scholarly journals Silver Quantum Dot Decorated 2D-SnO2 Nanoflakes for Photocatalytic Degradation of the Water Pollutant Rhodamine B

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1536 ◽  
Author(s):  
Nadavala Siva Kumar ◽  
Mohammad Asif ◽  
T. Ranjeth Kumar Reddy ◽  
Gnanendra Shanmugam ◽  
Abdelhamid Ajbar
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Rhodamine B ◽  
Large Scale ◽  
Volume Ratio ◽  
Plasmonic Effect ◽  
Electron Hole ◽  
Semiconductor Structures ◽  
Photocatalytic Application ◽  
Water Pollutant

Decoration of 2D semiconductor structures with heterogeneous metal quantum dots has attracted considerable attention due to advanced optical, electrical, and catalytic properties that result from the large surface-to-volume ratio associated with these structures. Herein, we report on silver quantum dot decorated 2D SnO2 nanoflakes for the photocatalytic abatement of water effluents, the synthesis of which was achieved through a straightforward and mild hydrothermal procedure. The photocatalysts were systematically investigated using UV–Vis, XRD, electron microscopy (SEM, HR-TEM), EDX, XPS and FTIR. The photocatalytic activity of the nanostructures was evaluated for the abatement of water pollutant rhodamine B (RhB), under light irradiation. The mild hydrothermal synthesis (100 °C) proved highly efficient for the production of large scale Ag quantum dot (QD)/SnO2 nanoflakes for a novel photocatalytic application. The decoration of SnO2 with Ag QDs significantly enhances the synergetic charge transfer, which diminishes the photo-induced electron-hole reunion. Moreover, the plasmonic effect from Ag QDs and 2D-SnO2 structures acts as an electron tank to collect the photo-induced electrons, generating a Schottky barrier between the SnO2 structures and quantum dots. Overall, this resulted in a facile and efficient degradation of RhB, with a rate double that of pristine SnO2.

Charge Separation Between Strain Coupled Quantum Dots in a Self-Assembled InAs Quantum Dot Structure

1999 ◽  
Vol 571 ◽  
Author(s):  
W. V. Schoenfeld ◽  
T. Lundstrom ◽  
P. M. Petroff
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Preliminary Data ◽  
Charge Separation ◽  
Electron Hole ◽  
Coupled Quantum Dots ◽  
Time Resolved ◽  
Inas Quantum Dot ◽  
Storage Times ◽  
Time Resolved Photoluminescence

ABSTRACTWe present an InAs QDs structure designed to separate and store photo-generated electron-hole pairs. Charge separation in the structure is demonstrated using power dependent photoluminescence and biased photoluminescence. Preliminary data from time resolved photoluminescence suggest storage times in the device in the μsec range.

Simple Fabrication of High Density Quantum Dot Arrays Using Anodic Aluminum Oxide Mask

2004 ◽  
Vol 818 ◽  
Author(s):  
Joon-Ho Sung ◽  
Heesung Moon ◽  
Jae Ho Bahng ◽  
Ja-Yong Koo ◽  
Bongsoo Kim
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Anodic Aluminum Oxide ◽  
Large Scale ◽  
Porous Alumina ◽  
High Density ◽  
Alumina Template ◽  
Anodic Aluminum ◽  
Porous Alumina Template ◽  
Pore Widening

AbstractWe fabricated quantum dot arrays using anodic alumina mask. We grew an alumina template on Si wafers by two-step anodization. The porous alumina template thus grown is used as a mask for metal deposition. After thermal evaporation and removal of the mask, we fabricated the quantum dot arrarys on a Si substrate. Using this template-assisted method we obtained a high density array of quantum dots in a large scale. These quantum dots have a narrow size distribution which can be easily controlled by a pore widening of templates from 20 to 60 nm.

scholarly journals A Transfer Hamiltonian Model for Devices Based on Quantum Dot Arrays

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
S. Illera ◽  
J. D. Prades ◽  
A. Cirera ◽  
A. Cornet
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Random Distribution ◽  
Rate Equations ◽  
Electron Hole ◽  
Fundamental Parameters ◽  
Transmission Coefficients ◽  
Consistent Field ◽  
Hamiltonian Model ◽  
Self Consistent Field

