Adsorption Of Nitrogen Monoxide Research Articles

Surface engineered phosphorene using boron and arsenic doping/Co-doping for Co-optimizing the adsorption stability, transduction, and recovery of CO, NO, and SO gases – A density functional theory perspective

In this work, for the first time, the effects of non-metallic Boron (B), Arsenic (As) substitutional doping as well as co-doping at different lattice positions of monolayer Phosphorene (Ph) have been extensively investigated for Carbon Monoxide (CO), Sulphur Monoxide (SO), and Nitrogen Monoxide (NO) adsorption using first principle calculation. The electronic configurations and effects of relative dopant positions (for co-doping) on atomic sub-planes of Ph significantly influence the molecular adsorptions of these monoxides, whereas the charge transfer is dominated by the molecular orientations and charge distributions of the gas molecule and host atoms near adsorption sites. The B doping notably increases the adsorption strength for each monoxide, wherein As doping increases the adsorption for CO and NO adsorption and reduces the strength for SO compared to pristine Ph. In contrast, B/As co-doping significantly and moderately increases the strength of CO/NO and SO adsorption, respectively. The co-doping exhibits a shorter recovery time while retaining adsorption stability for CO and NO. Moreover, doping/co-doping notably increases the charge transfer after NO adsorption. Finally, the NO and SO adsorptions severely alter the distribution of electronic states near the band edges, which results in significant modulations in the energy band structure of the co-doped lattice.

Experimental Investigation of the Influence of NO on a PEM Fuel Cell System and Voltage Recovery Strategies

Air contaminants can have detrimental effects on the performance and durability of proton exchange membrane (PEM) fuel cell vehicles. This research focuses on the experimental investigation of the effect of nitrogen monoxide (NO) in the cathode gas stream, which provokes a cell voltage decrease due to the partially reversible adsorption of NO on the platinum catalyst. The concentration and exposure time of NO in the cathode gas stream are varied at selected constant current densities and load ramps to assess the effects throughout the fuel cell system operating range. The results show the cell voltage loss in the presence of NO and reveal a near-catalyst saturation with increased injected NO mass. Additionally, several voltage recovery and mitigation strategies are introduced and discussed by presenting conclusions about the general effect of NO on a fuel cell system in operation. The most promising recovery strategy for fuel cell systems is identified, and the overall system degradation is discussed. All experiments are performed in a test bed environment on a 25 kW low-temperature fuel cell system via controlled injection of NO into the cathode gas stream.

Nitrogen monoxide reduction by carbon monoxide to combustion control with calcium ferrite redox in iron ore sintering

Steel industry nitrogen oxides (NOx) emission requirements are getting increasingly rigorous. Calcium ferrite around coal or coke fines controls the combustion of nitrogen monoxide (NO) reduction by carbon monoxide (CO) in an iron ore sintering bed. This control lacked mechanistic research. A hypothesis that it belongs to the redox mechanism. In an atmosphere of a combustion boundary layer with 13500 ppm CO and 450 ppm NO at 1000 °C, the transient-response method was used to investigate the effects of CO and NO on the calcium ferrite (CaFe2O4). The activity of CaFe2O4 and its reduction products in NO reduction was examined. The results show that CaFe2O4 features strong basic sites with NO storage capacity of 158.8 μmol/g⋅catalyst at high temperatures to promote the competitive adsorption of CO and NO. The CaFe2O4 reduction path by CO, which is not affected by NO, is CaFe2O4 → Fe-FeO- dicalcium ferrite(Ca2Fe2O5) → Fe-CaO. The reduced calcium ferrites have a catalytic effect of 100 % NO removal and display more pores. After CaFe2O4 reduction, the Fe-CaO oxidation path by NO is Fe-CaO → Fe3O4-Ca2Fe2O5 → CaFe2O4. Ca2Fe2O5 redox is also involved in the redox cycle that Ca2Fe2O5 → Fe-CaO by CO and then Fe-CaO → Ca2Fe2O5 by NO. A strategy of Fe-CaO around fuels is proposed to further improve the combustion control by expanding the reducing layer in the atmosphere and generating more Ca2Fe2O5.

