Electron transport in CO2 adsorbed ZnO nanowire: DFT study

Diethylbenzene and ethyltoluene adsorption studies on novel beta antimonide phosphorus nanosheets-a first-principle study

CONTEXT

In the present work, we examined the sensing behavior of monolayer beta antimonide phosphorus (β-SbP) sheets towards toxic volatile organic compounds (VOCs) namely, 1,2-diethylbenzene and 2-ethyltoluene using density functional theory (DFT) method. At first, using cohesive energy structural stability of the monolayer β-SbP is confirmed. The calculated energy band gap value of monolayer β-SbP is 2.168 eV, which is a semiconductor. Furthermore, the adsorption properties of 1,2-diethylbenzene and 2-ethyltoluene on β-SbP are studied through key factors, such as adsorption energy, Mulliken charge transfer, and relative band gap variation. The adsorption energy clearly shows (- 0.335 to - 0.903 eV) that both 1,2-diethylbenzene and 2-ethyltoluene are physisorbed on β-SbP monolayer. Besides, Mulliken charge transfer falls in the range of - 0.465 to 0.933 e; this information clearly shows that the β-SbP monolayer is a potential candidate for sensing 1,2-diethylbenzene and 2-ethyltoluene molecules.

METHODS

The structural firmness including electronic and adsorption properties of 1,2-diethylbenzene and 2-ethyltoluene on β-SbP monolayer are investigated with the support of the DFT method. Particularly, the hybrid generalized gradient approximation (hybrid GGA) along with Beck's three-parameter + Lee-Yang-Parr (B3LYP) exchange-correlation functional is utilized for relaxing the β-SbP monolayer. In the present work, all calculations are performed using the Quantum Atomistic Tool Kit (ATK) simulation package. In the present work, we utilized β-SbP monolayer as a chief sensing element to detect 1,2-diethylbenzene and 2-ethyltoluene to safeguard humans from toxic environments.

Novel chair graphene nanotubes as adsorbing medium for alanine and asparagine amino acids - A DFT outlook

Amino acids are required to make protein. The deficiency of amino acids leads to a lack of sleep and mood. Among various amino acids, we conducted the adsorption studies of alanine and asparagine amino acids on a novel one-dimensional material, chair graphene nanotube. The stability of the chair graphene nanotube is ensured with the negative formation energy, which is -6.490 eV/atom. The energy band gap of bare chair graphene nanotube is 1.022 eV, which possesses a semiconductor nature. The stable chair graphene nanotube is used as adsorbing material for alanine and asparagine amino acids. Besides, alanine and asparagine are physisorbed on chair graphene nanotubes that are confirmed by the range of adsorption energy from -0.107 eV to -0.718 eV. Upon adsorption of amino acids, the charge transfer outcome shows that chair graphene nanotubes behave as donors of electrons to alanine and asparagine. Further, the changes in the band gap of the chair graphene nanotube are noticed from the results of band structure and PDOS spectrum. The changes in the electron density also reveal the changes in the electronic properties of the chair graphene nanotube owing to alanine and asparagine sorption. The proposed report portrays the adsorption attributes of alanine and asparagine amino acids on 1D chair graphene nanotubes.

N-Nitrosamine sensing properties of novel penta-silicane nanosheets-a first-principles outlook

CONTEXT

N-Nitrosamine is one of the highly toxic carcinogenic compounds that are found almost in the entire environment. In the present work, novel penta-silicene (penta-Si) and penta-silicane (penta-HSi) are utilised to sense the N-nitrosamine in the air environment. Initially, structural firmness of penta-Si and penta-HSi is confirmed using cohesive energy. Subsequently, the electronic properties of penta-Si and penta-HSi are discussed with the aid of electronic band structure and projected density of states (PDOS) maps. The calculated band gap of penta-Si and penta-HSi is 0.251 eV and 3.117 eV, correspondingly. Mainly, the adsorption property of N-nitrosamine on the penta-Si and penta-HSi is studied based on adsorption energy, Mulliken population analysis along with relative energy gap changes. The computed adsorption energy range is in physisorption (- 0.101 to - 0.619 eV), which recommends that the proposed penta-Si and penta-HSi can be employed as a promising sensor to detect the N-nitrosamine in the air environment.

METHODS

The structural, electronic and adsorption behaviour of N-nitrosamine on penta-Si and penta-HSi are studied based on the density functional theory (DFT) approach. The hybrid generalized gradient approximation (GGA) with Becke's three-parameter (B3) + Lee-Yang-Parr (LYP) exchange correlation functional is used to optimise the base material. All calculations in the present work are carried out in Quantum-ATK-Atomistic Simulation Software.

