Study on the adsorption properties of O3, SO2, and SO3 on B-doped graphene using DFT calculations

Phosphorus-doped T-graphene nanocapsule toward O3 and SO2 gas sensing: a DFT and QTAIM analysis

Tetragonal graphene nano-capsule (TGC), a novel stable carbon allotrope of sp2 hybridization is designed and doped with phosphorus (P) to study the O3 and SO2 gas sensitivity via density functional theory calculation. Real frequencies verified the natural existence of both TGC and P-doped TGC (PTGC). Both TGC and PTGC suffer structural deformations due to interaction with O3 and SO2 gases. The amount of charge transfer from the adsorbent to the gas molecule is significantly greater for O3 adsorption than SO2 adsorption. The adsorption energies for TGC + O3 and PTGC + O3 complexes are - 3.46 and - 4.34 eV respectively, whereas for TGC + SO2 and PTGC + SO2 complexes the value decreased to - 0.29 and - 0.30 eV respectively. The dissociation of O3 is observed via interaction with PTGC. A significant variation in electronic energy gap and conductivity results from gas adsorption which can provide efficient electrical responses via gas adsorption. The blue/red shift in the optical response proved to be a way of detecting the types of adsorbed gases. The adsorption of O3 is exothermic and spontaneous whereas the adsorption of SO2 is endothermic and non-spontaneous. The negative change in entropy verifies the thermodynamic stability of all the complexes. QTAIM analysis reveals strong covalent or partial covalent interactions between absorbent and adsorbate. The significant variation in electrical and optical response with optimal adsorbent-gas interaction strength makes both TGC and PTGC promising candidates for O3 and SO2 sensing.

Electron regulation and gas-sensitivity analysis of hBN-Graphene lateral heterojunctions--First principle study

In this paper, the first-principle calculations of the lateral heterojunction model synthesized by hBN-Graphene were carried out, and it was found that the bandgap of graphene varied with the change in the proportion of hBN, and the bandgap was best regulated with a bandgap of 1.177 eV when the proportion of hBN was 66.67 %. At this time, the adsorption structures of HCN, CO, NH3, and Cl2 were established and energy band calculations were performed on the hBN and Graphene portions of the hBN-Graphene lateral heterojunctions, respectively, and it was found that the adsorption of Cl2 resulted in a significant change in the band gap, which showed a very high electrical sensitivity. To further investigate the adsorption mechanism of Cl2 on the surface of hBN-Graphene lateral heterojunction, the energy band structure, PDOS, charge transfer, adsorption energy, and recovery time of each stabilized adsorption site of Cl2 on the surface of hBN-Graphene lateral heterojunction were calculated. The results show that the adsorption of Cl2 on the surface of hBN-Graphene lateral heterojunction is a stable chemisorption, and the band gap of C-Top1 increases to 1.274 eV, and the band gaps of C-Top3, N-Top1, and N-Top2 decrease to 0.684 eV, 0.376 eV, and 0.398 eV, respectively, and the changes of band gaps are significant and easy to be electrically detection. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s-2.59 s in visible light and in the temperature interval of 273 K-283 K. The recovery time of Cl2 on the surface of hBN-Graphene lateral heterojunction was 7.36 s-2.59 s in visible light and in the temperature interval of 273 K-283 K. These findings have implications for the research and application of graphene-based Cl2 gas sensors.

Adsorption of sulfur-containing contaminant gases by pristine, Cr and Mo doped NbS2monolayers based on density functional theory

The adsorption and sensor performance of hazardous gases containing sulfur (SO2, H2S and SO3) on pristine, Cr and Mo doped NbS2monolayers (Cr-NbS2and Mo-NbS2) were investigated in detail based on density functional theory. The comparative analysis of the parameters such as density of states, adsorption energy, charge transfer, recovery time and work function of the systems showed that the pristine NbS2monolayer have poor sensor performance for sulfur-containing hazardous gases due to weak adsorption capacity, insignificant charge transfer and insignificant changes in electronic properties after gas adsorption on the surface. After doping with Cr atoms, the adsorption performance of Cr-NbS2was significantly improved, and it can be used as a sensor for SO2and H2S gases and as an adsorbent for SO3gas. The adsorption performance of Mo-NbS2is also significantly improved by doping with Mo atoms, and it can be used as a sensor for H2S gas and as an adsorbent for SO2and SO3gas. Therefore, Cr-NbS2and Mo-NbS2are revealed to be sensing or elimination materials for the harmful gases containing sulfur (SO2, H2S and SO3) in the atmosphere.

