Two-Dimensional Boron–Phosphorus Monolayer for Reversible NO₂ Gas Sensing

Abstract

We proposed a boron–phosphorus monolayer (BP-ML) and investigated its gas sensing properties by density functional theory including the van der Waals dispersion correction term. Electronic property analysis reveals that BP-ML is a semiconductor with an indirect bandgap of 0.54 eV. The adsorption energy calculations of nitrogen-containing gases (NCGs) such as N2O, NO2, NH3, and NO show that these gases are physisorbed on the BP-ML surface. Among the studied NCGs, the NO2 molecule exhibits a relatively higher charge (0.43 e), which further confirms a robust charge transfer and more reactivity with the BP-ML surface. The work function of BP-ML increases by NO2 adsorption from 4.75 to 5.13 eV, while it decreases with adsorption of other NCG molecules. We have noticed that NO2 shows a considerably short recovery time of 2.21 s at T = 300 K, strongly referring to the multitime reusable nanosensor characteristic of the BP-ML surface. Additionally, the transport properties of the BP surface for the real-time sensing application are investigated by using the nonequilibrium Green’s function (NEGF) approach. The current–voltage (I–V) characteristics indicate a significant (moderate) change along the armchair (zigzag) direction when the NO2 molecule is adsorbed on the BP-ML surface. These findings suggest that BP-ML surface-based sensors are highly sensitive for the detection of NO2 molecules with short recovery time.

Using Density Functional Theory to Correlate Charge Transport Properties with Gas Sensing by Organic Nanowires

“…Very interestingly, contrary to what we have discussed here for NNDMNH 2 , in particular, and OSC, in general, the change in the bond length, bond angle, etc. (geometric distortions) due to adsorption of gas molecules does not have any significant effect on the charge transport properties of the inorganic materials and, hence, on the device performance of inorganic sensors. − The two completely opposite scenarios for the sensitivity of charge transport properties in the details of the system environment, system geometry, etc. for inorganic and organic materials is due to the relative strengths of the electron–phonon interactions in these two classes of materials.…”

First-Principles Calculations of SiBi Nanosheets as Sensors for Oxygen-Containing Gases

“…Spin-polarized calculations were carried out in all the cases. The adsorption energy (E ads ) of the OCG molecules was calculated using ground state energy for the different orientation of the gas molecules including CO 2 , O 2 , SO 2 , and NO 2 at various locations on the monolayer surface and is defined as: − where, E (SiBi + OCGs) is the total relaxed energy of the gas adsorbed SiBi ML and E SiBi and E (OCGs) are the total energies of pristine SiBi ML and isolated gas molecules, respectively. Moreover, frequency calculation has been carried out to make sure that the obtained optimized lowest-energy structures are real local minima.…”

From fundamental to CO2 and COCl2 gas sensing properties of pristine and defective Si2BN monolayers

“…The binding locations of COCl 2 and CO 2 gas molecules, computed adsorption energy and adsorption distance when placed at different locations of pristine and defective Si 2 BN-ML structures are detailed in Table 3. It is interesting to notice that unlike most 2D materials, 61 the rumpling distance of Si 2 BN-ML structures in the presence of the COCl 2 and CO 2 gas molecules is mostly zero. The superior structural stability of Si 2 BN-ML structures upon adsorption of these gases make them suitable for the fabrication of reusable gas sensors for COCl 2 and CO 2 .…”

“…The changes in the electrical conductivity are related to the charge transfer between the gas molecules and the Si 2 BN-ML. Besides, an efficient gas sensing performance depends on the quantifiable variations in the electrical conductivity 38,[61][62][63] of Si 2 BN-ML after the adsorption of COCl 2 and CO 2 molecules. In general, the adsorption of COCl 2 and CO 2 molecules on the Si 2 BN-ML can either increase or decrease the conductivity, depending on the rate of charge transfer between the Si 2 BN-ML and these target molecules.…”