First-principles investigation on detection of phosgene gas molecules using phosphorene nanosheet device

Suitability of chlorobenzene-based single-electron transistor as HCN, AsH3, and COCl2 sensor

A density functional theory (DFT)-based first principle approach has been employed to investigate the suitability of chlorobenzene-based single-electron transistor (SET) for the detection of few toxic gases such as hydrogen cyanide, arsine, and phosgene. The adsorption aspect of toxic gas molecules on the chlorobenzene with different orientations has been analyzed. The attributes such as charge density, molecular energy spectrum, density of states, and Mulliken population have been computed to scrutinize the effect of gas molecules on the surface of chlorobenzene. The sensing mechanism of adsorbate (toxic gases) with the adsorbent (chlorobenzene) has been authenticated in a single-electron transistor (SET) environment through total energy vs. gate voltage plot and charge stability diagram. The recovery time of the chlorobenzene-based SET gas sensor on the adsorption of HCN, AsH₃, and COCl₂ has been computed as 1.93 ns, 0.45 ns, and 36.31 ns, respectively. Based on these findings, it is interesting to see that the COCl₂ gas molecule shows strong physical adsorption with the most significant adsorption distance (3.629 Å) with chlorobenzene, while AsH₃-adsorbed chlorobenzene SET displays a low recovery time in comparison with other considered gases. The present analysis confirms a significantly better range of detection and improved recovery time using chlorobenzene-based single-electron transistor.

Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe2: Germanene-Enabled Vapor Sensor

Two-dimensional germanene has been recently explored for applications in sensing, catalysis, and energy storage. The potential of this van der Waals material lies in its optoelectronic and chemical properties. However, pure free-standing germanene cannot be found in nature, and the synthesis methods are hindering the potentially fascinating properties of germanene. Herein, we report a single-step synthesis of few-layer germanene by electrochemical exfoliation in a nonaqueous environment. As a result of simultaneous decalcification and intercalation of the electrolyte's active ions, we achieved low-level hydrogenation of germanene that occurs at the edges of the material. The obtained edge-hydrogenated germanene flakes have a lateral size of several micrometers and possess a cubic structure. We have pioneered the potential application of edge-hydrogenated germanene for vapor sensing and demonstrated its specific sensitivity to methanol and ethanol. Furthermore, we have shown a selective behavior of the germanene-based sensor that appears to increase the electrical resistance in the vapors where methanol prevails. We anticipate that these results can provide an approach for emerging layered materials with the potential utility in advanced gas sensing.

Adsorption and dissociation of COCl2 on the rutile TiO2(110) surfaces: a systematic first-principles study

The adsorption and dissociation of phosgene (COCl₂) molecules on three kinds of rutile TiO₂(110) surfaces (stoichiometric: TiO₂-Sto; oxygen defective: TiO₂-Ov; and substoichiometric: TiO_1.875) were investigated based on density functional theory calculations. The nature of interactions between the COCl₂ molecule and rutile TiO₂(110) surfaces with different degrees of reduction was researched by the analysis of geometries, electron density difference, adsorption energies and density of states (DOS). Computational results show that COCl₂ indicates instability and will dissociate directly without the presence of transition states on a substoichiometric TiO_1.875(110) surface. The adsorption and dissociation behavior of COCl₂ on the rutile surface is not only helpful in providing theoretical support for the clean and efficient degradation of COCl₂, but also helpful in elucidating the role of COCl₂ as an intermediate product in the carbochlorination of titanium ore.

Interaction studies of kidney biomarker volatiles on black phosphorene nanoring: A first-principles investigation

We report the electronic properties of black phosphorene nanoring (BPN) and adsorption behavior of chronic kidney disease biomarker vapors on BPN. The designed BPN is stable, which is ensured by the formation energy with a value of -3.857eV/atom. The band gap of BPN is recorded as 0.716eV showing the semiconductor property. The prominent kidney disease biomarker vapors, namely isoprene, pentanal, hexanal, heptanal are allowed to interact on BPN and studied based on adsorption property on BPN. Based on charge transfer, energy band gap variation and adsorption energy, we studied the adsorption behavior of BPN towards kidney disease biomarkers. Our findings show that BPN can be used to detect the presence of kidney biomarkers.

Remarkable improvement in phosgene detection with a defect-engineered phosphorene sensor: first-principles calculations

This paper has addressed the monitoring of phosgene (COCl2) via pristine (BP) and defective (DP) phosphorene monolayer nanosensors at the HSE06/TZVP level of theory. The most stable structures of phosgene preferred planar configurations, which were parallel to the surface. Overall, the defect-engineered nanosensor was highly sensitive (726% gas sensitivity) and reusable (0.31 ns recovery time at room temperature) for phosgene detection. DP was a better work-function sensor of COCl2 compared to BP. The gas response was enhanced by a factor of 54 with vacancy doping. Furthermore, the selectivity of the defect-engineered phosphorene was predicted to be extremely high in both dry and humid air. Such improvements open new opportunities for the rational design of novel and reusable 2D sensors for the detection of toxic COCl2 molecules.

Exploring adsorption behavior of ethylene dichloride and dibromide vapors on blue phosphorene nanosheets: A first-principles acumens

The interrelation of toxic vapors ethylene dichloride (EDC) and ethylene dibromide (EDB) with the sensory base material blue phosphorene nanosheet (BLPNS) is studied using ab-initio method. The formational stability of BLPNS is ensured by the negative value of formation energy. Prior to the adsorption studies, we calculated the formation energy of BLPNS to ensure its stability, which is calculated to be -5.194eV/atom and found stable. The main motive behind the present work is to detect these toxic vapors using BLPNS. The intercommunication between the targeted vapors and the base material has been analyzed using the aid of adsorption energy, Bader charge transfer, energy band gap, and variation of band gap along with energy bands and DOS spectrum. The energy gap of isolated BLPNS is observed to be 1.621eV. However, the adsorption of EDC and EDB modulates the energy gap of BLPNS. The nature of assimilation is noticed to be of physisorption, which facilitates desorption of EDC and EDB molecules much easier. The successful outcome of the present research validates that BLPNS can be deployed as a prominent sensor for detection of EDC and EDB effectively.