BeO nanotube as a promising material for anticancer drugs delivery system

In this research, the application of BeO nanotube (BeONT) as a nanocarrier for Fluorouracil (5-FU) anticancer drug has been studied by density functional theory (DFT) approach. The method ωB97XD with 6-31 G** basis set were employed. A precise surface study, shows that there are two directions for 5-FU adsorption that did not deliver any of the imaginary frequency vibrational spectra, identifying that all relaxation structures are at the lowest energy level. Based on our calculations, the energy of adsorption for 5FU@BeONT structures are range -120 to -168 kJ/mol, in the gas phase and -395 to 4-00 kJ/mol in the aqueous phase. The highest and the lowest values of adsorption energy are both in strong physical adsorption. Due to receiving an electronic charge from 5-FU, BeONT exhibited a p-type semiconducting feature for all positions. In addition, based on natural bond orbital (NBO) analysis, the direction of charge transfer was from fluorine's σ orbitals of the drug to n* orbitals (O and Be atoms) of BeONT with a considerable amount of transferred energy. BeONT can be employed as a potential strong carrier for 5-FU drugs for practical purposes based on our findings.

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.

Adsorption and Sensing Performances of Pristine and Au-Decorated Gallium Nitride Monolayer to Noxious Gas Molecules: A DFT Investigation

In this study, the adsorption of noxious gas molecules (NO, Cl₂, and O₃) on GaN and Au-decorated GaN was systematically scrutinized, and the adsorption energy, bond length, charge, density of state (DOS), partial density of state (PDOS), electron deformation density (EDD), and orbitals were analyzed by the density functional theory (DFT) method. It is found that the interaction between NO and pristine GaN is physical adsorption, while GaN chemically reacts with Cl₂ and O₃. These observations suggest that pristine GaN may be a candidate for the detection of Cl₂ and O₃. The highly activated Au-decorated GaN can enhance the adsorption performance toward NO and convert the physical adsorption for NO into chemical adsorption, explaining the fact that precious metal doping is essential for regulating the electronic properties of the substrate material. This further confirms the well-established role of Au-decorated GaN in NO gas-sensing applications. In addition, the adsorption performance of Au-decorated GaN for Cl₂ and O₃ molecules is highly improved, which provides guidance to scavenge toxic gases such as Cl₂ and O₃ by the Au-decorated GaN material.

DFT exploration of adsorptive performances of borophene to small sulfur-containing gases

Density functional theory (DFT) calculations were applied to study the ability of B₃₆ to adsorb H₂S, SO₂, SO₃, CH₃SH, (CH₃)₂S, and C₄H₄S gases. Several exchange-correlation including B97D, PBE, B3LYP, M062X, and WB97XD were utilized to evaluate adsorption energies. The initial results showed that boundary boron atoms are the most appropriate interaction sites. The adsorption energies, electron density, electron localized function, and differential charge density plots confirmed the formation of chemical covalent bonds only between SO_x and B₃₆. The results of thermochemistry analysis revealed the exothermic nature of the adsorption of sulfur-containing gases on B₃₆; the highest values of ∆H₂₉₈ were found for SO₃/B₃₆ and SO₂/B₃₆ systems. The electronic absorption spectra and DOS of B₃₆ did not exhibit significant variations after gases adsorption, while the modeled CD spectra showed a remarkable change in the case of the SO_x/B₃₆ system. Accordingly, B₃₆ is not suggested for detecting the studied gases. The effect of imposing mono vacancy defect and external electric field to the adsorption of titled gases on the sorbent showed, while the former did not affect the adsorption energies significantly the later improved the adsorption of gas molecules on the B₃₆ system. The results of the current study could provide deeper molecular insight on the removal of SO_x gases by B₃₆ system.

Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy for Probing Riboflavin on Graphene

Graphene research and technology development requires to reveal adsorption processes and understand how the defects change the physicochemical properties of the graphene-based systems. In this study, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and graphene-enhanced Raman spectroscopy (GERS) coupled with density functional theory (DFT) modeling were applied for probing the structure of riboflavin adsorbed on single-layer graphene substrate grown on copper. Intense and detailed vibrational signatures of the adsorbed riboflavin were revealed by SHINERS method. Based on DFT modeling and detected downshift of prominent riboflavin band at 1349 cm⁻¹ comparing with the solution Raman spectrum, π-stacking interaction between the adsorbate and graphene was confirmed. Different spectral patterns from graphene-riboflavin surface were revealed by SHINERS and GERS techniques. Contrary to GERS method, SHINERS spectra revealed not only ring stretching bands but also vibrational features associated with ribityl group of riboflavin and D-band of graphene. Based on DFT modeling it was suggested that activation of D-band took place due to riboflavin induced tilt and distortion of graphene plane. The ability to explore local perturbations by the SHINERS method was highlighted. We demonstrated that SHINERS spectroscopy has a great potential to probe adsorbed molecules at graphene.