Effects of masking titanium with a one-atom-thick carbon layer on the adsorption of nitrogen monoxide, nitrogen dioxide, ozone, and formaldehyde

We investigated the adsorption of each of four pollutant molecules, namely nitrogen monoxide, nitrogen dioxide, ozone, and formaldehyde, on the surface of a [0001] titanium slab, when it has adsorbed a one-atom-thick carbon layer. The tile is made of four titanium layers. Density functional theory and molecular dynamics were utilized. Atmospheric pressure and 300 K were considered. We found chemisorption of the four molecules on the [0001] titanium surface. Then, we optimized the interaction of the metal surface and a one-atom-thick carbon layer. The carbon atoms end up bound to titanium atoms on the surface. Carbon atoms' quasilinear chains are formed. The adsorption energy per carbon atom is − 2.054 eV. There is no migration of carbon atoms to the bulk. We found significant changes in the adsorption properties. The new system repels formaldehyde and nitrogen oxide molecules. In the ozone case, chemisorption of one oxygen atom on the surface is found, and the remaining oxygen molecule is repelled. In the nitrogen dioxide case, chemisorption of one oxygen atom on the surface is found too, and the leftover fraction is also repelled. These calculations were performed using GGA, and afterward, we utilized Vdw-DF2, which includes long-range correlation effects. The same results are obtained.

Nitrogen monoxide storage and sensing applications of transition metal–doped boron nitride nanotubes: a DFT investigation

The structural properties, electronic properties, and adsorption abilities for nitrogen monoxide (NO) molecule adsorption on pristine and transition metal (TM = V, Cr, Mn, Nb, Mo, Tc, Ta, W, and Re) doping on B or N site of armchair (5,5) single-walled boron nitride nanotube (BNNT) were investigated using the density functional theory method. The binding energies of TM-doped BNNTs reveal that the Mo atom doping exhibits the strongest binding ability with BNNT. In addition, the NO molecule weakly interacts with the pristine BNNT, whereas it has a strong adsorption ability on TM-doped BNNTs. The increase in the adsorption ability of NO molecule onto the TM-doped BNNTs is due to the geometrical deformation on TM doping site and the charge transfer between TM-doped BNNTs and NO molecule. Moreover, a significant decrease in energy gap of the BNNT after TM doping is expected to be an available strategy for improving its electrical conductivity. These observations suggest that NO adsorption and sensing ability of BNNT could be greatly improved by introducing appropriate TM dopant. Therefore, TM-doped BNNTs may be a useful guidance to be storage and sensing materials for the detection of NO molecule.

Coordinative interaction between nitrogen oxides and iron-molybdenum POM Mo72Fe30.

The process of adsorption of nitrogen monoxide and dioxide by the giant Keplerate nanocluster Mo72Fe30 was studied in detail under ambient conditions and air/argon atmosphere. The obtained Raman and IR spectra showed that the coordination of NOx to the Mo72Fe30 leads to the formation of nitrate ions by sharing the bridged or terminal oxygen in FeO6 polyhedra with the adsorbed NO2 molecules. In accordance with elemental analysis and X-ray photoelectron spectroscopy, the composition of the produced complex was found to be [POM-(NO2)x]·(NO2)y (where x = 6, y = 14 ± 3). The carried out thermal analysis revealed the significant influence of NOx coordination in the release of water molecules and decomposition of the constitutional acetate ligands for Mo72Fe30. Furthermore, the performed measurements of the temperature dependency of the electron paramagnetic resonance spectra for the pure nanocluster and that treated with NO2 allowed us to draw up a conclusion about the delocalization of weak-bonded NO2 molecules in the pores of the Mo72Fe30 crystal at 25 °C. The opposite situation was observed under cryogenic temperatures. The localization of NO2 molecules occurs resulting in the distortion of FeO6 octahedra towards tetrahedral symmetry accompanied with the appearance of the signal at g-factor 4.3. The produced complex compound [POM-(NO2)x]·(NO2)y possesses sufficient NO2 capacity, water solubility and pH-dependant decomposition; these are important properties of a potential NOx donor, which can be hypothetically applied in biomedicine.

