Co-adsorption of water and oxygen on GaN: Effects of charge transfer and formation of electron depletion layer

2017 ◽  
Vol 147 (10) ◽  
pp. 104703 ◽  
Author(s):  
Qi Wang ◽  
Ajinkya Puntambekar ◽  
Vidhya Chakrapani
Keyword(s):  
Charge Transfer ◽  
Co Adsorption ◽  
Depletion Layer ◽  
Adsorption Of Water

In situ AFM and XPS Investigation of U6+ Reduction by Fe2+ on Hematite and Pyrite

2012 ◽  
Vol 1444 ◽  
Author(s):  
Jingjie Niu ◽  
Udo Becker ◽  
Rodney Ewing
Keyword(s):  
Charge Transfer ◽  
Co Adsorption ◽  
Reduction Rate ◽  
Mulliken Charge ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Initial Ph ◽  
Adsorption Reduction ◽  
Tapping Mode Afm

ABSTRACTUranyl adsorption/reduction by Fe2+ on hematite and pyrite has been studied at neutral pH under anoxic and CO2-free conditions. XPS results confirm that more U3O8 precipitates on hematite than on pyrite reacted for 24 h in 160 μM uranyl nitrate and 160 μM Fe2+ solution at initial pH 7.3. These results are explained in terms of co-adsorption energy and U atom Mulliken charge transfer by quantum mechanical calculations. Moreover, in situ fluid tapping-mode AFM experiments on hematite indicate a deceleration of the U reduction rate within 24 h due to the passivation of the surface caused by the formation of orthorhombic U3O8 crystals. In addition, crystals observed using AFM show morphologies of orthorhombic schoepite appearing on hematite after 5 h.

Co-adsorption of water and glycine on Cu{110}

2014 ◽  
Vol 16 (13) ◽  
pp. 6101 ◽  
Author(s):  
Marco Sacchi ◽  
Stephen J. Jenkins
Keyword(s):  
Co Adsorption ◽  
Adsorption Of Water

Competing routes for charge transfer in co-adsorption of K andO2on graphite

1993 ◽  
Vol 71 (4) ◽  
pp. 641-644 ◽  
Author(s):  
K. M. Hock ◽  
J. C. Barnard ◽  
R. E. Palmer ◽  
H. Ishida
Keyword(s):  
Charge Transfer ◽  
Co Adsorption

THEORETICAL INVESTIGATION OF O2 AND H2O CO-ADSORPTION ON CumCon(m+n=2∼7) CLUSTERS

2019 ◽  
Vol 26 (09) ◽  
pp. 1950064
Author(s):  
PEIYING HUO ◽  
XIURONG ZHANG ◽  
ZHICHENG YU ◽  
KUN GAO
Keyword(s):  
Charge Transfer ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Theoretical Study ◽  
Co Adsorption ◽  
Density Functional Method ◽  
Functional Method

A theoretical study was carried out of CumCon-O2-H2O ([Formula: see text]) clusters using density functional method. The results indicate that O2 and H2O molecules are adsorbed at top sites. The presence of H2O promotes more charge transfer to anti-bonding orbitals of O2 molecules which can lead to the elongation of O–O bond. And the effect of charge transfer suggests the occurrence of chemisorption. Comparison between CumCon-O2 and CumCon-O2-H2O, PDOS are also discussed.

First-principles study of nitrogen and carbon monoxide adsorptions on silicene

2016 ◽  
Vol 30 (25) ◽  
pp. 1650176 ◽  
Author(s):  
Shuying Zhong ◽  
Fanghua Ning ◽  
Fengya Rao ◽  
Xueling Lei ◽  
Musheng Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Charge Transfer ◽  
First Principles ◽  
Density Functional ◽  
Co Adsorption ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Adsorption Energies ◽  
Charge Calculations

Atomic adsorptions of N, C and O on silicene and molecular adsorptions of N2 and CO on silicene have been investigated using the density functional theory (DFT) calculations. For the atomic adsorptions, we find that the N atom has the most stable adsorption with a higher adsorption energy of 8.207 eV. For the molecular adsorptions, we find that the N2 molecule undergoes physisorption while the CO molecule undergoes chemisorption, the corresponding adsorption energies for N2 and CO are 0.085 and 0.255 eV, respectively. Therefore, silicene exhibits more reactivity towards the CO adsorption than the N2 adsorption. The differences of charge density and the integrated charge calculations suggest that the charge transfer for CO adsorption ([Formula: see text]0.015[Formula: see text]) is larger than that for N2 adsorption ([Formula: see text]0.005[Formula: see text]). This again supports that CO molecule is more active than N2 molecule when they are adsorbed onto silicene.