A novel Fe-Co double-atom catalyst with high low-temperature activity and strong water-resistant for O3 decomposition: A theoretical exploration

Developing catalysts with high activity, durability, and water resistance for ozone decomposition is crucial to regulate the pollution of ozone in the troposphere, especially in indoor air. To overcome the shortcomings of metal oxide catalysts with respect to their durability and water resistance, Fe-Co double-atom catalyst (DAC) is proposed as a novel catalyst for ozone decomposition. Here, through a systematic study using density functional theory (DFT) calculations and microkinetic modeling, the adsorption and catalytic decomposition of O₃ on Fe-Co DAC have been examined based on adsorption configuration, orbital hybridization, and electron transfer. Based on Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms, the mechanisms of ozone decomposition on Fe-Co DAC were explored by analyzing reaction paths and energy variations. To confirm the water-resistant of Fe-Co DAC, competitive adsorption behavior between O₃ and dominant environmental gases was discussed through ab initio molecular dynamic (AIMD) simulation. The dominant reaction mechanism of ozone decomposition is L-H and the rate-determining step is the desorption of the first oxygen molecule from the surface of Fe-Co DAC which has an energy barrier of 0.78 eV. Due to this relatively low energy barrier and high turnover frequency (TOF), the optimal operation window of catalytic O₃ decomposition on Fe-Co DAC is <500 K suggesting that catalytic decomposition of O₃ on Fe-Co DAC can occur at room temperature. This theoretical study provides new insights for designing novel catalysts for ozone decomposition and fundamental guidance for subsequent experimental research.

Computational investigation of a covalent triazine framework (CTF-0) as an efficient electrochemical sensor

In the current study, a covalent triazine framework (CTF-0) was evaluated as an electrochemical sensor against industrial pollutants i.e., O₃, NO, SO₂, SO₃, and CO₂. The deep understanding of analytes@CTF-0 complexation was acquired by interaction energy, NCI, QTAIM, SAPT0, EDD, NBO and FMO analyses. The outcome of interaction energy analyses clearly indicates that all the analytes are physiosorbed onto the CTF-0 surface. NCI and QTAIM analysis were employed to understand the nature of the non-covalent interactions. Furthermore, SAPT0 analysis revealed that dispersion has the highest contribution towards total SAPT0 energy. In NBO analysis, the highest charge transfer is obtained in the case of SO₃@CTF-0 (−0.167 e⁻) whereas the lowest charge transfer is observed in CO₂@CTF-0. The results of NBO charge transfer are also verified through EDD analysis. FMO analysis revealed that the highest reduction in the HOMO–LUMO energy gap is observed in the case of O₃ (5.03 eV) adsorption onto the CTF-0 surface, which indicates the sensitivity of CTF-0 for O₃ analytes. We strongly believe that these results might be productive for experimentalists to tailor a highly sensitive electrochemical sensor using covalent triazine-based frameworks (CTFs).

In the current study, a covalent triazine framework (CTF-0) was evaluated as an electrochemical sensor against industrial pollutants i.e., O₃, NO, SO₂, SO₃, and CO₂.

Designing and Encapsulation of Inorganic Al12N12 Nanoclusters with Be, Mg, and Ca Metals for Efficient Hydrogen Adsorption: A Step Forward Towards Hydrogen Storage Materials

Nanoclusters such as [Formula: see text][Formula: see text] have received increased attention due to their diverse applications in the fields of optoelectronics and energy storage. In this paper, we have investigated a series of alkaline earth metal (AEM)-encapsulated [Formula: see text][Formula: see text] nanoclusters for hydrogen adsorption. Thermodynamic adsorption parameters, optical and nonlinear optical properties were investigated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. Encapsulation of AEMs (Be, Mg and Ca) is an effective strategy to improve the NLO reaction and thermodynamic and adsorption properties of [Formula: see text][Formula: see text] nanoclusters. The adsorption energies ranging from [Formula: see text]26.57[Formula: see text]kJ/mol to [Formula: see text]213.33[Formula: see text]kJ/mol for the three guests (Be, Mg and Ca) capsulated [Formula: see text][Formula: see text] nanoclusters are observed. The adsorption energy is affected by the size of the nanocage. Therefore, Ca- and Mg-encapsulated cages show higher values of adsorption energy. Overall, an increase in adsorption energy ([Formula: see text][Formula: see text]kJ/mol to [Formula: see text]91.06[Formula: see text]kJ/mol) is observed for (Be, Mg and Ca) encapsulated [Formula: see text][Formula: see text] nanoclusters compared to untreated [Formula: see text][Formula: see text] and H2-[Formula: see text][Formula: see text] cages. Moreover, adsorption of hydrogen on AEMs encapsulated in [Formula: see text][Formula: see text] leads to a decrease in the HOMO-LUMO energy gap with an enhancement of linear and nonlinear hyperpolarizability. All hydrogen-adsorbed AEMs [Formula: see text][Formula: see text] nanocages exhibit large [Formula: see text] and [Formula: see text] values, suggesting that these systems are potential candidates for optical materials. Various geometrical parameters such as frontier molecular orbitals (FMOs), partial density of states, global quantum descriptor of reactivity, natural bond orbital testing and molecular electrostatic strength analyses were performed to investigate the thermodynamic stability of all the studied systems. The results obtained confirmed that the designed systems are suitable for hydrogen storage. Therefore, we recommend that these systems be investigated for their hydrogen storage and optical properties.