DFT study of nitrogen monoxide adsorption and dissociation on Rh[sbnd]Cu nano clusters

Adsorption and dissociation of NO on RhxCu4-x(x = 0–4) nano clusters were investigated using density functional theory. Adsorption energy, total charge on NO, NO bond length, and NO vibrational frequency for various modes of NO adsorption were analyzed. Adsorption from the nitrogen end of NO on the Rh atom(s) of the clusters are more favored and adsorption energies are in the −1.02 eV to −2.59 eV range. NO binds stronger to Rh-Cu mixed clusters compared to pure Cu4 cluster, so NO bond is significantly weakened upon adsorption on the former. NO binding to more atoms of the clusters results in a corresponding decrease of the NO vibrational frequency. Dissociation of NO was also investigated for a proposed mechanism by calculation of dissociation Gibbs free energy. It is observed that, dissociation process on Cu4 cluster is energetically unfavorable and increasing the amount of Rh in the clusters favors the dissociation of NO.

Heterogeneous C16Zn8O8 nanocluster as a selective CO/NO nanosensor: computational investigation

Density functional theory (DFT) calculations were employed to investigate the effects of adsorption of toxic carbon monoxide (CO) and nitrogen monoxide (NO) molecules on heterogeneous C16Zn8O8 nanocage. A detailed analysis of the energetic, geometry, and electronic structure of various CO and NO adsorptions on the cluster surface was performed. It has been shown that CO molecule was adsorbed on the surface of the cluster resulting in more stable complex system, while NO molecule adsorption led to less stable system. These processes also changed the electronic properties of the cluster by reducing the HOMO/LUMO energy gap after adsorption process. Since this phenomenon led to an increment in the electrical conductivity of the cluster at a definite temperature, the C16Zn8O8 was transformed to a stronger semiconductor substance upon the CO and NO adsorption. We believe that this research may be helpful in the several fields study such as sensor and catalyst investigation.

A DFT Study of CO and NO Adsorptions on AlN-, AlP-, and ZnO-doped Graphene Nanosheets

Abstract Density functional theory calculations were performed to investigate the adsorption abilities of carbon monoxide (CO) and nitrogen monoxide (NO) gas molecules onto pristine graphene nanosheet (GNS), and AlN-, AlP-, and ZnO-doped GNSs. The co-doping of AlN, AlP, and ZnO onto GNS can improve the CO and NO adsorption abilities of GNS. The gas adsorption abilities on the pristine and co-doped GNSs were determined to be, in decreasing order: ZnO-GNS ∼ AlP-GNS > AlN-GNS > pristine GNSs and AlP-GNS > AlN-GNS > ZnO-GNS > pristine GNSs for the adsorptions of CO and NO, respectively. These newly developed co-doped GNSs could be candidates for CO and NO gas storages. The adsorption geometries, adsorption energies, density of states, and charge transfers were also reported.

Investigation of the stability of platinum clusters and the adsorption of nitrogen monoxide: First principles calculations

Density Functional Theory (DFT) calculations are performed to investigate the structural, energetic, electronic and magnetic properties of bare Ptn (n=2–6,8,10,13,30 and 39) isomers. Our calculations show that small sized Pt configurations prefer to form planar structures, while for larger size clusters, the structures tend to be compact. The most stable isomers have been selected to study the adsorption of nitrogen monoxide molecule (NO) on them. Our results show that the most stable adsorption sites of NO on Pt clusters are the top site for Pt with n=2–4, while the bridge site is favorable for the rest of the clusters (Pt with n=5,6,39). Our findings show that the bridge site of large clusters softens the NO bond more than the top site of smaller clusters.

Coordination Programming in the Design of Porous Coordination Polymers: Tuning of the Electronic Activity of Frameworks for Selective Nitrogen Monoxide Trapping

Abstract A change of building block from [Ru2II,II(p-FPhCO2)4] to [Ru2II,II(4-F-2-OMePhCO2)4] in a phenazine (phz)-bridged [Ru2II,II] chain compound led to a high selectivity toward nitrogen monoxide (NO) in the adsorption characteristics. High selectivity was observed despite the fact that electronically negative sites that enable close contact with NO molecules are not present in the pores, in contrast to [Ru2II,II(4-Cl-2-OMePhCO2)4(phz)], which also exhibited selective NO adsorption.