First-principle study of Cu-, Ag-, and Au-decorated Si-doped carbon quantum dots (Si@CQD) for CO2 gas sensing efficacies

CONTEXT

Nanosensor materials for the trapping and sensing of CO₂ gas in the ecosystem were investigated herein to elucidate the adsorption, sensibility, selectivity, conductivity, and reactivity of silicon-doped carbon quantum dot (Si@CQD) decorated with Ag, Au, and Cu metals. The gas was studied in two configurations on its O and C sites. When the metal-decorated Si@CQD interacted with the CO₂ gas on the C adsorption site of the gas, there was a decrease in all the interactions with the lowest energy gap of 1.084 eV observed in CO₂_C_Cu_Si@CQD followed by CO₂_C_Au_Si@CQD which recorded a slightly higher energy gap of 1.094 eV, while CO₂_C_Ag_Si@CQD had an energy gap of 2.109 eV. On the O adsorption sites, a decrease was observed in CO₂_O_Au_Si@CQD which had the least energy gap of 1.140 eV, whereas there was a significant increase after adsorption in CO₂_O_Ag_Si@CQD and CO₂_O_Cu_Si@CQD with calculated ∆E values of 2.942 eV and 3.015 eV respectively. The adsorption energy alongside the basis set supposition error (BSSE) estimation reveals that CO₂_C_Au_Si@CQD, CO₂_C_Ag_Si@CQD, and CO₂_C_Cu_Si@CQD were weakly adsorbed, while chemisorption was present in the CO₂_O_Ag_Si@CQD, CO₂_O_Cu_Si@CQD, and CO₂_O_Au_Si@CQD interactions. Indeed, the adsorption of CO₂ on the different metal-decorated quantum dots affects the Fermi level (E_f) and the work function (Φ) of each of the decorated carbon quantum dots owed to their low E_f values and high ∆Φ% which shows that they can be a prospective work function-based sensor material.

METHODS

Electronic structure theory method based on first-principle density functional theory (DFT) computation at the B3LYP-GD3(BJ)/Def2-SVP level of theory was utilized through the use of the Gaussian 16 and GaussView 6.0.16 software packages. Post-processing computational code such as multi-wavefunction was employed for result analysis and visualization.

Interaction studies of propylene and butadiene on tricycle graphane nanosheet - A DFT outlook

In this research work, we employed a tricycle graphane nanosheet as a chemical sensor to monitor the toxic hydrocarbon molecules, namely propylene, and 1,3-butadiene, which are emitted from automobile industries. At first, the structural stability and dynamical permanency of tricycle graphane is ascertained based on cohesive energy and phonon-band-spectrum. Sequentially, the electronic properties of tricycle graphane are conferred with the results of the projected density of states spectrum and band structure. The computed band gap of tricycle graphane is 5.53 eV. Chiefly, the adsorption behaviour of target propylene and 1, 3-butadiene on tricycle graphane is explored by determining adsorption energy, relative band gap variation, and Mulliken population analysis. Furthermore, the range of adsorption energy magnitudes (-0.16 eV to -1.03 eV) demonstrates that the target hydrocarbon molecules are physically adsorbed on tricycle graphane material. The overall outcome endorses that the tricycle graphane can be utilised as a prominent sensor to sense the hydrocarbon molecules released from automobiles and monitor air pollutants.

Effects of Different Point Defects on the Electronic Properties of III–V Al0.5Ga0.5N Photocathode Nanowires

AlxGa1−xN nanowires are the key materials for next-generation ultraviolet (UV) detectors. However, such devices have a low quantum efficiency caused by the introduction of defects and impurities throughout the preparation process of nanowires. Herein, the effects of different interstitial defects and vacancy defects on the electronic structure of Al0.5Ga0.5N nanowires are investigated using density functional theory calculations. Our results successfully discovered that only the formation of an N interstitial defect is thermally stable. In addition, the introduction of different defects makes the different nanowires exhibit n-type or p-type characteristics. Additionally, different defects lead to a decrease in the conduction band minimum in band structures, which is the major cause for the decrease in work function and increase in electron affinity of Al0.5Ga0.5N nanowires. What is more, the calculation of the partial density of states also proved that the interstitial defects contribute to a re-hybridization of local electron orbitals and then cause more significant movement of the electron density. Our investigations provide theoretical guidance for the pursuit of higher-quantum-efficiency ultraviolet (UV) detectors.