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INTRODUCTION: Cadmium sulfides (CdS) are regarded as a prominent class of
broadband-emitting nanoparticles and contain a direct band gap of 2
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It has
been widely used in light-emitting diodes for flat panel displays and chiefly in photo
chrome–fluorophore assemblage as fluorophores in solar cells [5] CdS Quantum
Dots are the inorganic semiconductors that belong to the cadmium chalcogenide
family
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The Bohr radius of CdS
particles is 5
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CdS nanoparticles or particles with a size smaller than 5
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CdS QDs show 3D
quantum confinement due to their distinct energy levels
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As a result of this quantum confinement, in CdS QDs, the
photoluminescence emission spectrum and the phosphorescence emission
spectrum are produced, which show a sharp and narrow peak, due to the discrete
electronic transitions
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The observation of both photoluminescence and phosphorescence emission spectra
for CdS QDs can provide valuable information about the electronic structure, size,
and properties of the QDs
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The bandgap of bulk CdS is around 2
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Therefore, the absorption peak of bulk CdS is usually
observed in the ultraviolet to the blue region of the electromagnetic spectrum,
around 525-550 nm
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As a result, the absorption peak of CdS QDs is
typically observed in the blue to an ultraviolet region of the electromagnetic
spectrum, around 375-425 nm
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5 eV, which means that they absorb light in the
ultraviolet region of the electromagnetic spectrum
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4 eV, which means that they
absorb light in the blue-green region of the electromagnetic spectrum
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1
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2
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CdS QDs can be synthesized in different crystalline structures, including the facecentered cubic (FCC), hexagonal close-packed (HCP), and wurtzite structures
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Among these wet chemicals, the method is the most
commonly used technique
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They are inexpensive, take less time, and are less hazardous as

compared to other techniques
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CdS QDs have a wide range of potential applications due to their
unique optical and electronic properties
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They have potential applications in imaging,
diagnostics, and therapeutics
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CdS QDs have
potential applications in optoelectronic devices, such as light-emitting diodes (LEDs),
due to their ability to emit light and their high quantum efficiency
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They can be used as photocatalysts to
degrade organic pollutants, such as dyes or pesticides, under visible light irradiation
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CdS QDs can be used as
quantum dots for quantum computing due to their discrete energy levels and ability
to store and manipulate information at the nanoscale
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CdS QDs can release
toxic cadmium ions, which can lead to environmental and health risks
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Some commonly used sources of sulfur for CdS nanoparticle
synthesis include --1
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Sodium sulfide (Na2S)
3
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Hydrogen sulfide (H2S) gas
5
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In the synthesis of CdS
nanoparticles, elemental sulfur is typically reacted with a cadmium source, such as
cadmium acetate, in the presence of a reducing agent and a stabilizing agent
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In this method, Na2S is typically
used as a sulfur source in the reaction with a cadmium precursor, resulting in the

formation of CdS nanoparticles
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Hydrogen sulfide (H2S) gas: H2S can be used as a sulfur source for the synthesis of
CdS nanoparticles in a gas-phase reaction
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The synthesis of high-quality CdS nanocrystals is an active area of research, and
several methods have been developed to achieve this goal such as —
1
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Thermolysis of single precursors at relatively high temperatures
3
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Different types of preparation methods have been developed to control the size
of semiconductor nanocrystals, including cadmium sulfide (CdS) nanocrystals —
a) Size-selective chromatography
b) Size fractionation by exclusion chromatography
c) Stabilizers and polymer
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The two polymorphs have different crystal structures, which affect
their electronic band structures and optical properties
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And the hexagonal form of CdS has a lower
symmetry, which results in a lower density of states at the band edges and a
narrower bandgap
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The hexagonal phase is
thermodynamically stable, which means it has lower free energy than the cubic
phase under normal conditions and the cubic phase of CdS is metastable, which
means that it is not the preferred phase under normal conditions but can be
stabilized under certain conditions
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1155/2009/914501]
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Generally, the

controlled colloid precipitation method is a common approach used for synthesizing
CdS nanoparticles
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In earlier studies, researchers have
explored the use of high-temperature and organic capping agents in the synthesis of
CdS quantum dots
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While organic capping
agents can reduce the formation of surface defects and passivate the surface of
CdS quantum dots, which can improve their photoluminescence properties
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1039/b412317d]
Cadmium sulfide (CDS) QDs, which have a direct band gap of 2
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They have
recently been recognized as an emerging class of broad-band radiating
nanoparticles
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The production of CdS NPs by certain bacteria in the presence of Cd2+ and sulfate
anions has been demonstrated
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To produce semiconductor nanocrystals with new
properties, extremophiles have specifically been suggested as an option
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Atoms from elements in groups II to VI, III to V, or IV to VI of the periodic table are
used to create quantum dots
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Cadmium Sulfide (CdS)
Quantum Dots (QDs) are indeed widely researched QDs, these QDs are made up of
group II-VI semiconductor materials with Cadmium (Cd) as the group II element and
Sulfur (S) as the group VI element
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Numerous research studies have been conducted on these QDs, and the
information can be acquired from several sources
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Fluorescence
sensors for metal ion-sensing applications frequently use Cds QDs (Cadmium
Sulfide Quantum Dots )
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Due to their reasonable stability, strong conversion efficiency, and ease of
fabrication, cadmium sulfide-based quantum dots have recently grown in popularity
as nanoparticles with a promise for use in biosensing applications
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An electrochemical biosensor with a detection limit of 0
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It is based on
reduced graphene oxide (rGO) and cadmium sulfide quantum dots (CdSQDs)
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conducted more research on the optical sensor
based on reduced graphene oxide (rGO)/cadmium sulfide quantum dots (CdSQDs)
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1 PM
with a binding affinity of 0
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Thus, a unique nanocomposite of CdSQDspolyamidoamine (PAMAM) dendrimers was created [8] to fully use semiconductor
quantum dots
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Yadav, C
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 Synthesis of CdS Quantum Dots
Temperatures (Doctoral dissertation, Sharda University)
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Rempel’, S
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, Razvodov, A
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, Nebogatikov, M
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, Shishkina, E
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, Shur, V
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,
& Rempel’, A
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(2013)
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 Physics of the Solid State, 55, 624-628
3
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L
...
M
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, Assouar, M
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, Rinnert, H
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(2009)
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 Journal of
Nanomaterials, 2009, 1-9
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Li, Y
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C
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, Pickett, N
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J
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S
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&
O'Brien, P
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Synthesis and characterization of CdS quantum dots in
polystyrene microbeads
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5
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, Fatima, K
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, Nadeem, M
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, Siddiq, M
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(2016)
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 Proceedings of the Royal Society A: Mathematical,
Physical and Engineering Sciences, 472(2186), 20150692
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Carrasco, V
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, Lagos-Moraga, S
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P
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, Faccio, R
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M
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Production of
cadmium sulfide quantum dots by the lithobiontic Antarctic strain Pedobacter
sp
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 Microbial
Cell Factories, 20(1), 1-10
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Majumdar, S
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, Villani, M
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, Pagano, L
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&
White, J
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(2019)
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 NanoImpact, 14, 100151
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Omar, N
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S
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W
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, Anas, N
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A
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S
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, &
Mahdi, M
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(2018)
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Results in Physics, 11, 734-739
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Celebi, S
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K
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, Kurt, A
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Y
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Synthesis and characterization of poly (acrylic acid) stabilized cadmium
sulfide quantum dots
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10
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(2014)
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