Adsorption of dissolved gas molecules in the transformer oil on silver-modified (002) planes of molybdenum diselenide monolayer: a DFT study

High-sensitivity gas sensor is a crucial online monitoring device to ensure the safe operation of the transformer. In this paper, based on density functional theory, an Ag-MoSe₂monolayer system was established by investigating four different positions of Ag doping to adsorb the dissolved gas (H₂, C₂H₂, CH₄, CO and CO₂) in transformer oil. The sensing properties of adsorption system for different dissolved gas were studied via the analysis of adsorption energy (E_ad), charge transfer, density of state, energy band, lowest unoccupied molecular orbit, highest occupied molecular orbit, and desorption time. Finally, Ag-MoSe₂had good adsorption and desorption properties for CO and CH₄at room temperature, and could be used as a sensor material for the two gases detection. It had strong adsorption and poor desorption performances for C₂H₂at room temperature, which could serve as C₂H₂scavenger, and simultaneously had good adsorption and desorption performance at a temperature of 358 K, therefore it could be used as a candidate material to detect C₂H₂at high temperatures. Ag-MoSe₂had a weak interaction with H₂and CO₂, thus was not suitable for detecting the two gases. The results indicated that Ag-MoSe₂had excellent potential in detecting dissolved gases in transformer oil.

Defective GaAs nanoribbon-based biosensor for lung cancer biomarkers: a DFT study

Density functional theory-based first-principles investigation is performed on pristine and mono vacancy induced GaAs nanoribbons to detect the presence of three volatile organic compounds (VOCs), aniline, isoprene and o-toluidine, which will aid in sensing lung cancer. The study has shown that pristine nanoribbon senses all three analytes. For the pristine structure, we observe decent adsorbing parameters and the bandgap widens after the adsorption of analytes. However, the introduction of the carrier traps induced by defect causes deep energy wells that vary the electrical properties as indicated in the bandgap analysis of GaAs, wherein adsorption of aniline and o-toluidine reduces the bandgap to 0 eV, making the structure highly conductive in nature. The adsorption energies of defect-induced nanoribbon are more as compared with the pristine counterpart. Nonetheless, the introduction of defects has improved the sensitivity further.

Density functional theory-based analyses on selective gas separation by β-PVDF-supported ionic liquid membranes

Finding proper candidates for polymer-supported ionic liquid (IL)-based gas separating membranes is a challenge. The current article elucidates the quantum chemical perspective of the selective gas adsorption efficiency, from a mixture of CO₂, CO, CH₄, and H₂, of α- and β-polyvinylidene fluoride (PVDF)-supported imidazolium- and pyridinium-based six ionic liquid membranes. Although IL-based membrane efficiency mainly depends on the gas solubility of ILs, IL/support binding and gas adsorption on the support material are also studied to describe the overall gas adsorption properties of the PVDF/IL complexes. β-PVDF exhibits better binding with the ILs, and better gas affinity, thus, qualified as a more suitable membrane component as compared to α-PVDF. Dispersion-corrected density functional calculations are performed to provide a detailed insight into the energetic interactions, nonbonding intermolecular interactions based on symmetry adapted perturbation theory (SAPT), natural bond orbitals (NBO), Bader's quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), frontier orbital interactions, density of states (DOS), and thermochemical analyses of the gas-adsorbed systems. Gas molecules interact with the membrane components through weak hydrogen bonds and exhibit low interaction energies, indicating physisorption of the gases. Gas adsorption energies are more negative than the mutual interaction energies of the gas molecules, ensuring effective gas adsorption by the membrane components. All the β-PVDF/IL systems have shown the highest and lowest affinity for CO2 and H2, respectively, leading to effective separation of CO₂ and H₂ from the other gases.

SF6 decomposed gas sensing performance of van der Waals layered cobalt oxyhydroxide: insights from a computational study

The detection of SF₆ decomposition products plays a significant part in identifying and assessing the electric discharge faults in SF₆ insulation equipment. We performed dispersion corrected density functional theory calculations to study the adsorption performance of CoOOH upon SO₂, SF₄, SOF₂, CF₄, and SO₂F₂ toxic gases, to investigate their potential application as a gas sensor. The results clearly show a weak force between the CoOOH sheet, and the molecular gas with moderate adsorption strength enhances the desorption processes. According to Löwdin charge population analysis, electrons transfer from the molecular gas to the CoOOH surface, where the molecular gas behaves like an electron donor. The lower bandgap energy of the adsorption systems compared with pristine CoOOH significantly increases its electrical conductivity and gas sensing performance. The higher charge transfer and adsorption energy of the SOF₂ adsorption system compared with the other four molecular gas is due to orbital hybridization around the Fermi energy. The theoretical computed adsorption energy with ultrahigh sensitivity and fast recovery time suggests that SF₆ decomposed gases reusability is achieved with CoOOH as a resistance-type gas sensor.

