Adsorption Of HCN Research Articles

First-principles study of WS2 monolayer decorated with noble metals (Pt, Rh, Ir) as the promising candidates to detect nitrogenous poisonous gases

Rapid identification of nitrogenous toxic gases (NPGs, including NO, NO2, NH3, and HCN) emitted from industrial processes is essential for environmental preservation. In this research, the first-principles calculations have been employed to systematically investigate the adsorption behavior and sensing characteristics of Pt, Rh, Ir-modified WS₂ monolayers (Pt-WS2, Rh-WS2, and Ir-WS2) towards these NPGs, with the aim of assessing the potential of WS2-based gas sensors for NPG detection. The results show that Pt, Rh, and Ir atoms can be stably anchored on the WS2 surface, enhancing its chemical stability and the quantity of active sites. Additionally, the strong orbital hybridization between these noble metal atoms and gas molecules enhances the adsorption capacity of WS₂, markedly boosting the adsorption potency of these modified substances towards NPGs (Eads≥−0.69 eV) while maintaining high selectivity toward NPGs in the presence of interfering gases (H2O, N2, CO2). Analysis of the density of states, charge density distribution, and electron localization function indicates weak chemical adsorption of HCN on Pt-WS2, Rh-WS2, and Ir-WS2, while strong chemical adsorption is observed for NO, NO2, and NH3. Furthermore, the adsorption of NO and NO₂ leads to significant band gap changes (∆Eg > 30 %) of Pt-WS2, Rh-WS2, and Ir-WS2, and the response of work function to NH₃ and HCN adsorption is similarly pronounced (∆Φ > 15 %). Finally, analysis of recovery time indicates that Pt-WS2 and Rh-WS2 can serve as work function gas sensors for HCN and as adsorbents for NO, NO2, and NH3 at room temperature, whereas Ir-WS2 can function as a reusable gas sensor for the effective detection of HCN at high temperature. This investigation establishes a robust theoretical framework for the development and manufacture of high-performance WS₂-based gas sensors.

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.

First-principles study of CH2O, CH4, Cl2, HCN, and CNCl gas adsorption behavior by h-BN boron site modification

The potential application of metallic boron bit-doped hexagonal boron nitride monolayers (h-BN@M, M = Fe, Sn, Cu, Zn) as materials for the detection of hazardous gases (CH2O, CH4, Cl2, HCN, and CNCl) has been investigated based on the first nature principle. h-BN@Fe exhibits chemisorptive properties for the adsorption of HCN and CNCl and h-BN@Sn exhibits chemisorption and appropriate humidity resistance. The recovery time of HCN on the h-BN@Fe surface and CNCl on the h-BN@Sn surface was significantly shortened under the 392 K ultraviolet light attempt frequency. In the presence of an applied electric field, HCN and CNCl on the h-BN@Fe surface and CNCl on the h-BN@Sn surface showed adjustable recovery times. This suggests that it is possible to design gas sensing devices with good adsorption characteristics on metallic boron bit-doped hexagonal boron nitride monolayers. In the future, the performance of these materials for the detection of hazardous gases will be improved by changing their structure and composition.

Adsorption of HCN, HNC and CH3CN toxic gases on the M-doped (M = Cr, Fe, Ni and Zn) GaNNS: A DFT-D study

In this work, the performance of transition metal-doped gallium nitride nanosheets (M-GaNNSs, M = Cr, Fe, Ni and Zn) for adsorption and sensing of HCN, HNC and CH3CN toxic gases were investigated at the Grimme-corrected Perdew–Burke-Ernzerhof/double numerical plus polarization (PBE/DNP) level of theory. The electronic properties, structural parameters, adsorption energies, density of states (DOS) curves, band gap energies and charge transfer values were analyzed to find the ability of eight metal-doped GaNNS in adsorbing and sensing HCN, HNC and CH3CN gases. Compared with pure GaNNS, in all eight metal-doped configurations, the adsorption energies were increased after the doping of metals, especially their value in 2-HCN-FeNGaNNS, 2-HNC-FeNGaNNS and 2-CH3CN-FeNGaNNS were greater than in others. Therefore, the FeNGaNNS may be a suitable candidate for adsorbing and removing all the three studied gases from the atmosphere. Upon adsorption of HCN, HNC and CH3CN gases on the metal-doped GaNNS, a significant change in the energy gap is found in 2-HCN-CrNGaNNS, 1-HNC-FeGaGaNNS and 2-CH3CN-CrNGaNNS complexes, and, in turn, in the conductivity of nanostructures. Therefore, it is predicted that, CrNGaNNS for sensing HCN and CH3CN gases and FeGaGaNNS for sensing HNC gas have a high potential. Although, FeGaGaNNS could be a good sensor for HCN and CH3CN gases in the second step and after CrNGaNNS.

