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

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.

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).

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.

scholarly journals Effects of co-adsorption on interfacial charge transfer in a quantum dot@dye composite

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Peng Cui ◽  
Yuan Xue
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Quantum Dot ◽  
Charge Separation ◽  
Density Functional ◽  
Co Adsorption ◽  
Hole Transfer ◽  
Interfacial Charge Transfer ◽  
Efficient Charge ◽  
Interfacial Charge

AbstractThe sensitive electronic environment at the quantum dot (QD)–dye interface becomes a roadblock to enhancing the energy conversion efficiency of dye-functionalized quantum dots (QDs). Energy alignments and electronic couplings are the critical factors governing the directions and rates of different charge transfer pathways at the interface, which are tunable by changing the specific linkage groups that connect a dye to the QD surface. The variation of specific anchors changes the binding configurations of a dye on the QD surface. In addition, the presence of a co-adsorbent changes the dipole–dipole and electronic interactions between a QD and a dye, resulting in different electronic environments at the interface. In the present work, we performed density functional theory (DFT)-based calculations to study the different binding configurations of N719 dye on the surface of a Cd33Se33 QD with a co-adsorbent D131 dye. The results revealed that the electronic couplings for electron transfer were greater than for hole transfer when the structure involved isocyanate groups as anchors. Such strong electronic couplings significantly stabilize the occupied states of the dye, pushing them deep inside the valence band of the QD and making hole transfer in these structures thermodynamically unfavourable. When carboxylates were involved as anchors, the electronic couplings for hole transfer were comparable to electron transfer, implying efficient charge separation at the QD–dye interface and reduced electron–hole recombination within the QD. We also found that the electronic couplings for electron transfer were larger than those for back electron transfer, suggesting efficient charge separation in photoexcited QDs. Overall, the current computational study reveals some fundamental aspects of the relationship between the interfacial charge transfer for QD@dye composites and their morphologies which benefit the design of QD-based nanomaterials for photovoltaic applications.

Study of charge transfer in FeTi

1983 ◽  
Vol 41 ◽  
pp. 296-297
Author(s):  
J. Taft∅
Keyword(s):  
Charge Transfer ◽  
Charge Distribution ◽  
Electron Scattering ◽  
Periodic System ◽  
Electron Distribution ◽  
Scattering Amplitude ◽  
Transition Elements ◽  
Hartree Fock ◽  
Cscl Structure ◽  
The Right

It is well known that for reflections corresponding to large interplanar spacings (i.e., sin θ/λ small), the electron scattering amplitude, f, is sensitive to the ionicity and to the charge distribution around the atoms. We have used this in order to obtain information about the charge distribution in FeTi, which is a candidate for storage of hydrogen. Our goal is to study the changes in electron distribution in the presence of hydrogen, and also the ionicity of hydrogen in metals, but so far our study has been limited to pure FeTi. FeTi has the CsCl structure and thus Fe and Ti scatter with a phase difference of π into the 100-ref lections. Because Fe (Z = 26) is higher in the periodic system than Ti (Z = 22), an immediate “guess” would be that Fe has a larger scattering amplitude than Ti. However, relativistic Hartree-Fock calculations show that the opposite is the case for the 100-reflection. An explanation for this may be sought in the stronger localization of the d-electrons of the first row transition elements when moving to the right in the periodic table. The tabulated difference between fTi (100) and ffe (100) is small, however, and based on the values of the scattering amplitude for isolated atoms, the kinematical intensity of the 100-reflection is only 5.10-4 of the intensity of the 200-reflection.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

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