Recent Developments in Graphene-Based Toxic Gas Sensors: A Theoretical Overview

Detecting and monitoring air-polluting gases such as carbon monoxide (CO), nitrogen oxides (NOx), and sulfur oxides (SOx) are critical, as these gases are toxic and harm the ecosystem and the human health. Therefore, it is necessary to design high-performance gas sensors for toxic gas detection. In this sense, graphene-based materials are promising for use as toxic gas sensors. In addition to experimental investigations, first-principle methods have enabled graphene-based sensor design to progress by leaps and bounds. This review presents a detailed analysis of graphene-based toxic gas sensors by using first-principle methods. The modifications made to graphene, such as decorated, defective, and doped to improve the detection of NOx, SOx, and CO toxic gases are revised and analyzed. In general, graphene decorated with transition metals, defective graphene, and doped graphene have a higher sensibility toward the toxic gases than pristine graphene. This review shows the relevance of using first-principle studies for the design of novel and efficient toxic gas sensors. The theoretical results obtained to date can greatly help experimental groups to design novel and efficient graphene-based toxic gas sensors.

Role of oxygen functional groups in Pb2+ adsorption from aqueous solution on carbonaceous surface: A density functional theory study

The adsorption mechanism of Pb²⁺ from aqueous solution on carbonaceous surface modified with oxygen functional groups was investigated by using density functional theory method. The zigzag model with seven benzene rings and armchair model with four benzene rings were used to simulate the different structures of carbonaceous surfaces. It was found that the adsorption of Pb²⁺ on the pure zigzag surface was chemisorption with the adsorption energy of - 306.26 to - 322.36 kJ/mol, while that on the armchair surface was physisorption with the adsorption energy of - 32.39 kJ/mol. The introduction of oxygen functional groups significantly enhanced the Pb²⁺ adsorption on the armchair surface. The physisorption changed to chemisorption after adding carboxyl, phenolic hydroxyl, or carbonyl functional group, indicating the stronger adsorption ability of the carbonaceous surfaces after modification. On the zigzag surface, however, the studied functional groups cannot benefit the Pb²⁺ adsorption. The results showed that the Pb²⁺ tended to adsorb on the carbon atoms instead of moving to the oxygen atoms from the introduced functional groups for adsorption, which suggests that the oxygen functional groups promoted the Pb²⁺ adsorption by increasing the activity of their neighboring carbon atoms.

Atomic simulation of adsorption of SO2 pollutant by metal (Zn, Be)-oxide and Ni-decorated graphene: a first-principles study

Due to the impact of toxic gases on human health, considerable interest has been shown in detecting noxious air pollutants, particularly sulfur dioxide (SO₂), both experimentally and theoretically. This work provides new insights into the adsorbing (SO₂) molecules on the surface of metal-oxide graphitic structures, i.e., Beryllium-Oxide (BeO), Zinc-Oxide (ZnO), and Ni-decorated graphene applying a first-principles study. Computational analyses suggest that the type of binding of SO₂ molecule on BeO and ZnO sheets is physisorption so that binding energies of -0.405 and -0.154 eV were assigned to ZnO and BeO nanosheets in that order. The adsorption energy of SO₂ on metal oxide sheets was much higher than the pristine graphene. Taking pristine graphene as an adsorbent for SO₂ molecule, it was found that such nanomaterial is not an efficient adsorbent due to the weak interactions (-0.157 eV) and low electron charge transfer (0.042 e) present in SO₂/graphene complex. To overcome this issue, graphene nanosheets decorated with nickel atoms were studied for interaction with SO2 molecules; the results indicate that the SO₂ molecules were chemisorbed on Ni-decorated graphene sheets with an adsorption energy of -2.297 eV. Chemisorption of SO₂ molecules on Ni-decorated graphene sheets was proven by the strong orbital hybridization between Ni 3d and sulfur 3p orbitals in the Projected Density of States (PDOS) plot. This work provides useful information about SO₂ adsorption on Ni-decorated graphene sheets in order to develop a new class of gas sensing devices. Superior chemisorption of SO₂ on Ni-decorated graphene sheets compared to the physical adsorption on BeO and ZnO sheets makes Ni-decorated graphene a potential candidate for detecting SO₂ molecules.

Theoretical Insight on the Biosensing Applications of 2D Materials

The research on the design of efficient, reliable, and cost-effective biosensors is expanding given its high demand in various fields such as health care, environmental surveillance, agriculture, diagnostics, industries, and so forth. In the last decade, various fascinating and interesting 2D materials with extraordinary properties have been experimentally synthesized and theoretically predicted. 2D materials have been explored for the sensing of different biomolecules because of their large surface area and strong interaction with different biomolecules. Theoretical simulations can bring important insight on the interaction of biomolecules on 2D materials, charge transfer, orbital interactions, and so forth and may play an important role in the development of efficient biosensors. Quantum simulation techniques, such as density functional theory (DFT), are very powerful and are gaining popularity especially with the advent of high-speed computing facilities. This review article provides theoretical insight regarding the interaction of various biomolecules on different 2D materials and the charge transfer between the biomolecules and 2D materials leading to electrochemical signals, which can then provide experimentalists the useful design parameters for fabrication of biosensors. It also includes an overview of quantum simulations, use of the DFT method for simulating biomolecules on 2D materials, parameters obtained from theoretical simulations and sensitivity, and limitations of computational techniques for sensing biomolecules on 2D materials. Furthermore, this review summarizes the recent work in first-principles investigation of 2D materials for the purpose of biomolecule sensing. Beyond the traditional graphene or 2D transition-metal dichalcogenides, some novel and recently proposed 2D materials such as pentagraphene, haeckelite, MXenes, and so forth which have exhibited good sensing applications have also been highlighted.