Density functional theory analysis of the sensitivity of silicene/graphene heterostructures toward HCN

This study investigated the adsorption behavior of HCN molecules on pristine, vacancy-induced defects, and transition-metal doped silicene/graphene heterostructures based on density functional theory. The HCN molecules exhibited physical adsorption on pristine silicene/graphene substrates. Introducing Si vacancies did not enhance the activity of silicene/graphene heterostructures, and the HCN molecules continued exhibiting physical adsorption. By contrast, the presence of dopant atoms (Sc, Ti, V, Cr, Mn, Co) enhanced the adsorption stability of HCN molecules. The adsorption of HCN on Ti-doped silicene/graphene heterostructures was the highest, and the results of the partial density of states indicated obvious hybridization between d orbitals of Ti and the p orbitals of HCN molecule. Sc-doped heterostructures exhibited shortest desorption time, suggesting it was suitable as reused sensors for detecting HCN. The obtained results provide new approach for the development of highly sensitive gas sensors based on heterostructures.

Insights into different toxic molecular gases on the Fe-dimer anchored at C2N monolayer as potential sorbents and gas sensors: A theoretical approach

The fundamental aspects, including geometric structure, adsorption energy, thermodynamic properties, charge transfer, and magnetic properties of carbon nitride C2N and double-atom catalyst (Fe2@C2N) monolayers with the adsorption of CO, NO, HCN, CS2, and SO2 molecules, were investigated using DFT and DFT-D3 correction dispersion methods. Compared to pristine C2N, the Fe2@C2N monolayer is more energetically efficient with high adsorption energies and has apparent charge transfer with these toxic gases. Our results revealed that NO preferred to be adsorbed on the Fe2@C2N with a superior Eads of −7.006 eV. The electric conductivity, sensitivity, and selectivity of C2N are significantly influenced by CO, NO, HCN, CS2, and SO2 molecules. Moreover, the opening of band gaps induced by the adsorption of NO gas molecules at Fe2@C2N can be used as an electronic signal to detect NO gas. Intriguingly, the partial density of states (PDOS) indicated that the NO adsorption of pristine C2N and Fe2@C2N monolayers exhibited half-metallicity behavior and magnetic properties. Non-covalent interactions (NCI) and the quantum theory of atoms in molecules (QTAIM) descriptors were examined to analyze the interaction process. This study can provide a new avenue for synthesizing and developing highly sensitive candidates and inexpensive green double-atom catalysts to capture and detect CO, NO, HCN, CS2, and SO2 molecules from the atmosphere at ambient temperature.

Dispersion interactions with analytes at the center of graphene nanoflakes turn into electrostatic at the edge

Adsorption of small gaseous molecules on the center and edges of polycyclic aromatic hydrocarbons is studied through density functional theory calculations. The choice of selected functional for the study is based on a benchmarking, where 37 functionals are evaluated at low cost basis set against high level DFT SAPT calculations for adsorption of water molecule on coronene and hexabenzocoronene. After benchmarking, the detailed analysis is performed for the adsorption of H2S, H2O, NH3, CH3OH, HCN, H2O2 and NH2NH2 on coronene at its center and edges. The coronene is chosen to better elucidate the edge effect on the adsorption of analytes. All of the studied analytes are physiosorbed on coronene with adsorption energies ranging from 1 to 6 kcal mol−1. These complexes are stabilized by X-H---π interactions between analytes and coronene surface. The SAPT0 analysis reveals that the X-H---π interactions at the center (non-edge) position of coronene are dominated by dispersion interaction whereas the similar interactions at the edges are dominated by electrostatic interactions. The change from dispersion to electrostatic on edges is attributed to polarization of the systems by C–H polarity differences. The complexes having lone pair---π interactions have unexpectedly repulsive electrostatic interactions in H2S@GNF and NH3@GNF complexes. Electronic properties reveal that coronene surface is highly selective for hydrazine whereas adsorption of other analytes does not bring any significant changes in the electronic structure of coronene. The high selectivity of coronene for NH2NH2 is also evident from the redistribution of densities in frontier molecular orbitals. For NH2NH2@GNF complexes, the HOMOs are present on hydrazine whereas LUMOs are present in coronene. For other analytes, HOMOs and LUMOs are present merely on graphene nanoflake. This high sensitivity of coronene for hydrazine is due to better overlap of frontier molecular orbitals of analyte with coronene.