We present a model of electron transport through a random distribution of interacting quantum dots embedded in a dielectric matrix to simulate realistic devices. The method underlying the model depends only on fundamental parameters of the system and it is based on the Transfer Hamiltonian approach. A set of noncoherent rate equations can be written and the interaction between the quantum dots and between the quantum dots and the electrodes is introduced by transition rates and capacitive couplings. A realistic modelization of the capacitive couplings, the transmission coefficients, the electron/hole tunneling currents, and the density of states of each quantum dot have been taken into account. The effects of the local potential are computed within the self-consistent field regime. While the description of the theoretical framework is kept as general as possible, two specific prototypical devices, an arbitrary array of quantum dots embedded in a matrix insulator and a transistor device based on quantum dots, are used to illustrate the kind of unique insight that numerical simulations based on the theory are able to provide.

Removal of Rhodamine B from water by using CdTeSe quantum dot-cellulose membrane composites

RSC Advances ◽  
2016 ◽  
Vol 6 (22) ◽  
pp. 18549-18557 ◽  
Author(s):  
Canan Baslak ◽  
Gulsin Arslan ◽  
Mahmut Kus ◽  
Yunus Cengeloglu
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Rhodamine B ◽  
Facilitated Transport ◽  
Cellulose Membrane ◽  
Inclusion Membrane ◽  
Polymer Inclusion Membrane

Facilitated transport of Rhodamine B through a novel polymer inclusion membrane (PIM) containing CdTeSe Quantum Dots (QDs) as a carrier reagent has been investigated.

Solar Cells Based on Quantum Dots: Multiple Exciton Generation and Intermediate Bands

MRS Bulletin ◽  
2007 ◽  
Vol 32 (3) ◽  
pp. 236-241 ◽  
Author(s):  
Antonio Luque ◽  
Antonio Martí ◽  
Arthur J. Nozik
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Quantum Dot ◽  
Single Photon ◽  
Quantum Yields ◽  
Bandgap Energy ◽  
Hot Electron ◽  
Electron Hole ◽  
Multiple Exciton Generation ◽  
Intermediate Band

AbstractSemiconductor quantum dots may be used in so-called third-generation solar cells that have the potential to greatly increase the photon conversion efficiency via two effects: (1) the production of multiple excitons from a single photon of sufficient energy and (2) the formation of intermediate bands in the bandgap that use sub-bandgap photons to form separable electron–hole pairs. This is possible because quantization of energy levels in quantum dots produces the following effects: enhanced Auger processes and Coulomb coupling between charge carriers; elimination of the requirement to conserve crystal momentum; slowed hot electron–hole pair (exciton) cooling; multiple exciton generation; and formation of minibands (delocalized electronic states) in quantum dot arrays. For exciton multiplication, very high quantum yields of 300–700% for exciton formation in PbSe, PbS, PbTe, and CdSe quantum dots have been reported at photon energies about 4–8 times the HOMO–LUMO transition energy (quantum dot bandgap), respectively, indicating the formation of 3–7 excitons/photon, depending upon the photon energy. For intermediate-band solar cells, quantum dots are used to create the intermediate bands from the con fined electron states in the conduction band. By means of the intermediate band, it is possible to absorb below-bandgap energy photons. This is predicted to produce solar cells with enhanced photocurrent without voltage degradation.

Hydrothermal Synthesis and Photocatalytic Performance of Ag Quantum Dots Sensitized Bi4Ti3O12 Nanobelts

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550020 ◽  
Author(s):  
Xue Lin ◽  
Xiaoyu Guo ◽  
Di Liu ◽  
Qingwei Wang ◽  
Yongsheng Yan
Keyword(s):  
Quantum Dots ◽  
Photocatalytic Activity ◽  
Rhodamine B ◽  
High Photocatalytic Activity ◽  
Contact Interface ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Intimate Contact ◽  
Composite Photocatalyst ◽  
Hole Recombination

Ag / Bi 4 Ti 3 O 12 heterostructure with high photocatalytic activity was synthesized via a simple and practical hydrothermal method by using Bi 4 Ti 3 O 12 nanobelts as substrate materials. The as-prepared Ag / Bi 4 Ti 3 O 12 heterostructure included Ag quantum dots assembling uniformly on the surface of Bi 4 Ti 3 O 12 nanobelts. Comparing with pure Bi 4 Ti 3 O 12 nanobelts, the composite photocatalyst exhibited enhanced photocatalytic activity under visible light irradiation in the decomposition of rhodamine B aqueous solution. The enhancement performance is believed to be induced by the intimate contact interface, where silver quantum dots serve as good electron acceptor for facilitating quick photoexcited electron transfer and thus decreasing electron-hole recombination. It was also found that the photodegradation of rhodamine B molecules is mainly attributed to the oxidation action of the generated [Formula: see text] radicals.

