scholarly journals A first-principles characterization of water adsorption on forsterite grains

2013 ◽  
Vol 371 (1994) ◽  
pp. 20110582 ◽  
Author(s):  
Abu Md Asaduzzaman ◽  
Slimane Laref ◽  
P. A. Deymier ◽  
Keith Runge ◽  
H.-P. Cheng ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Water Adsorption ◽  
Gas Adsorption ◽  
Dissociative Adsorption ◽  
Single Site ◽  
Adsorption Mechanisms ◽  
Comprehensive Picture ◽  
Dual Site

Numerical simulations examining chemical interactions of water molecules with forsterite grains have demonstrated the efficacy of nebular gas adsorption as a viable mechanism for water delivery to the terrestrial planets. Nevertheless, a comprehensive picture detailing the water-adsorption mechanisms on forsterite is not yet available. Towards this end, using accurate first-principles density functional theory, we examine the adsorption mechanisms of water on the (001), (100), (010) and (110) surfaces of forsterite. While dissociative adsorption is found to be the most energetically favourable process, two stable associative adsorption configurations are also identified. In dual-site adsorption, the water molecule interacts strongly with surface magnesium and oxygen atoms, whereas single-site adsorption occurs only through the interaction with a surface Mg atom. This results in dual-site adsorption being more stable than single-site adsorption.

First-Principles Study of Interaction of Lithium Atoms with (3, 3) Carbon Nanotubes

2014 ◽  
Vol 687-691 ◽  
pp. 4311-4314 ◽  
Author(s):  
Shun Fu Xu ◽  
Ling Min Li
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Vacancy Defect ◽  
Single Wall Carbon Nanotubes ◽  
Generalized Gradient ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Adsorption Mechanisms

In this paper, we have employed first-principles calculations to investigate the adsorption mechanisms of one lithium atom on the sidewalls of 1/2/3 H-adsorbed indefective/defective (3, 3) single-wall carbon nanotubes (CNTs) which have vacancy defects. Our calculations are performed within density functional theory (DFT) under the generalized gradient approximation (GGA) of Perdew, Burke, and Ernzerhof (PBE).Our results show that the lithium atoms strongly binds to the H-adsorbed (3, 3) nanotube. Lithium atoms can chemically adsorb on (3, 3) nanotube with the vacancy defect (MVD) without any energy barrier. The lithium adsorption will enhance the electrical conductivity of the nanotube. Further more, the structure of the (3, 3) nanotube with the MVD and hydrogen atoms will become more stable after the three kinds of lithium adsorption.

scholarly journals Adsorption Characteristics of Lead-, Barium- and Hydrogen-Rich Clinoptilolite Mineral

2003 ◽  
Vol 21 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Fehime Cakicioglu-Ozkan ◽  
Semra Ulku
Keyword(s):  
Water Adsorption ◽  
Adsorption Properties ◽  
Adsorption Mechanisms ◽  
Adsorption Data ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption ◽  
Rich Material ◽  
Static Conditions ◽  
Treatment Water

The carbon dioxide and water vapour adsorption properties of local clinoptilolite-rich material, both as the original and as lead-, barium- and hydrogen-rich forms, were examined. The lead- and barium-rich forms were prepared by treatment of the original clinoptilolite with Pb(NO3)2 and BaCl2 respectively, while the hydrogen-rich form was prepared by NH4Cl and heat treatment. Water and CO2 adsorption experiments were conducted in a volumetric system under static conditions, with low-pressure adsorption data being used for the characterization of the natural, Pb-rich, Ba-rich and H-rich clinoptilolite samples. Although the existence of barium-exchange was not noted, an appreciable decrease in CO2 adsorption was observed with the Pb-rich and H-rich forms due to a decrease in the electrostatic interaction between the surface and the adsorbate. Application of the Dubinin–Astakhov equation to the water adsorption data established the existence of micropores of different sizes that exhibited different adsorption mechanisms.

