scholarly journals Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core–shell structure

RSC Advances ◽  
2019 ◽  
Vol 9 (20) ◽  
pp. 11377-11384 ◽  
Author(s):  
Kaili Wei ◽  
Baolai Wang ◽  
Jiamin Hu ◽  
Fuming Chen ◽  
Qing Hao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Conduction Band ◽  
Shell Structure ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Core Shell ◽  
Valence Band Edge ◽  
Core Shell Structure ◽  
Positive Valence

It's highly desired to design an effective Z-scheme photocatalyst with excellent charge transfer and separation, a more negative conduction band edge (ECB) than O2/·O2− (−0.33 eV) and a more positive valence band edge (EVB) than ·OH/OH− (+2.27 eV).

scholarly journals A SERS Study of Charge Transfer Process in Au Nanorod–MBA@Cu2O Assemblies: Effect of Length to Diameter Ratio of Au Nanorods

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 867
Author(s):  
Lin Guo ◽  
Zhu Mao ◽  
Sila Jin ◽  
Lin Zhu ◽  
Junqi Zhao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Shell Structure ◽  
Shell Structures ◽  
Core Shell ◽  
Absorption Bands ◽  
Au Nanorods ◽  
The Core ◽  
Band Position ◽  
Surface Enhanced Raman ◽  
Core Shell Structure

Surface-enhanced Raman scattering (SERS) is a powerful tool in charge transfer (CT) process research. By analyzing the relative intensity of the characteristic bands in the bridging molecules, one can obtain detailed information about the CT between two materials. Herein, we synthesized a series of Au nanorods (NRs) with different length-to-diameter ratios (L/Ds) and used these Au NRs to prepare a series of core–shell structures with the same Cu2O thicknesses to form Au NR–4-mercaptobenzoic acid (MBA)@Cu2O core–shell structures. Surface plasmon resonance (SPR) absorption bands were adjusted by tuning the L/Ds of Au NR cores in these assemblies. SERS spectra of the core-shell structure were obtained under 633 and 785 nm laser excitations, and on the basis of the differences in the relative band strengths of these SERS spectra detected with the as-synthesized assemblies, we calculated the CT degree of the core–shell structure. We explored whether the Cu2O conduction band and valence band position and the SPR absorption band position together affect the CT process in the core–shell structure. In this work, we found that the specific surface area of the Au NRs could influence the CT process in Au NR–MBA@Cu2O core–shell structures, which has rarely been discussed before.

Valence Band Edge Shifts and Charge-transfer Dynamics in Li-Doped NiO Based p-type DSSCs

2016 ◽  
Vol 188 ◽  
pp. 309-316 ◽  
Author(s):  
Lifang Wei ◽  
Linpeng Jiang ◽  
Shuai Yuan ◽  
Xin Ren ◽  
Yin Zhao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Valence Band ◽  
Band Edge ◽  
Valence Band Edge ◽  
Charge Transfer Dynamics ◽  
P Type

scholarly journals Theoretical investigation on $$\hbox {BeN}_{{2}}$$ monolayer for an efficient bifunctional water splitting catalyst

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. R. Ashwin Kishore ◽  
R. Varunaa ◽  
Amirhossein Bayani ◽  
Karin Larsson
Keyword(s):  
Water Splitting ◽  
Valence Band ◽  
Conduction Band ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Substantial Impact ◽  
Solar Hydrogen Production

AbstractThe search for an active, stable, and abundant semiconductor-based bifunctional catalysts for solar hydrogen production will make a substantial impact on the sustainable development of the society that does not rely on fossil reserves. The photocatalytic water splitting mechanism on a $$\hbox {BeN}_{{2}}$$ BeN 2 monolayer has here been investigated by using state-of-the-art density functional theory calculations. For all possible reaction intermediates, the calculated changes in Gibbs free energy showed that the oxygen evolution reaction will occur at, and above, the potential of 2.06 V (against the NHE) as all elementary steps are exergonic. In the case of the hydrogen evolution reaction, a potential of 0.52 V, or above, was required to make the reaction take place spontaneously. Interestingly, the calculated valence band edge and conduction band edge positions for a $$\hbox {BeN}_{{2}}$$ BeN 2 monolayer are located at the potential of 2.60 V and 0.56 V, respectively. This indicates that the photo-generated holes in the valence band can oxidize water to oxygen, and the photo-generated electrons in the conduction band can spontaneously reduce water to hydrogen. Hence, the results from the present theoretical investigation show that the $$\hbox {BeN}_{{2}}$$ BeN 2 monolayer is an efficient bifunctional water-splitting catalyst, without the need for any co-catalyst.

Electronic States in the Gap of a-Si from Bond Angle Variations

1990 ◽  
Vol 192 ◽  
Author(s):  
B. N. Davidson ◽  
G. Lucovsky
Keyword(s):  
Valence Band ◽  
Density Of States ◽  
Bond Angle ◽  
Bethe Lattice ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
Defect States ◽  
Discrete State ◽  
Bond Angles

ABSTRACTWe investigate the formation of defect states in the gap of a-Si arising from deviations from the ideal tetrahedral bond angles. The local density of states for Si atoms in disordered environments is calculated using tight-binding parameters for the cluster-Bethe lattice method. The Hamiltonian for a-Si with bond angle distortions is taken as an average over many configurations associated with a random choice of bond angles, weighted by Gaussian distributions with standard deviations between 2°.and 10°. Bond angle deviations in this range generate a density of defect states at the valence band edge that: 1) increases as the average bond angle deviation increases; and 2) is significantly larger than the density of band tail states generated at the conduction band edge. We obtain a shift of the absorption edge from the joint density of states (DOS) as a function of bond angle deviations. In addition, a calculation of the DOS for a distorted tetrahedral cluster embedded in an idealized Bethe lattice yields a threshold bond angle distortion of ±20° for the appearance of a discrete state in the gap near the valence band edge.