Computational Study on Metal-Ion-Decorated Prismane Molecules for Selective Adsorption of CO2 from Flue Gas Mixtures

Selective adsorption of CO₂ from flue gas is extremely significant because of its increasing concentration in air and its deleterious effect on the environment. In this work, we have explored metal-ion-bound prismane molecules for selective CO₂ adsorption from the flue gas mixture. The Ca²⁺-bound prismane complex exhibits superior CO₂ selectivity and adsorption capacity. The calculated binding energy and molecular electrostatic potential (MESP) analysis showed that the rectangular face of prismane binds strongly with metal ions as compared to its triangular face. The CBS-QB3 and density functional theory-based functional M06-2X/6-311+G(d) calculations show that the prismane molecule can bind to one Li⁺, K⁺, Mg²⁺, and Ca²⁺ ion with favorable binding energy. The metal-ion-bound prismane complexes have been examined for their CO₂, N₂, and CH₄ adsorption capacity. Prismane-Ca²⁺ can bind with six CO₂ molecules strongly with an average binding energy of -18.1 kcal/mole as compared to six N₂ (-12.6) and five CH₄ (-13.4) gas molecules. The gravimetric density calculated for the CO₂-adsorbed prismane-Ca²⁺ complex has been found to be 69.1 wt %. The discrete hydrocarbon structure for selective separation of CO₂ is rare in the literature and can have potential applications for cost-effective CO₂ capture from the flue gas mixture.

Efficient Cu Decorated Inorganic B12P12 Nanoclusters for Sensing Toxic COCl2 Gas: A Detailed DFT Study

Gas sensing materials have been widely explored recently owing to their versatile environmental and agriculture monitoring applications. Phosgene (COCl2) is a toxic and harmful gas, therefore, a reliable and sensitive technique is required for monitoring its quantity in the atmosphere. In this study, pure as well as copper decorated B[Formula: see text]P[Formula: see text](Cu-BP) nanoclusters were analyzed using DFT method to investigate their specific potential for phosgene gas adsorption. Cu interaction resulted in three optimized geometries S1, S2 and S3 with interaction energies of [Formula: see text]234.52[Formula: see text]kJ/mol, [Formula: see text]214.59[Formula: see text]kJ/mol and [Formula: see text]266.45[Formula: see text]kJ/mol, respectively. In all these three cases, the COCl2 prefers to interact at the top of the cage. The phosgene molecule (COCl2) interacts with bare nanocage at a distance of 3.22[Formula: see text]Å with interaction energy of [Formula: see text]6.22[Formula: see text]kJ/mol, while the observed interaction energies of phosgene at Cu decorated B[Formula: see text]P[Formula: see text] are [Formula: see text]76.90[Formula: see text]kJ/mol, [Formula: see text]119.03[Formula: see text]kJ/mol and [Formula: see text]29.60[Formula: see text]kJ/mol, respectively. To observe the variations in electronic structure, fermi level, molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs), natural bonding orbital ([Formula: see text]), softness, hardness, chemical potential and electrophilicity are calculated before and after phosgene adsorption. Energy gap reduce significantly after phosgene adsorption from 2.31[Formula: see text]eV, 2.05[Formula: see text]eV and 2.46[Formula: see text]eV to 1.54[Formula: see text]eV, 1.57[Formula: see text]eV and 2.45[Formula: see text]eV, respectively. Results of all analysis suggested that decoration of Cu significantly enhanced the adsorption power of B[Formula: see text]P[Formula: see text] nan-cluster for COCl2 molecule. Therefore, the Cu-decorated B[Formula: see text]P[Formula: see text] nanocages are considered as potential candidates for application in COCl2 sensors.

Adsorption and sensing of CO and NH3 on chemically modified graphene surfaces

We have studied the electronic structure and adsorption characteristics of environmentally potent gaseous molecules like carbon monoxide (CO) and ammonia (NH₃) on chemically modified surfaces of graphene, employing ab initio density functional methods. An insight into the changes made in the electronic band structure due to intrinsic and extrinsic doping and through a combined effect of both is discussed. With this regard, the adsorption of these gaseous moieties is investigated on substitutionally p- and n- doped graphene surfaces, doped with various mole fractions and having different configurational patterns on the surface. Even though the electronic properties are modified with various mole fractions of doping they do not show a methodical increase with the increase in the dopant concentration. This is attributed to the sub-lattice induced symmetry breaking for the dopant configurations where equivalent lattice sites are occupied on the surface. An appreciable band gap opening of around 0.63 eV is observed on doping, due to sub-lattice symmetry breaking. This is further improved on molecular doping, with CO and NH₃, where an increase up to 0.83 eV is noted with adsorption of ammonia. While both the molecules are physisorbed on nitrogen doped surfaces, carbon monoxide is strongly physisorbed and ammonia molecules are chemisorbed on a few boron doped surfaces resulting in notable changes in the adsorption energy. Therefore, it is clear that changes in the transport properties can be brought about by adsorption of these molecules on such surfaces and this study clearly indicates the invaluable prospects of such doped surfaces as potential sensors for these molecules.

