Adsorption sensitivity of pristine and Al- or Si-doped boron nitride nanoflake to COCl2: a DFT study

First-principles investigations of As-doped tetragonal boron nitride nanosheets for toxic gas sensing applications

Pristine and arsenic-doped tetragonal boron nitride nanosheets (BNNS and As-BNNS) have been reported as potential candidates for toxic gas sensing applications. We have investigated the adsorption behavior of BNNS and As-BNNS for CO2, H2S, and SO3 gas molecules using first-principles density functional theory (DFT). Both BNNS and As-BNNS possess negative cohesive energies of -8.47 and -8.22 eV, respectively, which indicates that both sheets are energetically stable. Successful adsorption is inferred from the negative adsorption energy and structural deformation in the vicinity of the adsorbent and adsorbate. As-doping results in a significant increase in adsorption energies from -0.094, -0.175, and -0.462 eV to -2.748, -2.637, and 3.057 eV for CO2, H2S and SO3 gases, respectively. Due to gas adsorption, the electronic bandgap in As-BNNS varies by approximately 32% compared to a maximum of 24% in BNNS. A notable fluctuation in the energy gap and electrical conductivity is seen, with ambient temperature being the point of maximal sensitivity. For SO3, the maximum charge transfer during adsorption in BNNS and As-BNNS is determined to be 0.08|e| and 0.25|e|, respectively. Due to the interaction with gases, all structures exhibit an extremely high absorption coefficient on the order of 104 cm-1 with minimal peak shifting. Additionally, doping an As atom on BNNS' surface remarkably improved its ability to sense CO2, H2S, and SO3 gasses.

Synthesis and modification of boron nitride nanomaterials for gas sensors: from theory to application

Boron nitride (BN) has gradually emerged as a significant focus of research due to its unique physical and chemical properties. Over the past few years, substantial advancements have been achieved in the domains of gas adsorption and sensing, driven by improvements in modification technology and a deeper understanding of gas sensing mechanisms. BN-based nanomaterials have been instrumental in these advancements. The application of some properties of BN in the fabrication of gas sensing components is anticipated to lead to new breakthroughs. Furthermore, BN is projected to become one of the most promising materials for high-performance gas sensors, owing to its high thermal stability, chemical stability, and exceptional mechanical properties. While numerous review articles have been published regarding BN, primarily focusing on its synthesis, properties, and functionalities, few have made significant contributions to the realm of gas adsorption and detection through theoretical calculations and practical applications. This review comprehensively examines the integration of BN with various gas adsorption and sensing techniques, covering aspects such as model development, theoretical computations, material synthesis, and real-world applications. These methods provide valuable insights into the potential of BN for gas sensing applications. Furthermore, the paper discusses the challenges encountered in utilizing BN-based gas sensors and offers recommendations for overcoming these challenges. Finally, the future prospects for the advancement of BN-based gas sensors are considered, highlighting new possibilities and areas for improvement within this field.

Ab Initio Study of the Graphyne-like γ-SiC Nanoflake for Toxic Gas-Sensing Applications

This study focuses on the geometrical, electronic, and optical properties of the γ-graphyne-like novel γ-SiC nanoflake of the γ-silicon carbide (SiC) monolayer using density functional theory calculations. γ-SiC was revealed to be a stable semiconducting nanoflake confirmed by a negative cohesive energy, real vibrational frequencies, and a 1.749 eV energy gap. The adsorption of COCl2, HCN, PH3, AsH3, CNCl, and C2N2 toxic gases on the γ-SiC nanoflake is also studied, which revealed an attractive gas-nanoflake interaction with the adsorption energy ranging from -0.21 to -0.38 eV. The adsorption results in a significant charge transfer between gas-adsorbent complexes. A significant variation in the energy gap and electrical conductivity was observed due to gas adsorption. γ-SiC showed maximum sensitivity at room temperature for CNCl gas. The entire process of adsorption is exothermic and thermodynamically stable. γ-SiC showed a high absorption coefficient over 104 orders with a significant variation in the absorption peak intensity and blue peak shifting. According to the quantum theory and reduced density gradient analysis, all of the gases are physisorbed on the γ-SiC nanoflake due to van der Waals interactions. The obtained results signify the usability of γ-SiC as a potential toxic gas sensor.

