Adsorption Of Carbon Monoxide Molecules Research Articles

Adsorption of chemical species onto nanographenes, pristine coronene and anchored systems as coronene−(TiO2)nn=1–4: Insights from ab initio molecular dynamics calculations

DFT (Density Functional Theory) calculations were carried out to evaluate the chemical interaction of CO (carbon monoxide) and NO (nitrogen monoxide) molecules onto nanographenes (NGs) n = 1–6 units; thus, for this range adsorption process is exhibited, excepting for n = 5 desorption is favored. On the other hand, dioxide titanium clusters (TiO2) n = 1–4 were proposed to adsorb CO molecule, atop and parallel adsorption sites were considered to attach CO molecule onto these clusters and four possible isolated models (C1-C4) are generated and as result of this chemical interaction, physisorption was obtained. In order to improve the adsorption of CO molecule, (TiO2)n−CO clusters are deposited onto (NG)2 to play the role as substrate, namely coronene (C) and then a set of nanocomposites are generated to analyze changes on adsorption tendency, for the above systems just CO molecule is considered. Some chemical and structural transition are obtained for largest sizes as well as adsorption energy values are more favored for C−(TiO2)3−CO system due to the close proximity between titanium atom of C-(TiO2)3 clusters and this chemical specie. Therefore, there are substantial chemisorption values in this instance due to the active sites. The values of the electronic gap do not exhibit significant variations, among these nanocomposites, however, the HOMO isosurfaces are shown in distinct ways, and for n ≤ 2 systems examined in this paper, LUMO isosurfaces are displayed at the center of the cluster. In all systems analyzed, the electronic transference goes from chemical species toward atoms at the adsorption site. These results suggest that these C−(TiO2)n nanocomposites are ideal candidates to storing or sense different sort of gases; thereby, these findings can be employed to design a kind of gases storage device for environmentally friendly energy applications.

Exploring the adsorption characteristics of toxic CO gas on pristine, defective, and transition metal-doped I-AsP monolayer

Utilizing first-principles calculations based on density functional theory, the adsorption characteristics of toxic carbon monoxide (CO) gas adsorbed on pristine, defective, and transition metal (TM) atoms (Sc, Mn, Fe, Ni, Cu, and Zn)-doped blue arsenic-phosphorene (I-AsP) are investigated to design potential sensing platforms. The pristine and defective monolayers exhibited weak CO gas sensing performance due to weak adsorption and unaltered electronic properties. In contrast, TM-doped monolayers exhibited strong interactions and enhanced the adsorption sensitivity due to their chemisorption behavior towards CO molecule. Furthermore, electronic properties obtained through the spin density of states analysis show significant changes in the adsorption of CO molecules on the doped I-AsP monolayer, influencing electrical conductivity. The significant change in the work function of system monolayers after CO adsorption confirmed that the TM-doped I-AsP monolayer is sensitive to CO gas. Therefore, the TM-doped I-AsP monolayer possesses strong sensitivity to CO gas, among which the Sc and Cu-doped monolayers emerge as promising candidates for toxic CO gas detection.

Aging and depth profiling of inhomogeneities and interactions of CO molecules on sputtered Pt film using ATR IR spectroscopy with lineshape analysis

Inhomogeneities in the IR site energies of carbon monoxide (CO) and its coupling to a metal continuum and subsequent interactions with metal were observed with ATR depth profiling using IR lineshape analysis with the general Fano model. After adsorption of CO molecules on a sputtered Pt film, IR center frequencies and inhomogeneities of atop and bridged molecules seem to be changed by subsequent reactions with metal and water molecules. Depth profiling indicated that the strength and inhomogeneity of coupling of bridged molecules to the metal continuum became smaller when the measurement was performed at an intermediate depth.

Transformation of the Electronic Characteristics of Ytterbium Nanofilms, Induced by Carbon-Monoxide Molecules Adsorbed on Their Surface

The adsorption of carbon monoxide (CO) molecules on ytterbium nanofilms composed of 16–200 single layers (6.1–76 nm-thick) is studied. The films are grown on grain-oriented tungsten ribbons with the preferential surface orientation (100). It is shown that, prior to the adsorption of CO molecules, ytterbium is divalent, possessing the [Xe]4f146s2 electron configuration. The adsorption of gas molecules in the surface region of the film led to the formation of a layer with trivalent ytterbium (with the [Xe]4f135d16s2 electron configuration). The minimum thickness of the ytterbium layer modified by adsorbed CO molecules is found to be composed of 16 single layers, corresponding to a thickness of 6.1 nm, which is anomalously higher than the values reported in publications.