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 1.93ns, 0.45ns, and 36.31ns, 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 (3.629Å) 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.

Adsorption of HCN on WSe2 monolayer doped with transition metal (Fe, Ag, Au, As and Mo)

In this paper, the adsorption performances for HCN upon pure and metal (Fe, Ag, Au, As and Mo) doped WSe2 monolayers are analyzed on the ground of the density functional theory (DFT) and the best sites of doping are assumed. The adsorption performance of intrinsic WSe2, Fe-WSe2, Ag-WSe2, Au-WSe2 and Mo-WSe2 to HCN molecule were simulated according to the charge transfer, DOS and molecular orbital. The results manifest that all metal (Fe, Ag, Au, As and Mo) doped WSe2 monolayers have better adsorption properties for HCN. Nevertheless, occurrence of chemisorption only exists in HCN/Mo-WSe2 system, indicating this system might be candidate materials for the adsorption of HCN. Besides, after adsorption, the conductivity of all systems changes a lot, meaning that monitoring conductivity change of all systems above could be a method to sensing HCN. Thus, all metal (Fe, Ag, Au, As and Mo) doped WSe2 could be favorable materials for HCN detection.

Effect of doping and vacancy defect on the sensitivity of stanene toward HCN

The adsorption behaviour of HCN molecule on a modified stanene substrate is investigated using first-principles calculation. The large adsorption distance, small adsorption energy and low charge transfer indicated that HCN molecule exhibits a weak physical adsorption mechanism on stanene. After introducing dopant and vacancy defects in the stanene substrate, the adsorption mechanism of HCN transformed into chemisorption. The significantly increased adsorption energy suggested that the interaction between the doped substrate and HCN was enhanced. Interestingly, the Cr-doped system not only exhibited a large charge transfer but also an intense magnetic performance. Our calculation results may provide useful information for fabricating stanene-based sensors. Highlights The adsorption of HCN on intact stanene is physical adsorption. The adsorption of HCN on vacancy defect stanene is chemisorption. The Cr doped vacancy-defected stanene is suitable for the HCN gas sensor.

Effects of the HCN adsorption on the structural and electronic parameters of the Si2BN: Density functional theory studies

In this study, a simulation is run in order to investigate the ability of Si2BN to adsorb HCN based on density functional theory using generalized gradient approximation and van der Waals correction. The changes in the atomic position, electronic properties, and molecular orbitals of Si2BN are investigated due to HCN adsorption. Moreover, 48different configurations are investigated to find the most suitable gas adsorption site. Finally, the chemical adsorption of HCN along the Si-Si bond with the adsorption energy of 1.59 eV and activation energy of 1.27 eV obtained from the nudged elastic band calculations is considered a suitable option for HCN adsorption. The electron charge transfer is found to be about 0.4e and it is investigated using Voronoi charge, Mulliken charge, and natural bond orbital analysis. In addition, the change of density of states induced by the N atom of the HCN, the increase in the work function and polarization, and the decrease in conductivity indicate that Si2BN is a very suitable adsorbent for the HCN. Aamong two-dimensional materials and nanostructures, Si2BN is a potential candidate for HCN sensor application. Moreover, the comparison of the adsorption energy of different gases on Si2BN shows that the highest adsorption energy is related to HCN.

Investigation on adsorption properties of HCN and ClCN blood agents on θ–phosphorene nanosheets – A first–principles insight

We investigated the electronic features and structural firmness of θ–phosphorene nanosheet (TPNS) based on density functional theory. The formation energy endorses the structural firmness of TPNS. The semiconducting nature of TPNS with an energy band gap of 1.326 eV supports its use as a base substrate to adsorb toxic blood agents, such as HCN and ClCN. The adsorption characteristics of HCN and ClCN were established using adsorption energy, charge transfer, and deviation in band gap of TPNS. Also, the change in the electronic properties of TPNS upon adsorption of HCN and ClCN has conversed with regard to band structure, density of states spectrum, and electron density. The overall findings suggest the use of θ–phosphorene nanosheets as a sensing medium for toxic HCN and ClCN molecules.