Tuning the electronic and magnetic properties of Mn-doped graphene by gas adsorption and effect of external electric field: First-principles study

2019 ◽  
Vol 33 (16) ◽  
pp. 1950166
Author(s):  
Huan Ma ◽  
Ling Ma ◽  
Liang-Cai Ma
Keyword(s):  
Magnetic Properties ◽  
Electric Field ◽  
External Electric Field ◽  
Spin Polarization ◽  
First Principles ◽  
Density Functional ◽  
Gas Adsorption ◽  
Electronic And Magnetic Properties ◽  
Doped Graphene ◽  
Mn Doped

The effect of gas molecule (H2CO, NO, NO2, O2 and SO2) adsorption on the electronic and magnetic properties of Mn-doped graphene (MnG) is investigated by first-principles calculations in the framework of density functional theory (DFT). Our study reveals that after H2CO, NO, NO2 and SO2 adsorption, MnG transforms from half-metal to semiconductor, and this transformation indicates that MnG’s conductivity is changed significantly. Meanwhile, O2 adsorption has no influence on MnG’s original electronic property. Therefore, the substrate of MnG is highly sensitive to H2CO, NO, NO2 and SO2. The reconfiguration of electron distribution caused by gas adsorption dramatically alters the spin polarization distribution of the combined system, that is, NO2 and H2CO adsorption leads to local spin polarization, whereas O2, NO and SO2 adsorption result in complete spin polarization. In addition, the external electric field (E-field) is varied from −0.50 V/Å to +0.50 V/Å then applied to the adsorption system. A strong interaction is observed between gas and MnG with a positive E-field as reflected in the enhancement of adsorption energy. The interaction is obviously weakened by introducing the E-field in the negative direction. Hence, the adsorption strength and sensitivity of gas on MnG can be effectively tuned by the E-field. The results can serve as useful references for the design of graphene-based gas sensor.

First-Principles Calculation of Water Molecules with Adsorbed Ions on the Fe(001) Surface

2010 ◽  
Vol 654-656 ◽  
pp. 1662-1665
Author(s):  
Norio Nunomura ◽  
Satoshi Sunada
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
First Principles Calculation ◽  
Water Molecules ◽  
Metal Interface ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Adsorption Structure ◽  
Valence Electrons

The behavior of water molecules with sulfate on the Fe(001) surface has been investigated using a first-principles method based on density-functional theory (DFT) with numerical atomic orbitals as basis functions for the description of valence electrons and nonlocal pseudopotentials for the atomic core. We present results for the adsorption structure and the bonding nature as caused by the adsorption-induced variations in the electron density and the projected density of states. We have found that the structure of absorbed sulfate depends on the coverage of water molecule on the surface. Analysis of electrostatic potential at an aqueous metal interface provides an appropriate framework to understand complicated potential structures. The mechanism of proton transfer through dissociative adsorption and hydrogen bonding of water molecules has been obtained from calculated results.

scholarly journals First-principles theoretical investigation of graphene layers for sensor applications

2017 ◽  
Vol 7 ◽  
pp. 184798041773764 ◽  
Author(s):  
Yoshitaka Fujimoto
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Gas Adsorption ◽  
High Sensitivity ◽  
Functional Study ◽  
Graphene Layers ◽  
Sensor Applications ◽  
Adsorption Effects ◽  
Gas Molecules

Graphene is expected to be a potential device material for sensor applications due to its high charge mobility and high sensitivity to adsorbates. This article reviews the first-principles density-functional study that clarifies gas adsorption effects on graphene layers doped with boron and nitrogen atoms. We show adsorption effects of not only common gas molecules but also environmentally polluting or toxic gas molecules on stabilities and structural properties of graphene layers and carbon nanotubes. We also show physical properties induced by the adsorption of the gas molecules and discuss the possibility to detect these gas molecules.

scholarly journals Preparation of Zirconium Oxide Powder Using Zirconium Carboxylate Precursors

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Mohammed H. Al-Hazmi ◽  
YongMan Choi ◽  
Allen W. Apblett
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Experimental Findings ◽  
Periodic Dft Calculations ◽  
Good Agreement

Zirconia was prepared at low temperatures (<450°C) using single several source precursors based on zirconium carboxylates where the R groups were systematically varied. The combination of density functional theory (DFT) calculations and extensive characterization of the precursors (i.e., X-ray diffraction, thermal gravimetric analysis, infrared spectroscopy, and scanning electron microscopy) indicated that the carboxylic acid complexes may link the zirconium metal with a cis bidentate configuration. Periodic DFT calculations were performed to examine the interaction between monoclinic ZrO2 and propanoic acid. Dissociative adsorption takes place through the cis bidentate structure with an adsorption energy of −1.43 eV. Calculated vibrational frequencies using the optimized structure are in good agreement with experimental findings.

scholarly journals Effect and Characterization of Stone–Wales Defects on Graphene Quantum Dot: A First-Principles Study