Influence of topological defects on the nitrogen monoxide-sensing characteristics of graphene-analogue BN

Electronic response of pristine and topologically defected boron nitride nano-sheets (h-BN) toward nitrogen monoxide (NO) molecule was investigated using density functional theory calculations. It was found that NO is weakly adsorbed on the pristine sheet, releasing an energy of 4.0kcal/mol, and the conductance and gap of the sheet are slightly changed. Although both Stone-Wales and mono-vacancy defects make the sheet more reactive toward NO, mono-vacancy defect seems to be an inappropriate strategy to manufacture NO chemical sensors due to the longer recovery time. Our calculations show that the HOMO/LUMO gap of the pristine and Stone-Wales defected h-BN sheet are significantly decreased about 42% and 35%, respectively, upon NO adsorption which may increase the electrical conductance of the sheet and it might be potentially used in NO sensors.

Nitrogen Monoxide Adsorption Property of Flocculated Fe-Included Titania Nanosheet

Nitrogen Monoxide Adsorption Property of Flocculated Fe-Included Titania Nanosheet

Decomposition of NO in automobile exhaust by plasma–photocatalysis synergy

The combination of plasma discharge and TiO2 photocatalysis exhibits high performances in the removal of nitrogen monoxide (NO). This article is aimed at elucidating the relationships between NO decomposition efficiency and various experimental parameters, including voltages, humidity and temperature. The experimental results indicate that the efficiency of NO removal by synergic plasma-catalyst coupling is significantly higher than plasma only or photocatalyst only systems. Moreover, the NO removal efficiency improves with the increase of applied voltage. Meanwhile, a higher humidity results in a reduced number of electron-hole pairs at the surface of TiO2 photocatalyst, leading to lower synergic purification efficiencies. Finally, the efficiency of NO removal is raised with the increase of temperature due to the fact that the adsorption of NO and water by nano-TiO2 is affected by environmental temperature.

Adsorption of NO on the Rh13, Pd13, Ir13, and Pt13Clusters: A Density Functional Theory Investigation

The adsorption of NO on transition-metal (TM) surfaces has been widely studied by experimental and theoretical techniques; however, our atomistic understanding of the interaction of nitrogen monoxide (NO) with small TM clusters is far from satisfactory, which compromises a deep under- standing of real catalyst devices. In this study, we report a density functional theory study of the adsorption properties of NO on the TM13 (TM = Rh, Pd, Ir, Pt) clusters employing the projected augmented wave method. We found that the interaction of NO with TM13 is much more complex than that for NO/TM(111). In particular, for low symmetry TM13 clusters, there is a strong rearrangement of the electronic charge density upon NO adsorption and, as a consequence, the adsorption energy shows a very complex dependence even for adsorption sites with the same local effective coordination. We found a strong enhancement of the binding energy of NO to the TM13 clusters compared with the TM(111) surfaces, as the antibonding NO states are not occupied for NO/TM13, and the general relationship based on the d-band model between adsorption energy and the center of gravity of the occupied d-states does not hold for the studied TM13 clusters, in particular, for clusters with low symmetry. In contrast with the adsorption energy trends, the geometric NO/TM13 parameters and the vibrational N−O frequencies for different coordination sites follow the same trend as for the respective TM(111) surfaces, while the changes in the frequencies between different surfaces and TM13 clusters reflect the strong NO−TM13 interaction.

Switching the electronic properties of Co-octaethylporphyrin molecules on oxygen-covered Ni films by NO adsorption

Using x-ray absorption spectroscopy, we demonstrate that the electronic properties of Co-octaethylporphyrin (CoOEP) molecules on oxygen-covered ultrathin Ni films can be reversibly manipulated by a chemical stimulus. This is achieved by adsorption of nitrogen monoxide (NO), leading to the formation of a NO–CoOEP nitrosyl complex, and subsequent thermal desorption of the NO from the Co ions. The integration of the absorption spectra of the Co L2,3 edges reveals a partial oxidation of the Co ions after dosing with NO compared to the pristine sample, for which a valency of 2 + and a low-spin state of the Co ions can be deduced from the Co L2,3 XAS line shape. By means of x-ray magnetic circular dichroism the magnetic moments of the Co ions were found to be coupled parallel to the magnetization of the Ni films across the intermediate layer of atomic oxygen, before and after NO uptake.