Influence of water vapor on CO detection using a resonant microcantilever functionalized by Al-doped ZnO nanorods

A microcantilever (MC) coated by Al-doped ZnO nanorods (AZNRs) was used for carbon monoxide (CO) detection at ambient temperature. Very high sensitivity (on the order of femtograms) was obtained, which is caused by the intense adsorption of CO molecules on the AZNR surface. After the samples had been prepared and characterized, the effects of the presence of water vapor on the CO detection were investigated. Although no response was obtained for AZNRs without the presence of water vapor (i.e. under a vacuum), high sensitivity was observed in the presence of water vapor (finite humidity). Regarding the above phenomena, we propose a model that is a replacement process of the water vapor molecules by the CO molecules on the AZNR surface and discuss it in detail.

Влияние адсорбированных молекул СО на электронное состояние нанопленок иттербия, выращиваемых на кремниевых подложках

Adsorption of carbon monoxide (CO) molecules on ytterbium nanofilms with the thickness of 16 – 200 monolayers (6.1 – 76 nm) has been studied. The films are grown on single-crystal silicon substrates with the (111) surface orientation. It is shown that before the adsorption of CO molecules, ytterbium is divalent with the electronic configuration of [Xe]4f146s2. Upon the adsorption of gas molecules, a layer of trivalent ytterbium (the electronic configuration is [Xe]4f135d16s2), which is adjacent to the film surface, is formed. Evaluations of the thickness of the layer modified by adsorbed CO molecules are performed. Such evaluations have given rise to the values within 9 – 22 monolayers (3.4 – 8.4 nm).

Ab initio study of adsorption of CO on BNNTs: For gas nanosensor applications

In this study, the adsorption of carbon monoxide (CO) gas, on the surface of boron nitride nanotubes in pure form, as well as doped with Al and Ga, based on the density functional theory has been studied. The electron and structural properties of pristine and doped nanotubes have been investigated. By calculating the adsorption energy, the most stable positions and the equilibrium distance are obtained, and charge transferred and electron properties have been calculated. The most stable molecule adsorption position for pure nanotube is obtained at the center of the hexagon and for doped nanotube above the impurity. Adsorption of the molecule that is perpendicular to the nanotube axis is more stable than that with the horizontal position to the nanotube axis, and the adsorption from C atoms side is stronger than O atoms. According to the results, zigzag boron nitride nanotube is more sensitive to the adsorption of CO molecules than armchair type. The results show that gas molecule adsorption has a very slight effect on the electrical properties of pure nanotubes, which can indicate a physical adsorption. After doping, the amount of adsorption energy has changed for the most stable positions and shifted to the range of chemical adsorptions.

Performance of a novel non-platinum cathode catalyst for direct methanol fuel cells

Currently, platinum is used as the cathode catalyst in direct methanol fuel cells (DMFCs). However, platinum reduces the number of active sites for the oxygen reduction reaction (ORR) due to the reaction between platinum and methanol and the strong adsorption of carbon monoxide molecules on the platinum surface, and in addition, platinum is very expensive. Hence, this study proposes cobalt phthalocyanine/carbon-tungsten oxide nanowires (W18O49) as a non-platinum catalyst for the cathode side of a DMFC. We determined the kinetic parameters of the catalyst and investigated the factors affecting the reaction. The factors involved in the examination of the significant parameters were the synthetic method, the pyrolysis temperature, the mass ratio of CoPc to carbon, the mass ratio of CoPc/C to tungsten hexachloride and the molarity of tungsten hexachloride. The optimum parameters were determined to be a pyrolysis temperature of 600°C and a mass ratio of CoPc/C:WCl6 of 1.90. These conditions produced a peak potential at 0.63Vvs. RHE, a mass activity of 1.76Agcatalyst−1 at 0.65V, an average electron transfer number of 3.9 with water as the main product, and an electron transfer number of 3.9 at 0.65V. Finally, the results showed that the non-platinum catalyst (which is less expensive than platinum) has similar characteristics to platinum. The single cell performance test showed that the power density is 9.0mWcm−2. The catalyst has comparable performance with other macrocycle catalysts with modified structures.