Reactivity of boron- and nitrogen-doped carbon nanotubes functionalized by (Pt, Eu) atoms toward O2 and CO: A density functional study

2016 ◽  
Vol 27 (07) ◽  
pp. 1650075 ◽  
Author(s):  
S. Abdel Aal
Keyword(s):  
Catalytic Activity ◽  
Charge Transfer ◽  
Density Functional ◽  
Co Adsorption ◽  
Energy Charge ◽  
Reduction Reaction ◽  
Functional Study ◽  
High Catalytic Activity ◽  
N Doping ◽  
Different Response

The adsorption behavior and electronic properties of CO and O2 molecules at the supported Pt and Eu atoms on (5,5) armchair SWCNT have been systematically investigated within density functional theory (DFT). Fundamental aspects such as adsorption energy, natural bond orbital (NBO), charge transfer, frontier orbitals and the projected density of states (PDOS) are elucidated to analyze the adsorption properties of CO and O2 molecules. The results reveal that B- and N-doping CNTs can enhance the binding strength and catalytic activity of Pt (Eu) anchored on the doped-CNT, where boron-doping is more effective. The electronic structures of supported metal are strongly influenced by the presence of gases. After adsorption of CO and O2, the changes in binding energy, charge transfer and conductance may lead to the different response in the metal-doped CNT-based sensors. It is expected that these results could provide helpful information for the design and fabrication of the CO and O2 sensing devices. The high catalytic activity of Pt supported at doped-CNT toward the interaction with CO and O2 may be attributed to the electronic resonance particularly among Pt-5d, CO-2[Formula: see text]* and O2-2[Formula: see text]* antibonding orbitals. In contrast to the supported Eu at doped-CNT, the Eu atom becomes more positively charged, which leads to weaken the CO adsorption and promote the O2 adsorption, consequently enhancing the activity for CO oxidation and alleviating the CO poisoning of the europium catalysts. A notable orbital hybridization and electrostatic interaction between these two species in adsorption process being an evidence of strong interaction. The electronic structure of O2 adsorbed on Eu-doped CNT resembles that of O[Formula: see text], therefore the transferred charge weakens the O–O bonds and facilitates the dissociation process, which is the precondition for the oxygen reduction reaction (ORR).

scholarly journals The impact of binary water-CO2 isotherm models on the optimal performance of sorbent-based direct air capture processes.

2021 ◽  
Author(s):  
John Young ◽  
Enrique García-Díez ◽  
Susana Garcia ◽  
Mijndert van der Spek
Keyword(s):  
Energy Consumption ◽  
Co Adsorption ◽  
Process Modelling ◽  
Optimal Performance ◽  
Isotherm Models ◽  
Capture Process ◽  
Direct Air Capture ◽  
Air Capture ◽  
Adsorption Of Water ◽  
The Impact

First, an investigation of the co-adsorption of water and CO<sub>2</sub> onto a benchmark amine-functionalised adsorbent. Following on from this is a detailed process modelling and optimisation study of this sorbents performance in a direct air capture process. Next is a demonstration how the results are affected by the co-adsorption descriptions. Finally, a comparison between the modelled direct air capture process to existing and literature processes to benchmark the energy consumption of direct air capture.

scholarly journals Polydimethyl siloxane/MIL-101 Composites for Enhanced Toluene Adsorption in the Presence of Humidity

2021 ◽  
Author(s):  
Luqman Hakim Mohd Azmi ◽  
Pavani Cherukupally ◽  
Elwin Hunter-Sellars ◽  
Bradley P. Ladewig ◽  
Daryl R. Williams
Keyword(s):  
Vapor Phase ◽  
Co Adsorption ◽  
Deposition Process ◽  
Polydimethyl Siloxane ◽  
Hydrophobicity Index ◽  
Molecular Weights ◽  
Adsorbent Regeneration ◽  
Adsorption Of Water ◽  
And Performance ◽  
The Stability