We have studied the electronic structure and adsorption characteristics of environmentally potent gaseous molecules like carbon monoxide (CO) and ammonia (NH₃) on chemically modified surfaces of graphene, employing ab initio density functional methods.

Exploration of adsorption behavior, electronic nature and NLO response of hydrogen adsorbed Alkali metals (Li, Na and K) encapsulated Al12N12 nanocages

Due to the increasing demand of Al[Formula: see text]N[Formula: see text] in optoelectronics and sensing materials, we intended to investigate the adsorption behavior, electronic nature and NLO response of hydrogen and different metals decorated Al[Formula: see text]N[Formula: see text] nanocages. Different systems are designed by hydrogen adsorption and encapsulation of metals (Li, Na and K) in Al[Formula: see text]N[Formula: see text]. Density functional theory at B3LYP functional with conjunction of 6-31G([Formula: see text], [Formula: see text] basis set is utilized in order to gain optimized geometries. Different calculations including linear and first-order hyperpolarizability are conducted at same level of theory. Instead of chemiosorption, a phyisosorption phenomenon is seen in all hydrogen adsorbed metal encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters. The [Formula: see text] analysis confirmed the charge separation in hydrogen adsorbed metal encapsulated nanocages. Molecular electrostatic potential (MEP) analysis cleared the different charge sites in all the systems. Similarly, frontier molecular orbitals analysis corroborated the charge densities shifting upon hydrogen adsorption on metal encapsulated AlN nanocages. HOMO–LUMO band gaps suggest effective use of H2-M-AlN in sensing materials. Global indices of reactivity also endorsed that all hydrogen adsorbed metal encapsulated systems are better materials than pure Al[Formula: see text]N[Formula: see text] nanocage for sensing applications. Lastly, linear and first hyperpolarizability of H2-M-AlN nanocages are found to be greater than M-AlN and pure AlN nanocages. Results of these parameters recommend metal encapsulated nanocages as efficient contributors for the applications in hydrogen sensing and optoelectronic devices.

Permeation of second row neutral elements through Al12P12 and B12P12 nanocages; a first-principles study

Both exohedral and endohedral complexes of second row elements doped X₁₂Y₁₂ (X = B, Al and Y = P) nano-cages are evaluated for thermodynamic stabilities, electronic properties and kinetic barriers. Interaction energies are calculated to deeply perceive the stability of these complexes. Further, interconversion of exohedral and endohedral complexes is explored through an unprecedented approach, where 2nd row elements translate into nano-cages through boundary crossing. Subsequently, the kinetic barriers for encapsulation and decapsulation are also investigated through PES scanning of all elements by passing through hexagon of nano-cages. Systematic investigations revealed that due to larger diameter, AlP nanocage exhibits low encapsulation barriers in comparison to BP nano-cage. Such as; the encapsulation barrier of F@AlP (7.57 kcal mol^-1) is lower than that of F@BP (129.78 kcal mol^-1). Moreover, distortion of nano-cages due to translation of elements is also estimated by distortion energies. Large distortion energies of 113.81/118.39 kcal mol^-1 are noticed for exo-B@AlP/exo-C@BP complexes. In addition, the electronic properties for all the complexes are probed and depicted that the endohedral doping have remarkable influence on the electronic properties of the nanocage in comparison to exohedral doping. NBO charge analysis shows that Be metal delivers charges of 0.08 |e|/0.03 |e| to the AlP/BP nanocage, causing the later more electron rich. Contrary to Be, all other doped atoms show negative charges.

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.

Catalytic function of ferric oxide and effect of water on the formation of sulfur trioxide