The interaction of iron pyrite with oxygen, nitrogen and nitrogen oxides: a first-principles study

Sulphide materials, in particular MoS(2), have recently received great attention from the surface science community due to their extraordinary catalytic properties. Interestingly, the chemical activity of iron pyrite (FeS(2)) (the most common sulphide mineral on Earth), and in particular its potential for catalytic applications, has not been investigated so thoroughly. In this study, we use density functional theory (DFT) to investigate the surface interactions of fundamental atmospheric components such as oxygen and nitrogen, and we have explored the adsorption and dissociation of nitrogen monoxide (NO) and nitrogen dioxide (NO(2)) on the FeS(2)(100) surface. Our results show that both those environmentally important NO(x) species chemisorb on the surface Fe sites, while the S sites are basically unreactive for all the molecular species considered in this study and even prevent NO(2) adsorption onto one of the non-equivalent Fe-Fe bridge sites of the (1 × 1)-FeS(2)(100) surface. From the calculated high barrier for NO and NO(2) direct dissociation on this surface, we can deduce that both nitrogen oxides species are adsorbed molecularly on pyrite surfaces.

Reversible Manipulation of the Magnetic Coupling of Single Molecular Spins in Fe-Porphyrins to a Ferromagnetic Substrate

We demonstrate by means of X-ray magnetic circular dichroism that the magnetization of paramagnetic Fe-octaethylporphyrin (FeOEP) molecules coupled antiferromagnetically to an oxygen-covered Co ultrathin film grown on Cu(001) can be reduced by about 50% by the adsorption of nitrogen monoxide (NO). From the similarity of Fe X-ray absorption spectra before and after NO adsorption, we conclude that this effect is the result of a reduction of the magnetic superexchange coupling between the Fe ions and the substrate caused by physisorbed NO molecules, leading to the reduced molecular magnetization. After thermal desorption of the NO from the Fe ion, the original FeOEP magnetization is restored. The reversibility of the process is proven by successfully repeating the NO dosing–desorbing procedure.

Nitrogen Monoxide Adsorption on Pt<SUB>4</SUB> Clusters Coated on γ-Al<SUB>2</SUB>O<SUB>3</SUB> (111) Surface

The nitrogen monoxide (NO) adsorption on platinum tetramer (Pt4) clusters supported on gamma alumina (gamma-Al2O3) with surface index (111) was investigated by using ab-initio calculation based on density functional theory. The Pt4 geometries used in this study are tetrahedron and planar rhombus. The adsorption of Pt4 on gamma-Al2O3 (111) surface in tetrahedron configuration is energetically more favorable as compared to that of the planar rhombus. However, it was found that NO molecule adheres strongly to Pt4 with planar configuration on gamma-Al2O3(111) surface. In addition, the NO adsorption calculation on the isolated Pt4 clusters also shows similar preference to planar configuration. The local density of states (LDOS) reveals that the difference in reactivity comes from the different hybridization strengths between the electronic states of nitrogen atom and those of platinum tetramers. The results are in good agreement with the experiments which show similar tendency for CO and N2O reactivity to gas-phase platinum clusters.

Theoretical study of nitrogen monoxide adsorption on small Si x (x = 3–5) clusters

Theoretical study of nitrogen monoxide adsorption on small Si x (x = 3−5) clusters has been carried out using the advanced hybrid meta-density functional method of Truhlar (MPW1B95). MG3 semi-diffuse basis sets were employed to improve the results. The geometry, adsorption energy, natural bond orbital charge, natural population analysis (NPA)-derived spin density and vibrational frequency of NO adsorption on all optimized nanoclusters were investigated. Also using the NPA, we have investigated the change of bond orders through adsorption. It has been found that NO is capable of making n-centre bonds (n = 1−4) from the nitrogen side but bonds to one site from the oxygen end. In the later case the N–O bond order is about 1 and a large value of spin piles up on nitrogen. Adsorption from the nitrogen side is more favoured. Reconstruction of the surface and redistribution of charges towards stable conditions caused large adsorption energies of about −180 kJ mol−1 in some structures. A number of novel structures have been proposed and optimized in this work. Also, exhaustive vibrational frequency analysis was performed to confirm the local minima energy of all optimized structures.