Direct Visualization of Soliton CO Overlayers on Supported Pd Nanoparticles

The interaction of carbon monoxide (CO) molecules with the facets of noble metal nanoparticles forms the basis of many important catalytic reactions. Using scanning tunneling microscopy (STM), we have studied the adsorption of CO molecules on the (111) facets of Pd nanocrystals supported on a rutile TiO2(110) substrate. We observed four compact CO overlayers with coverages ranging between 0.5 and 0.6 monolayers. Examination of the positions of the CO molecules in each of the unit cells reveals that one of the overlayers has a rhombic (√7 × √7) R19.1°-4CO structure. The other three form rectangular structures, namely, (7 × √3) rect-8CO, c(5 × √3) rect-3CO, and c(9 × √3) rect-5CO. These are closely related via a soliton model previously proposed on the basis of infrared absorption spectroscopy and low-energy electron diffraction. By imaging the CO molecules, we provide direct evidence for the soliton model.

Adsorption of CO molecule on AlN nanotubes by parallel electric field

The behavior of the carbon monoxide (CO) adsorbed on the external surface of H-capped (6,0) zigzag single-walled aluminum nitride nanotube (AlNNT) was studied using parallel and transverse electric field (strengths 0-140 × 10(-4) a.u.) and density functional calculations. The calculated adsorption energies of the CO/AlNNT complex increased with increasing parallel electric field intensity, whereas the adsorption energy values at the applied transverse electric field show a significant reverse trend. The calculated adsorption energies of the complex at the applied parallel electric field strengths increased gradually from -0.42 eV at zero field strength to -0.80 eV at a field strength of 140 × 10(-4) a.u. The considerable changes in the adsorption energies and energy gap values generated by the applied parallel electric field strengths show the high sensitivity of the electronic properties of AlNNT towards the adsorption of CO on its surface. Analysis of structural parameters indicates that the nanotube is resistant to external electric field strengths. The dipole moment variations in the complex show a significant change in the presence of parallel and transverse electric fields, which results in much stronger interactions at higher electric field strengths. Additionally, the natural bond orbital charges, quantum molecular descriptors, and molecular orbital energies of the complex show that the nanotube can absorb CO molecule in its pristine form at a high applied parallel electric field, and that the nanotube can be used as a CO storage medium.

Computational study of super cell Al-substituted single-walled carbon nanotubes as CO sensor

Adsorption of carbon monoxide molecule (CO) on super cell Al-substituted (10,0) single walled carbon nanotubes (Al-substituted SWCNTs) with different concentration of aluminum is investigated by using density functional computations to find out its sensing properties for the toxic CO gas. It is found that the sensing properties substantially depends on the Al concentrations, because of band structure modifications in comparison with the pristine (10,0) SWCNT after the adsorption of CO molecule. Also, these properties are strongly dependent on the sites of the SWCNT that the CO molecule is attached. These modified nanotubes acceptable sensors for detecting the CO toxic gas.

Infrared study of effects of sulphur-poisoning on the adsorption of carbon monoxide by nickel

The effects of preadsorbed hydrogen sulphide, n-propyl mercaptan, dimethyl sulphide, thiophene and carbonyl sulphide on the adsorption of carbon monoxide by silica supported nickel have been compared by study of the infrared spectra of adsorbed carbonyl species. The formation of bridged or multicentre bonded surface carbonyl species was irreversibly poisoned by all five sulphur compounds. The strength of adsorption of carbon monoxide molecules which were linearly bonded to surface nickel atoms was weakened by sulphiding of the metal. On sulphided nickel the infrared spectra are interpreted in terms of the predominant mode of adsorption involving two and possibly three carbon monoxide molecules linearly bonded to single nickel atoms. The resulting surface species are considered to be intermediates in the formation of nickel tetracarbonyl.