From Fundamental to CO2 and COCl2 Gas Sensing Properties of Pristine and Defective Si2BN Monolayer

The capability of Si2BN monolayer (Si2BN-ML) in sensing CO2 and COCl2 molecules is investigated by analyzing the structural, electronic, mechanical and gas sensing properties of defect-free and defective Si2BN-ML. Electronic...

A Theoretical Framework of Zinc-Decorated Inorganic Mg12O12 Nanoclusters for Efficient COCl2 Adsorption: A Step Forward toward the Development of COCl2 Sensing Materials

Gas sensors are widely explored due to their remarkable detection efficiency for pollutants. Phosgene is a toxic gas and its high concentration in the environment causes some serious health problems like swollen throat, a change in voice, late response of nervous systems, and many more. Therefore, the development of sensors for quick monitoring of COCl2 in the environment is the need of the time. In this aspect, we have explored the adsorption behavior of late transition metal-decorated Mg12O12 nanoclusters for COCl2. Density functional theory at the B3LYP/6-31G(d,p) level is used for optimization, frontier molecular orbital analysis, dipole moment, natural bonding orbitals, bond lengths, adsorption energies, and global reactivity descriptor analysis. Decoration of Zn on pure Mg12O12 delivered two geometries named as Y1 and Y2 with adsorption energy values of -388.91 and -403.11 kJ/mol, respectively. Adsorption of COCl2 on pure Mg12O12 also delivered two geometries (X1 and X2) with different orientations of COCl2. The computed adsorption energy values of X1 and X2 are -44.92 and -71.32 kJ/mol. However, adsorption of COCl2 on Zn-decorated Mg12O12 offered two geometries named as Z1 and Z2 with adsorption energy values of -455.22 and -419.04 kJ/mol, respectively. These adsorption energy values suggested that Zn decoration significantly enhances the adsorption capability of COCl2 gas. Further, the narrow band gap and large dipole moment values of COCl2-adsorbed Zn-decorated Mg12O12 nanoclusters suggested that designed systems are efficient candidates for COCl2 adsorption. Global reactivity indices unveil the great natural stability and least reactivity of designed systems. Results of all analyses suggested that Zn-decorated Mg12O12 nanoclusters are efficient aspirants for the development of high-performance COCl2 sensing materials.

Comparative Study of Phosgene Gas Sensing Using Carbon and Boron Nitride Nanomaterials-A DFT Approach

Phosgene (COCl₂), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl₂. The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl₂ molecule adsorbed spontaneously on the Fullerene or nanocages and endothermically on the pristine zigzag nanotubes. Using the magnitude of the bandgap modulation, the order of suitability of the different nanomaterials was established as follows: PBN60 (0.19%) < PC70 (1.39%) < PC60 (1.77%) < PBNNT (27.64%) < PCNT (65.29%) < PBN70 (134.12%). Since the desired criterion for the design of an electronic device is increased conductivity after adsorption due to the resulting low power consumption, PC60 was found to be most suitable because of its power consumption as it had the largest decrease of 1.77% of the bandgap.

The adsorption of chlorofluoromethane on pristine, and Al- and Ga-doped boron nitride nanosheets: a DFT, NBO, and QTAIM study

In the present investigation, the feasibility of detecting the chlorofluoromethane (CFM) gas molecule onto the outer surface of pristine single layer boron nitride nanosheet (BNNS), as well as its aluminum (Al)- and gallium (Ga)-doped structures, was carefully evaluated. For achieving this goal, a density functional theory level of study using the Perdew, Burke, and Ernzerhof exchange-correlation (PBEPBE) functional together with a 6-311G(d) basis set has been used. Subsequently, the B3LYP, CAM-B3LYP, wB97XD, and M062X functionals with a 6-311G(d) basis set were also employed to consider the single-point energies. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) were implemented by using the B3LYP-D3/6-311G(d) method, and the results were compatible with the electronic properties. In this regard, the total density of states (TDOSs), the Wiberg bond index (WBI), natural charge, natural electron configuration, donor-acceptor natural bond orbital interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses denote that by adsorbing of the gas molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong chemical adsorption. Among the doped nanosheets, Ga-doped nanosheet has very high adsorption energy compared with other elements (i.e., Ga-doped > Al-doped > pristine). Generally, it was revealed that the sensitivity of the adsorption will be increased when the gas molecule interacts with decorated nanosheets and decrease the HOMO-LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanosensors to detect CFM gas. Graphical abstract.