Visible Light Activity in Phenol Degradation of C60@P25 Photocatalyst with Core–Shell Structure

2020 ◽  
Vol 15 (2) ◽  
pp. 189-196
Author(s):  
Ming-Guang Ma ◽  
Yun-Xia Wei ◽  
Sheng-Ying Li ◽  
Fang Liu ◽  
Guo-Hu Zhao
Keyword(s):  
Visible Light ◽  
Conduction Band ◽  
Hydroxyl Radicals ◽  
Shell Structure ◽  
Apparent Rate Constant ◽  
Phenol Degradation ◽  
Core Shell ◽  
Photogenerated Electrons ◽  
Light Activity ◽  
Core Shell Structure

C60@P25 photocatalyst with core–shell structure was synthesized by adsorption methods. Under visible light irradiation, the electrons of the excited C60 (C*60) adsorbed on the surface of P25can be injected into the conduction band of the P25. The electrons could combine with O2 easily, which promotes the formation of hydroxyl radicals which contributes to the dramatic visible light activity of C60@P25 photocatalyst in phenol degradation. The apparent rate constant of C60@P25 photocatalyst in phenol degradation is almost 3.3 times of which of P25. At the same time, the phenol can be mineralized completely. Under UV irradiation, the photogenerated electrons on the conduction band of P25 can be injected into the LUMO orbit of C60, which is too low that electrons could not combine with O2 easily, interdicting the formation of hydroxyl radicals, resulting in the decrease of photoactivity and weakening in the mineralization of phenol.

Synthesis and Characterization of CdSe/CdS Core-Shell and CdSe/CdS Composites

1999 ◽  
Vol 581 ◽  
Author(s):  
M. Azad Malika ◽  
Paul O'Brien ◽  
N. Revaprasaduac
Keyword(s):  
Absorption Band ◽  
Shell Structure ◽  
Band Edge ◽  
Spherical Particles ◽  
Core Shell ◽  
Band Edge Emission ◽  
Absorption Band Edge ◽  
Emission Maximum ◽  
Core Shell Structure ◽  
Average Size

ABSTRACTHighly mono-dispersed CdSe/CdS core-shell and CdSe/CdS composites have been prepared by a novel route involving thermolysis in TOPO using Cd(Se2CNMe(nHex))2 and Cd(S2CNMe(nHex))2. The absorption band edge (652 nm, 1.90 eV) of the CdSe-CdS core-shell structure is red shifted (22 nm, 0.0 17 eV) as compared to the CdSe nanoparticles (630 nm, 1.96 eV) whereas the absorption spectrum of the CdSe-CdS composites shows the absorption band edge at (584 nm, 2.12 eV), blue shifted (46 nm, 0.037 eV) as expected. Photoluminescence (PL, λex = 400 nm) of both the core-shell (622 nm) and the composites (588 nm) show values close to band edge emission. A sharper emission maximum with a considerable increase of intensity is observed for core-shell structure as compared to that of CdSe whereas the composite showed a broader emission maximum. The TEM images of the CdSe/CdS core-shell nanoparticles show crystalline, spherical particles with the average size of 53 Å (±7 %), a increase of 8 Å than the average size of CdSe (45 Å) nanoparticles, with a narrow size distribution. The High Resolution Transmission Electron Microscopy (HRTEM) showed lattice spacing intermediate between those for CdSe and CdS as is observed by Selected Area Electron Diffraction (SAED) and X-ray patterns (hexagonal phase). As expected no interface can be observed by HRTEM between CdSe core and CdS shell. The TEM image of the CdSe-CdS composites show particles with an average size of 48.7 Å (±10%).

A CoSe–C@C core–shell structure with stable potassium storage performance realized by an effective solid electrolyte interphase layer

2021 ◽  
Author(s):  
Xin Gu ◽  
Li Zhang ◽  
Wenchao Zhang ◽  
Sailin Liu ◽  
Sheng Wen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Shell Structure ◽  
Solid Electrolyte Interphase ◽  
Inorganic Compound ◽  
Core Shell ◽  
Ion Diffusion ◽  
Storage Performance ◽  
Sei Layer ◽  
Core Shell Structure ◽  
Charge Transfer Dynamics

A CoSe–C@C core–shell structure is designed as a novel potential anode for PIBs. The introduction of KFSI salt is found to contribute to the formation of an inorganic-compound-rich SEI layer, benefiting the K ion diffusion and charge transfer dynamics.

Where Would the Electronic States of a Small Graphite-Like Carbon Island Contribute to the SiC/SiO2 Interface State Density Distribution?

2006 ◽  
Vol 527-529 ◽  
pp. 1019-1022 ◽  
Author(s):  
Christoph Thill ◽  
Jan Knaup ◽  
Peter Deák ◽  
Thomas Frauenheim ◽  
Wolfgang J. Choyke
Keyword(s):  
Conduction Band ◽  
Electronic States ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Valence Band Edge ◽  
High Resolution Microscopy ◽  
Experimental Detection Limit

The high density of interface electron traps in the SiC/SiO2 system, near the conduction band of 4H-SiC, is often ascribed to graphitic carbon islands at the interface, although such clusters could not be detected by high resolution microscopy. We have calculated the electronic structure of a model interface containing a small graphite-like precipitate of 19 carbon atoms, with a diameter of ~7 Å, corresponding to the experimental detection limit. The analysis of the density of states shows only occupied states in the band gap of 4H-SiC near the valence band edge, while carbon related unoccupied states appear only well above the conduction band edge.

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