2018 ◽  
Vol 3 (4) ◽  
pp. 50 ◽  
Author(s):  
Gargi Chakraborti (Banerjee) ◽  
Arka Bandyopadhyay ◽  
Debnarayan Jana
Keyword(s):  
Quantum Dot ◽  
First Principles ◽  
Density Functional ◽  
Defect Concentration ◽  
Raman Mode ◽  
Graphene Quantum Dot ◽  
Potential Applications ◽  
Distinct Existence ◽  
The Stability

A first principles based density functional theory (DFT) has been employed to identify the signature of Stone–Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21 cm − 1 in the presence of 2.08% SW defect concentration. In addition, the intensity ratio between a robust low intense contraction–elongation mode and G mode is found to be reduced for the defected structure. We have also observed a Raman mode at 1674.04 cm − 1 due to the solo contribution of the defected bond. The increase in defect concentration, however, reduces the stability of the structures. As a consequence, the systems undergo structural buckling due to the presence of SW defect generated additional stresses. We have further explored that the 1615.45 cm − 1 Raman mode and 1619.29 cm − 1 infra-red mode are due to the collective stretching of two distinct SW defects separated at a distance 7.98 Å. Therefore, this is the smallest separation between the SW defects for their distinct existence. The pristine structure possesses maximum electrical conductivity and the same reduces to 0.37 times for 2.08% SW defect. On the other hand, the work function is reduced in the presence of defects except for the structure with SW defects separated at 7.98 Å. All these results will serve as an important reference to facilitate the potential applications of GQD based nano-devices with inherent topological SW defects.

scholarly journals Understanding Cement Hydration of Cemented Paste Backfill: DFT Study of Water Adsorption on Tricalcium Silicate (111) Surface

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 202 ◽  
Author(s):  
Chongchong Qi ◽  
Lang Liu ◽  
Jianyong He ◽  
Qiusong Chen ◽  
Li-Juan Yu ◽  
...  
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Dissociative Adsorption ◽  
Molecular Adsorption ◽  
Cemented Paste Backfill ◽  
Adsorption Mechanisms ◽  
Paste Backfill ◽  
Single Water Molecule

Understanding cement hydration is of crucial importance for the application of cementitious materials, including cemented paste backfill. In this work, the adsorption of a single water molecule on an M3-C3S (111) surface is investigated using density functional theory (DFT) calculations. The adsorption energies for 14 starting geometries are calculated and the electronic properties of the reaction are analysed. Two adsorption mechanisms, molecular adsorption and dissociative adsorption, are observed and six adsorption configurations are found. The results indicate that spontaneous dissociative adsorption is energetically favored over molecular adsorption. Electrons are transferred from the surface to the water molecule during adsorption. The density of states (DOS) reveals the bonding mechanisms between water and the surface. This study provides an insight into the adsorption mechanism at an atomic level, and can significantly promote the understanding of cement hydration within such systems.

scholarly journals Role of Mg Impurity in the Water Adsorption over Low-Index Surfaces of Calcium Silicates: A DFT-D Study

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 665
Author(s):  
Chongchong Qi ◽  
Qiusong Chen ◽  
Andy Fourie
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Water Adsorption ◽  
Dissociative Adsorption ◽  
Mg Doping ◽  
Calcium Silicates ◽  
Single Water Molecule ◽  
The Impact ◽  
Mg Doped

Calcium silicates are the most predominant phases in ordinary Portland cement, inside which magnesium is one of the momentous impurities. In this work, using the first-principles density functional theory (DFT), the impurity formation energy (Efor) of Mg substituting Ca was calculated. The adsorption energy (Ead) and configuration of the single water molecule over Mg-doped β-dicalcium silicate (β-C2S) and M3-tricalcium silicate (M3-C3S) surfaces were investigated. The obtained Mg-doped results were compared with the pristine results to reveal the impact of Mg doping. The results show that the Efor was positive for all but one of the calcium silicates surfaces (ranged from −0.02 eV to 1.58 eV), indicating the Mg substituting for Ca was not energetically favorable. The Ead of a water molecule on Mg-doped β-C2S surfaces ranged from –0.598 eV to −1.249 eV with the molecular adsorption being the energetically favorable form. In contrast, the Ead on M3-C3S surfaces ranged from −0.699 eV to −4.008 eV and the more energetically favorable adsorption on M3-C3S surfaces was dissociative adsorption. The influence of Mg doping was important since it affected the reactivity of surface Ca/Mg sites, the Ead of the single water adsorption, as well as the adsorption configuration compared with the water adsorption on pristine surfaces.

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