Sulfur trioxide (SO₃) is not only environmentally harmful but also highly corrosive, taking a great threat to the safe operation of coal-fired power plants. A dominant pathway of SO₃ formation in coal-fired power plant is through the catalytic oxidation of SO₂ (SO₂+1/2O₂→SO₃) on the surfaces of ash particles containing Fe₂O_3. The catalytic formation of SO₃ could be affected by complex atmosphere, where the effect from H₂O is still debatable. In this paper, density functional theory (DFT) is employed to explore the reaction pathway of SO₃ formation catalyzed by α-Fe₂O₃ in complex atmosphere containing O, O₂, SO₂ and H₂O. In order to get the stable adsorption sites of these species, the adsorption energy of potential adsorption configurations on the α-Fe₂O₃ (001) surface is calculated. The dissociations of O₂ molecule on complete and defect α-Fe₂O₃ (001) surfaces with O vacancy are calculated, and the Langmuir-Hinshelwood and Eley-Rideal mechanisms for the O(ads) reaction with SO₂(ads) or SO₂ are compared. The effect of H₂O besides of SO₂ and O₂ on the formation of SO₃ is especially discussed. The DFT calculation results show that for the formation of SO₃ in gas phase, the energy barrier of 'SO₂+1/2O₂→SO₃' is 436.75 kJ mol^-1, in contrast, for the catalytic formation of SO₃ on α-Fe₂O₃ surfaces, this energy barrier becomes an order of magnitude smaller, 24.82 kJ mol^-1. O₂ molecules can dissociate on the defect α-Fe₂O₃ (001) surface with O vacancy spontaneously, indicating that the defect α-Fe₂O₃ is favorable for the dissociation of O₂, thereby promotes the formation of SO₃. The energy barrier of 'SO₂(ads)+O(ads)→SO₃(ads)' through Langmuir-Hinshelwood mechanism is much higher than that of 'SO₂+O(ads)→SO₃(ads)' through Eley-Rideal mechanism. The adsorption energy on the α-Fe₂O₃ (001) surface of H₂O is much smaller than that of SO₂ and O₂, indicating that H₂O has little effect on the adsorption of O, O₂, SO₂ and eventually the heterogeneous formation of SO₃. The DFT analysis results in this study provide a deep understanding on the reaction pathway of SO₃ catalytic formation by Fe₂O₃.

First-Principles Insight into a Ru-Doped SnS2 Monolayer as a Promising Biosensor for Exhale Gas Analysis

Realizing the diagnosis of lung cancer at an inchoate stage is significant to get valuable time to conduct curative surgery. In this work, we relied on a density functional theory (DFT)-proposed Ru-SnS2 monolayer as a novel, promising biosensor for lung cancer diagnosis through exhaled gas analysis. The results indicated that the Ru-SnS2 monolayer has admirable adsorption performance for three typical volatile organic compounds (VOCs) of lung cancer patients, which therefore results in a remarkable change in the electronic behavior of the Ru-doped surface. As a consequence, the conductivity of the Ru-SnS2 monolayer increases after gas adsorption based on frontier molecular orbital theory. This provides the possibility to explore the Ru-SnS2 monolayer as a biosensor for lung cancer diagnosis at an early stage. In addition, the desorption behavior of three VOCs from the Ru-SnS2 surface is studied as well. Our calculations aim at proposing novel sensing nanomaterials for experimentalists to facilitate the progress in lung cancer prognosis.

Adsorption of Phosgene Gas on Pristine and Copper-Decorated B12N12 Nanocages: A Comparative DFT Study

Nanostructured gas sensors find diverse applications in environmental and agricultural monitoring. Herein, adsorption of phosgene (COCl₂) on pure and copper-decorated B₁₂N₁₂ (Cu-BN) is analyzed through density functional theory (DFT) calculations. Adsorption of copper on B₁₂N₁₂ results in two optimized geometries, named Cu@b₆₆ and Cu@b₆₄, with adsorption energies of -193.81 and -198.45 kJ/mol, respectively. The adsorption/interaction energies of COCl₂ on pure BN nanocages are -9.30, -6.90, and -3.70 kJ/mol in G1, G2, and G3 geometries, respectively, whereas the interaction energies of COCl₂ on copper-decorated BN are -1.66 and -16.95 kJ/mol for B1 and B2, respectively. To examine the changes in the properties of pure and Cu-BN nanocages, geometric parameters, dipole moment, Q _NBO, frontier molecular orbitals, and partial density of states (PDOS) are analyzed to comprehensively illustrate the interaction mechanism. The results of these parameters reveal that COCl₂ binds more strongly onto copper-doped BN nanocages. Moreover, a higher charge separation is observed in COCl₂-Cu-BN geometries as compared to copper-decorated BN geometries. Therefore, these nanocages may be considered as potential candidates for application in phosgene sensors.

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.

Boron-, sulfur-, and phosphorus-doped graphene for environmental applications

The control of environmental pollutants is a global concern. Recently, heteroatom-doped graphene has drawn increasing attention due to their widespread applications in removing and detecting environmental pollutants. Owing to the introduction of heteroatoms into pristine graphene, the properties of heteroatom-doped graphene have been significantly enhanced in physic, chemistry, and biology. This review focuses on the approaches for synthesis and characterization of boron-, sulfur-, and phosphorus-doped graphene and their applications in the fields of adsorption, catalysis, and detection for environmental pollutants. The mechanisms of environmental applications, including π-π interactions, complexation, hydrophobic interactions, electronic conductivity, and active sites and reactive radicals, are elaborated. Furthermore, the challenges associated with the use of heteroatom-doped graphene materials and their prospective applications are also proposed.