Magnitude Of Adsorption Energy Research Articles

In silico investigation on interaction of small Ag6 nano-particle cluster with tyramine neurotransmitter

The interaction of tyramine neurotransmitter with silver nano-particle (Ag6) cluster is explored in terms of the molecular structure, electronic properties and NBO analysis of tyramine-AgNPs bio-molecular conjugate. The adsorption mechanism of tyramine onto the Ag6 cluster has been investigated through computing of the electronic and geometrical properties in addition to the adsorption energies in various possible configurations. The magnitude of adsorption energy corresponding to the most favorable tyramine-Ag6 bio-molecular conjugate has been computed to be − 14.36 kcal/mol in the gas phase, which infers a good adsorption of tyramine with AgNPs cluster suggesting the practical applications of tyramine-AgNPs bio-molecular conjugates in bio-sensing, drug delivery, bio-imaging and other applications. Different electronic properties such as the energy gap of HOMO–LUMO, Fermi level and work function have been investigated in detail. Moreover, the effect of aqueous media on adsorption energy and electronic properties of the most favorable tyramine-AgNPs bio-molecular conjugate is investigated in order to understand the impact of the real biological situation.

A DFT study on selective adsorption of NH3 from ammonia synthesis tail gas with typical aromatic boranes

Adsorption of NH3 from ammonia synthesis tail gas is a kind of dry deamination technology that can avoid the environmental problems associated with discharging ammonia-containing wastewater with traditional scrubbing technique. Here, the adsorption properties of different aromatic boranes on NH3, N2, H2 and CH4 are examined by density functional theory (DFT). It is demonstrated that the adsorbents show superior adsorption performance on NH3 among the selected gas molecules. The magnitude of adsorption energy on NH3 for aromatic boranes decreases sharply as the number of benzene ring on borane increases. Meanwhile, the position of methyl on benzene ring does not heavily affect the adsorption performance of aromatic boranes. According to the selectivity coefficient, the adsorbents have high selectivity for NH3 and NH3 can be desorbed readily at elevated temperature or reduced pressure. This study has the potential to offer valuable insights into the mechanism of NH3 adsorption and provide guidance for the design and development of aromatic borane adsorbing materials.

Histamine sensing by boron and silicon doped C60 fullerenes: A first principles investigation

The present study reports adsorption mechanism of histamine on the surfaces of pure, B- or Si-doped fullerenes. The adsorption of histamine on pure and doped fullerenes has been investigated through density functional theory calculations in the terms of stability, geometry, work function, electronic properties, and density of state spectra. The magnitude of adsorption energies has been computed to be −1.66, −35.29, and −37.43 kcal/mol for histamine corresponding to the most favorable adsorption configurations respectively. The band gap analysis revealed that the electrical conductivity of pure fullerene remains nearly constant even after histamine adsorption. However, the doping of boron and silicon leads to the decrease of the band gap after histamine adsorption resulting increment in the electrical conductivity which infers that boron and silicon doped fullerenes are more sensitive towards histamine adsorption than pure fullerene. Moreover, the NBO calculations showed charge transfer of 0.008, 0.409, and 0.272e from histamine to pure, boron and silicon doped fullerenes in the most favorable adsorption configurations, respectively.

Engineering 2D MoS2 for Enhanced Selectivity and Sensitivity of Selected Green House Gases (CO2, CH4 and N2O): An ab initio Study

2D MoS2 has been identified as a potential material for greenhouse gas (CO2, N2O, and CH4) sensing, however, the underlying principles are not well understood yet such knowledge may offer optimization opportunities for the development of superior devices. Using ab initio Density Functional Theory approach, selected dopants X (X= Cl, O, P, and Se) were judiciously introduced on 2D MoS2 and the response of the modified monolayer to the various greenhouse gases analyzed. The results showed that when the gas molecules are introduced within the periphery of the dopant site, the gases become adsorbed on the dopant with interactions that are characteristic of physisorption due to moderate adsorption energies. Based on the magnitude of adsorption energies, Cl, P, and O doped 2D MoS2 were found to be sensitive and selective to CO2, N2O and CH4 gas molecules respectively. Further, charge transfer analysis of CO2, and N2O adsorbed on Cl and P doped 2D MoS2 monolayer respectively, showed that these gas molecules gain electrons from the doped 2D MoS2 monolayer during adsorption, while CH4 molecule loses electrons to O doped 2D MoS2 surface. In addition, CO2, N2O, and CH4 gas molecules are desorbed from the surfaces of Cl, P, and O doped 2D MoS2 at 432 K, 438 K and 298 K respectively, thus rendering the modified monolayer re-usable detection of greenhouse gases. Cl doped 2D MoS2 monolayer showed superior performance in CO2 detection due to its fast recovery time and moderate thermal treatment temperature.Our results reveal that the competitive adsorption at the X doped 2D MoS2 surfaces between the analyte and the greenhouse gas present in the atmosphere induces a switching in surface conductance that can be related to the greenhouse gases concentration and can be detected electronically, thus disclosing the sensing mechanism and optimization route that can guide future experimental studies.

Investigating the structural, electronic, adsorption and optical properties of Te-doped g-ZnO monolayer before and after adsorbing Hg0 and HgCl2, using DFT + U, TDDFT and DFT-D2 approaches

The electronic and optical properties of Te doped g-ZnO monolayer before and after adsorbing Hg0 and HgCl2 have been studied by DFT approach. Given the sign and magnitude of adsorption energies, these adsorptions are possible. According to the band structure of ZnO + Te, ZnO + Te + Hg0 and ZnO + Te + HgCl2 layers, the g-ZnO gap changed into semiconductor range. By calculating the absorption spectrum, using the TDDFT, we found that all cases have the similar peaks in the ranges of FUV and EUV. These two adsorptions increase the intensity of peaks. The adsorption of Hg0 creates a peak in the MUV range. In addition, the ZnO + Te + Hg0 has a peak in the visible range. By adsorbing HgCl2, a peak appears in the IR-A range. For the resulting materials, having UV/Vis/IR peaks makes it possible to use them in photovoltaic devices. After adsorbing HgCl2 and Hg0 by ZnO + Te monolayer, the step behavior of index of refraction is enhancing.

Effects of van der Waals Interactions in the Adsorption of Isooctane and Ethanol on Fe(100) Surfaces.

van der Waals (vdW) forces play a fundamental role in the structure and behavior of diverse systems. Because of development of functionals that include nonlocal correlation, it is possible to study the effects of vdW interactions in systems of industrial and tribological interest. Here we simulated within the framework of density functional theory (DFT) the adsorption of isooctane (2,2,4-trimethylpentane) and ethanol on an Fe(100) surface, employing various exchange–correlation functionals to take vdW forces into account. In particular, this paper discusses the effect of vdW forces on the magnitude of adsorption energies, equilibrium geometries, and their role in the binding mechanism. According to our calculations, vdW interactions increase the adsorption energies and reduce the equilibrium distances. Nevertheless, they do not influence the spatial configuration of the adsorbed molecules. Their effect on the electronic density is a nonisotropic, delocalized accumulation of charge between the molecule and the slab. In conclusion, vdW forces are essential for the adsorption of isooctane and ethanol on a bcc Fe(100) surface.