<div><b>ABSTRACT</b> <br></div><div><br></div><div> Competition between atmospheric moisture and volatile organic compounds (VOCs) for an adsorbent’s sites can significantly impact its VOC removal efficiency. The development of moisture-tolerant adsorbents is essential to address this issue. A vapor phase deposition process using polydimethylsiloxane (PDMS) has created a hydrophobic form of the highly porous, normally hydrophilic, MOF MIL-101. After optimizing the PDMS vapor deposition time and molecular weights, hydrophobicity index calculations verified the improved hydrophobicity of the coated MOF (MIL-PDMS-Sigma-0.25) over its pristine form. The surface area, pore volume as well as single component vapor adsorption of water and toluene capacities were also preserved, resulting to similar performance to MIL-101. Toluene-water vapor co-adsorption experiments were conducted at 40% RH using two toluene concentrations: 0.5% P/P<sub>0</sub> and 10% P/P<sub>0</sub>, mimicking environmental VOC and industrial concentrations, respectively. At 0.5% P/P<sub>0</sub>, MIL-PDMS-Sigma-0.25 exhibited 60% higher adsorption capacity and twice the rate of toluene capture relative to pristine MIL-101, as well as a 3-fold higher toluene uptake relative to a commercial activated carbon. Preliminary adsorbent regeneration experiments confirm the stability and performance of MIL-PDMS-Sigma-0.25. Using a simple vapor phase modification, this new MOF-composite material offers superior competitive toluene vapor uptake in humidified real-world conditions at VOC concentrations. </div>

Unveiling CO adsorption on Cu surfaces: new insights from molecular orbital principles

2018 ◽  
Vol 20 (40) ◽  
pp. 25892-25900 ◽  
Author(s):  
Kareem M. Gameel ◽  
Icell M. Sharafeldin ◽  
Amr U. Abourayya ◽  
Ahmed H. Biby ◽  
Nageh K. Allam
Keyword(s):  
Charge Transfer ◽  
Molecular Orbital ◽  
Structural Changes ◽  
Co Adsorption ◽  
Adsorption Site ◽  
Surface Type ◽  
Adsorption Mechanisms ◽  
Holistic Analysis ◽  
Adsorption Energies

A holistic analysis of adsorption energies, charge transfer, and structural changes has been employed to highlight the variations in adsorption mechanisms upon changing the surface type and the adsorption site.

Adsorption of Gaseous Propylamine on Films of Polypyrrole in Different Oxidation States

1999 ◽  
Vol 64 (1) ◽  
pp. 1-12
Author(s):  
Vítězslav Papež ◽  
Šárka Brodská ◽  
Jan Langmaier ◽  
Zdeněk Samec ◽  
Karin Potje-Kamloth
Keyword(s):  
Work Function ◽  
Gas Phase ◽  
Quartz Crystal ◽  
Co Adsorption ◽  
Polymer Surface ◽  
Water Layer ◽  
Acetonitrile Solution ◽  
Water Vapour Pressure ◽  
Kelvin Probe ◽  
Adsorption Of Water

Quartz crystal microbalance and Kelvin probe were used to investigate the interaction between propylamine (PrNH2) vapour and polypyrrole (PPy) films. The films were prepared by oxidative electropolymerization of pyrrole on a platinum electrode in acetonitrile solution. The nature of interaction is strongly influenced by the oxidation state of the film and co-adsorption of water. On the surface of the oxidized PPy, water adsorbs to form a multilayer. The work function increase of the Pt/PPy electrode exposed to both water and PrNH2 vapoures was attributed to the PrNH2 dissolution and dissociation within the water layer followed by the formatted PrNH3+ cation adsorption on the liquid surface with the alkyl group facing the gas phase. On the contrary, the water adsorption on the reduced PPy is rather weak and the work function decrease observed at the PrNH2 exposure might be connected with the neutral molecules adsorption directly on the polymer surface. The water co-adsorption is documented by a drop in the adsorption of PrNH2 upon lowering the water vapour pressure in the gas phase.

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