Arsenene Nanotube as a Chemical Sensor to Detect the Presence of Explosive Vapors: A First-Principles Insight

Atomically thin-layered WS2based resistive sensors for detection of CO and NO2at room temperature

The number of layers present in a two-dimensional (2D) nanomaterial plays a critical role in applications that involve surface interaction, for example, gas sensing. This paper reports the synthesis of 2D WS2nanoflakes using the facile liquid exfoliation technique. The nanoflakes were exfoliated using bath sonication (BS-WS2) and probe sonication (PS-WS2). The thickness of the BS-WS2was found to range between 70 and 200 nm, and that of PS-WS2varied from 0.6 to 80 nm, indicating the presence of single to few layers of WS2when characterized using atomic force microscope. All the WS2samples were thoroughly characterized using electron microscopes, x-ray diffractometer, Raman spectroscopy, UV-Visible spectroscopy, Fourier transform infrared spectroscope, and thermogravimetric analyser. Both the nanostructured samples were exposed to 2 ppm of NO2at room temperature. Interestingly, BS-WS2which comprises of a greater number of WS2layers exhibited -14.2% response as against -3.4% response of PS-WS2, the atomically thin sample. The BS-WS2sample was found to be highly selective towards NO2but was slower (with incomplete recovery) as compared to PS-WS2. The PS-WS2sample was observed to exhibit -11.9% to -27.4% response to 2-10 ppm of CO and -3.4%-35.2% response to 2-10 ppm of NO2at room temperature, thereby exhibiting the potential to detect two gases simultaneously. These gases could be accurately predicted and quantified if the response times of the PS-WS2sample were considered. The atomically thin WS2-based sensor exhibited a limit of detection of 131 and 81 ppb for CO and NO2, respectively.

Sorption studies of sulfadimethoxine and tetracycline molecules on β-antimonene nanotube - A first-principles insight

We ascertained the structural firmness of β-antimonene nanotube and studied the adsorption behaviour of sulfadimethoxine (SM) and tetracycline (TC) molecules on the base substrate using density functional theory (DFT) with B86LYP-D3 level of theory. Significantly, β-antimonene nanotube displays a semiconducting character with an energy band-gap of 0.263 eV. The three dissimilar preferential adsorption sites namely, bride-, hollow-, tube-inner site of SM and TC molecules on β-antimonene nanotube were investigated using average band gap changes, Bader charge transfer along with adsorption energy. Further, the calculated adsorption energy for preferential adsorption sites is noticed to be in the scope of -0.813 eV to -3.752 eV signifying to physisorption and chemisorption form of interaction on β-antimonene nanotube. The inclusive outcome recommends that β-antimonene nanotube can be deployed as a chemi-resistive sensor to sense and remove SM and TC molecules from the contaminated aqueous medium.

Investigation on adsorption features of nitroglycerin on novel red tricycle arsenene nanosheet - A first-principles study

The chemo sensing features of red tricycle arsenene nanosheet (RTANS), a monolayer obtained from allotropes of arsenic is employed in sensing the hazardous vapor nitroglycerin (NG) based on the first-principles investigation. The computations are carried out with the ATK-VNL package. The stability of the RTANS is validated by its formation energy, which is calculated as -4.171 eV/atom. The adsorption energy, Bader charge transfer, energy gap, and its variation after adsorption are the essential parameters that hold up the discussion on RTANS base material as an efficient chemical sensor. Moreover, the target vapor NG is physisorbed on RTANS. Besides, all the essential parameters have been investigated for the interaction of NG on RTANS. The comprehensive study reveals that RTANS can be used as a chemical sensor for the detection of nitroglycerin vapors.

Structural transition induced by compression and stretching of puckered arsenene nanotubes

The stretching and compression effects on puckered arsenene nanotubes (AsNTs) are investigated by using density functional calculations. The atomic arrangement determines the nanotube properties and relative stability; therefore, zigzag, chiral, and armchair present different properties. Since the AsNT properties depend on the diameter, three cases are considered: (a) (0, 9) and (9, 0), (b) (0, 14) and (14, 0), and (c) (0, 19) and (19, 0) NTs. For all calculated parameters of the smallest NTs, it is found that the armchair (0, 9) nanotube is always more stable than the zigzag (9, 0) nanotube. On the other hand, for the two largest NTs, a structural transition from armchair to zigzag is found upon stretching. Phase transitions are of great interest, in part because they result in changes of the properties of the material under study, changes that can be used in many technologies. To our knowledge, this is the first time that a structural transition in a puckered nanotube has been predicted. Our results show that the electronic band gap of the AsNTs can be modulated by increasing or decreasing the axial lattice parameter. It is also found that semiconductor NTs are more stable than metallic NTs.