, and NO adsorbing system exhibits a spin-polarized electronic band structure. The calculated density of states reveals that the adsorption of NO molecule and SO 2molecule have significant influences on the electronic structure near the Fermi level. Moreover, the adsorption of the NO 2molecule on the substrate exhibits remarkable variation of the work function, suggesting that the o-BN monolayer possesses excellent selectivity and sensitivity to NO 2molecule. In addition, we use first principles combined with non-equilibrium Green’s function to simulate the electrical transport properties of monolayered o-BN semiconductor based nanodevice with adsorption of typical toxic gas molecules. The I-V bcurve shows that the current through the nanodevice is 6500 nA for the NO 2molecule adsorbing system under 1 V bias voltage. The calculation results reveal that the adsorption of NO 2molecule on the o-BN monolayer can significantly enhance its electrical transport performance, and the o-BN monolayer possesses excellent sensitivity and selectivity to the NO 2gas molecule. The work function and the charge transfer can be effectively manipulated by tensile strain, indicating its potential application in anisotropic electronics. Our results indicate that the o-BN monolayer has excellent adsorption performance to toxic gases, showing its practical application in capturing toxic gas molecules as a gas sensor in future.
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Keywords:
- adsorption/
- orthorhombic BN/
- first-principles/
- electrical transport/
- gas sensor
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$ {E}_{{\mathrm{a}}{\mathrm{d}}} $/eV d/Å Q/e CO –0.151 2.999 0.032 H2S –0.186 2.488 0.014 NH3 –0.222 1.762 –0.102 NO –0.258 2.284 0.133 NO2 –0.893 1.679 0.780 SO2 –0.380 2.922 0.165 
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Gas
moleculeTemperature/K 300 400 500 600 CO 3.44×10–11 7.99×10–12 3.33×10–12 1.85×10–12 H2S 1.33×10–10 2.20×10–11 7.49×10–12 3.65×10–12 NH3 5.36×10–10 6.26×10–11 1.73×10–11 7.32×10–12 NO 2.16×10–9 1.78×10–10 3.98×10–11 1.47×10–11 NO2 100.13 0.02 1.00×10–4 3.16×10–6 SO2 2.42×10–7 6.13×10–9 6.76×10–10 1.55×10–10 下载:
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Adsorbed gas $ \varPhi $/eV $ {{\Delta }}\varPhi $/eV S/% CO 4.141 0.032 0.78 H2S 4.465 0.356 8.66 NH3 4.203 0.094 2.29 NO 4.103 –0.006 0.15 NO2 5.366 1.257 30.59 SO2 4.599 0.450 10.95 下载:
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