Nanostructure of semiconductor quantum dots in a borosilicate glass matrix by complementary use of HREM and AEM

1990 ◽  
Vol 48 (4) ◽  
pp. 728-729
Author(s):  
M.J. Kim ◽  
L.C. Liu ◽  
S.H. Risbud ◽  
R.W. Carpenter
Keyword(s):  
Quantum Dots ◽  
Borosilicate Glass ◽  
Glass Matrix ◽  
Optical Switching ◽  
Response Times ◽  
Fast Response ◽  
Processing Technique ◽  
Internal Stresses ◽  
Electron Hole ◽  
Spatial Dimensions

When the size of a semiconductor is reduced by an appropriate materials processing technique to a dimension less than about twice the radius of an exciton in the bulk crystal, the band like structure of the semiconductor gives way to discrete molecular orbital electronic states. Clusters of semiconductors in a size regime lower than 2R {where R is the exciton Bohr radius; e.g. 3 nm for CdS and 7.3 nm for CdTe) are called Quantum Dots (QD) because they confine optically excited electron- hole pairs (excitons) in all three spatial dimensions. Structures based on QD are of great interest because of fast response times and non-linearity in optical switching applications.In this paper we report the first HREM analysis of the size and structure of CdTe and CdS QD formed by precipitation from a modified borosilicate glass matrix. The glass melts were quenched by pouring on brass plates, and then annealed to relieve internal stresses. QD precipitate particles were formed during subsequent "striking" heat treatments above the glass crystallization temperature, which was determined by differential thermal analysis.

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

scholarly journals Preparation and Photocatalytic Performance for Degradation of Rhodamine B of AgPt/Bi4Ti3O12 Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2206
Author(s):  
Gaoqian Yuan ◽  
Gen Zhang ◽  
Kezhuo Li ◽  
Faliang Li ◽  
Yunbo Cao ◽  
...  
Keyword(s):  
Visible Light ◽  
Noble Metal ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Bimetallic Nanoparticles ◽  
Resonance Effect ◽  
Visible Region ◽  
Photogenerated Electron ◽  
Pt Nanoparticles ◽  
Electron Hole

Loading a noble metal on Bi4Ti3O12 could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In this paper, AgPt/Bi4Ti3O12 composite photocatalysts were prepared using the photoreduction method, and the effects of the type and content of noble metal on the photocatalytic performance of the catalysts were investigated. The photocatalytic degradation of rhodamine B (RhB) showed that the loading of AgPt bimetallic nanoparticles significantly improved the catalytic performance of Bi4Ti3O12. When 0.10 wt% noble metal was loaded, the degradation rate for RhB of Ag0.7Pt0.3/Bi4Ti3O12 was 0.027 min−1, which was respectively about 2, 1.7 and 3.7 times as that of Ag/Bi4Ti3O12, Pt/Bi3Ti4O12 and Bi4Ti3O12. The reasons may be attributed as follows: (i) the utilization of visible light was enhanced due to the surface plasmon resonance effect of Ag and Pt in the visible region; (ii) Ag nanoparticles mainly acted as electron acceptors to restrain the recombination of photogenerated electron-hole pairs under visible light irradiation; and (iii) Pt nanoparticles acted as electron cocatalysts to further suppress the recombination of photogenerated electron-hole pairs. The photocatalytic performance of Ag0.7Pt0.3/Bi4Ti3O12 was superior to that of Ag/Bi4Ti3O12 and Pt/Bi3Ti4O12 owing to the synergistic effect between Ag and Pt nanoparticles.

Sign in / Sign up

Export Citation Format

Share Document