Adsorption of NO2, HCN, HCHO and CO on pristine and amine functionalized boron nitride nanotubes by self-consistent charge density functional tight-binding method

The adsorptions of toxic gases including NO2, HCN, HCHO and CO molecules on the pristine and amine functionalized (5,0) single-wall boron nitride nanotubes (BNNTs) are investigated based on self-consistent charge density functional tight-binding (SCC-DFTB) method. The calculated results indicate that the pristine (5,0) BNNT exhibits weak adsorption for the gas molecules. Based on the calculated adsorption energy, interaction distances and charge transfer, amine functionalization at a boron atom of the pristine (5,0) BNNT enhances the sensitivity of the pristine (5,0) BNNT toward the gas molecules. The electronic densities of state results reveal that new local states in the vicinity of Fermi level for adsorption between amine functionalized BNNT and the gas molecules significantly appear. This confirms the improved sensitivity of the pristine (5,0) BNNT functionalized with amine for adsorption of the toxic gases. This study is expected to provide a useful guidance on gas sensing application of pristine and amine functionalized BNNTs for detection of the toxic gases at room temperature.

Adsorption of gas molecules on a C3N monolayer and the implications for NO2 sensors

Recent reports have raised exciting prospects for the use of C3N monolayers exhibiting excellent adsorptive properties in nanodevice applications. In this study, we carried out first-principle calculations to investigate the adsorption of NO2, NO, CO, HCN, NH3, CO2, H2, N2, CH4, H2O, O2, and N2O gas molecules on a C3N monolayer as well as its potential applications in gas sensor devices. Our results reveal that the chemisorption of NO2 can significantly influence the electronic properties of the C3N monolayer (e.g., changing semiconducting behavior to conducting behavior). In contrast, physisorption of the other gas molecules had little effect on the electronic properties of the C3N monolayer. These results suggest that the C3N monolayer is much more sensitive and selective to NO2 than to the other gases. The recovery time of NO2 at T = 300 K is only 0.62 s. Moreover, the optical properties of the C3N monolayer can be modified as a result of the adsorption of different molecules, especially the NO2 molecule. Thus, the C3N monolayer is a promising and desirable candidate for use as a suitable material in gas sensors for NO2 detection.

Adsorption behaviors of HCN, SO2, H2S and NO molecules on graphitic carbon nitride with Mo atom decoration

In this paper, we explored the adsorption structure, electronic states, and charge transfer of toxic gas molecules, including HCN, SO2, H2S and NO, on pristine and Mo atom embedded graphitic carbon nitride (g-C3N4) by first-principles calculations. Our results show that single Mo atom prefers to be embedded at the six-fold cavity with high stability. The adsorption of those gas molecules on pristine g-C3N4 monolayer exhibits weak interaction, while Mo atom doping can significantly enhance their adsorption energy. Partial density of states analysis illustrate strong hybridization among Mo-4d, gas molecule and g-C3N4. Charge transfer analysis indicates that HCN, SO2, and NO act as acceptors, while H2S acts as donor. The magnetism of g-C3N4/Mo also undergoes great change after the gas molecules adsorption. The adsorption of HCN, SO2, H2S makes the system exhibit semimetal properties, while the adsorption of NO produces much smaller magnetic moment. Therefore, the magnetism of the Mo/g-C3N4 can be modified by the gas molecule adsorption. Our calculations demonstrate that Mo decorated g-C3N4 monolayer can be a promising adsorbent for gas molecule and the variation of magnetic moment through gas adsorption can also be utilized.

Interaction of different types of nanocages (Al12N12, Al12P12, B12N12, Be12O12, Mg12O12, Si12C12 and C24) with HCN and ClCN: DFT, TD-DFT, QTAIM, and NBO calculations

In this work, the ability of different types of nanocages including Al12N12, Al12P12, Be12O12, B12N12, Si12C12, Mg12O12 and C24 for the adsorption and detection of poisonous gases HCN and ClCN has been investigated, theoretically using the D3 dispersion corrected density functional theory (DFT-D3). The absorption spectra of HCN–nanocage and ClCN–nanocage complexes were calculated by the time-dependent density functional theory (TD-DFT) and compared with the calculated absorption spectrum of isolated nanocage to investigate the ability of nanocage for sensing of HCN and ClCN gases. It was found that the strongest interaction between HCN (ClCN) molecule and nanocage takes place when the molecule is adsorbed via its N atom on the surface of nanocage except for C24. Also, it was shown that the Al12N12 is the best adsorbent for HCN and ClCN gases among the selected nanocages and Si12C12 is the best sensor for the detection of these gases using the electroconductivity and absorption spectroscopy techniques.

Reaction pathways for HCN on transition metal surfaces.

The adsorption and decomposition of HCN on the Pd(111) and Ru(001) surfaces have been studied with reflection absorption infrared spectroscopy and density functional theory calculations. The results are compared to earlier studies of HCN adsorption on the Pt(111) and Cu(100) surfaces. In all cases the initial adsorption at low temperatures gives rise to a ν(C-H) stretch peak at ∼3300 cm-1, which is very close to the gas phase value indicating that the triple CN bond is retained for the adsorbed molecule. When the Pd(111) surface is heated to room temperature, the HCN is converted to the aminocarbyne species, CNH2, which was also observed on the Pt(111) surface. DFT calculations confirm the high stability of CNH2 on Pd(111), and suggest a bi-molecular mechanism for its formation. When HCN on Cu(100) is heated, it desorbs without reaction. In contrast, no stable intermediates are detected on Ru(001) as the surface is heated, indicating that HCN decomposes completely to atomic species.

Metal-doped ethylene complexes for hazardous gas molecule sensing

Adsorption of hazardous gas molecules viz. NH3, HCN and Cl2 on C2H4M (M = Li, Ti) complex is studied using first-principle calculations and atom-centred density matrix propagation (ADMP) molecular dynamic simulations. Interaction of gas molecules with C2H4M complex is studied by analysing structural parameters, charge transfer and density of state plots. Adsorption of NH3, HCN and Cl2 molecules affects the binding energy of metal atom to the C2H4 substrate in C2H4M complex. ADMP molecular dynamic simulations confirmed that the NH3, HCN and Cl2 molecules remain adsorbed during the simulation on C2H4M complex for the entire temperature and pressure range considered. C2H4M complex can be used as a gas sensing material for NH3, HCN and Cl2 molecules.

Investigation of competitive COS and HCN hydrolysis reactions upon an industrial catalyst: Langmuir-Hinshelwood kinetics modeling

Distinct and simultaneous COS and HCN hydrolysis reactions over an industrial TiO2 based catalyst were extensively studied in this work in the scope of synthesis gas purification applications. 144 experiments were carried out, including 92 experiments that allowed to achieve partial conversion rates and showed reaction kinetics sensitivity to operating parameters. Significant crossed influences were evidenced between both COS and HCN hydrolysis reactions. The concomitant occurrence of both reactions showed to detrimentally affect each other upon COS and HCN conversion rates, and therefore upon kinetic rates. This was explained through a competitive adsorption of HCN and COS reactants upon catalyst surface active sites. Inhibition of catalytic activity by the presence of NH3 and H2O was also evidenced and explained through competitive adsorption phenomena. For the operating conditions ranges explored, H2S and CO2 had no sensitive impact on the kinetics of the COS and HCN hydrolysis reactions. However, the moderate impact of CO2 upon COS and HCN conversion rates might be explained by the large CO2 excess compared to COS and HCN levels. A reaction model has been fully developed considering hydrodynamic, external mass transfer and intra particle diffusion limitations, and Langmuir-Hinshelwood reaction mechanisms for both COS and HCN hydrolysis reactions. Langmuir-Hinshelwood kinetic rate laws were indeed considered to account for the detrimental effect of gaseous species upon COS and HCN conversion kinetic rates, through competitive adsorption upon catalyst active sites of COS, HCN, H2O, and NH3. Collected kinetic data as a function of reactor size, gas residence time, temperature and reactants partial pressures were used to validate and fit kinetic and adsorption constants. Very good agreement was achieved between experimental and calculated COS and HCN conversion rates from the model developed, that allowed complete validation of the Langmuir-Hinshelwood based modeling. The coupled hydrodynamic-reaction model also constitutes a complete industrial reactor model taking into account all the potential limitations, and can be used as a powerful predicting tool for industrial process design, i.e. fully usable for industrial process scale-up and optimization purposes.

The polythiophene molecular segment as a sensor model for H2O, HCN, NH3, SO3, and H2S: a density functional theory study

Studying the interaction of some atmospheric gases (H2O, HCN, NH3, SO3 and H2S) with 3PT oligomers is important in the development of polymeric sensors for gas detection. In the present study, we studied the relaxed geometries, interaction energies, charge analysis, HOMO-LUMO orbital analysis, and UV-vis spectra of all interacted systems using first-principles density functional theory (DFT). All these analyses indicated the potential of polythiophene as an inexpensive polymeric sensor for the analytes mentioned. Interaction energy values of -19.90, -19.66, -14.01, -8.70, and -4.76kJmol(-1) were achieved for adsorption of SO3, H2O, NH3, HCN, and H2S on 3PT, respectively. Consequently, clarification of their physical parameters became the major focus of this study.