Influence of chelating agents on structural, optical, and electromgnetic interference properties of copper selenide nanoparticles synthesized via microwave-assisted method
Recently, group II-VI binary semiconductor nanomaterials including copper selenide (CuSe), have garnered increased attention due to their remarkable properties that differ significantly from their bulk counterparts, as their functions are highly dependent on particle size, shape, and surface prop...
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104236/1/FS%202022%2021%20IR.pdf |
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| Summary: | Recently, group II-VI binary semiconductor nanomaterials including copper selenide
(CuSe), have garnered increased attention due to their remarkable properties that differ
significantly from their bulk counterparts, as their functions are highly dependent on
particle size, shape, and surface properties. To tune the overall properties of this
nanoparticle, various surface modifications are required, such as capping the surface with
organic, inorganic, and polymer-based chelating agents which can be used in various
applications. In this work, CuSe nanoparticles were synthesized using a simple, low-cost,
and environmentally friendly microwave method. Optimization of synthesis conditions
such as microwave power, irradiation time, hydrazine hydrate concentration, and copper
concentration was carried out to obtain a pure single-phase CuSe nanoparticle. Singlephase
CuSe nanoparticles were obtained at 380 W microwave power, 20 minutes of
irradiation time, 3 ml of hydrazine hydride, and 0.9:1 copper to selenium molar ratio.
The effect of chelating agent concentrations on the structural, morphological, and optical
properties of CuSe nanoparticles was fully investigated. Six different chelating agents
were used: tartaric acid (TA), ethylenediaminetetraacetic acid (EDTA), citric acid (CA),
cetyl ammonium bromide (CTAB), polyvinylpyrrolidone (PVP), and polyethylene
glycol (PEG).
X-Ray Diffraction (XRD) analysis revealed that all samples formed a pure single-phase
hexagonal (Klockmannite) crystal structure. The XRD analysis result is in agreement
with the energy dispersive X-ray (EDX) and Raman analysis. At various concentrations
of TA, EDTA, CA, CTAB, PVP, and PEG, the average crystallite size estimated using
Scherer’s method decreased from 73.10 to 16.10 nm, 73.10 to 16.80 nm, 73.10 to 18.20
nm, 73.10 to 43.60 nm, 73.10 to 14.00 nm, and 73.10 to 21.20 nm respectively. The
Williamson-Hall method revealed an estimated crystallite size that is comparable to
Scherer's method. The atomic force microscopy (AFM) and field emission scanning
electron microscopy (FESEM) analysis agree with the obtained XRD results. At various concentrations of TA, EDTA, CA, CTAB, PVP, and PEG, the optical band gap increased
from 1.80 to 2.10 eV, 1.80 to 2.20 eV, 1.80 to 2.25 eV, 1.80 to 2.30 eV, and 1.80 to 2.24
eV, respectively. This is attributed to the decrease in particle size of the final product.
Besides, photoluminescence (PL) maximum emission for all the samples was centered
at 610 nm. The PL intensity was found to increase with increasing chelating agent
concentrations in all samples.
Other than that, the effect of particle size of CuSe NPs as nanofiller loaded in the PVA
polymer matrix on dielectric properties and electromagnetic interference shielding
effectiveness (EMI SE) was investigated. The result showed that the dielectric constant,
loss factor and loss tangent increases with the decrease in CuSe nanofiller size. This is
because smaller particles fill the matrix evenly, forming a chain-like network in the PVA
matrix. Moreover, the EMI SE measurement results showed that reflection loss (SER),
absorption loss (SEA), and total interference shielding (SET) decreases with an increase
in frequency, which is attributed to the impedance mismatch of the EM waves as the
applied frequency is increased from 8 to 12 GHz. Additionally, the nanocomposites
exhibited a high absorption potential for electromagnetic waves (SEA), but a significant
portion of the EM wave was also reflected (SER). The contribution of SER and SEA to
SET increased as the size of the CuSe nanofiller is decreased. The nanocomposites
showed the SET is higher than the target value of 20 dB. Thus, the results show that
incorporating CuSe NPs of various sizes into a PVA polymer matrix significantly
improves the total shielding effectiveness of EM waves, implying that the prepared
nanocomposites can be used as lightweight, flexible, and low-cost material for
electromagnetic interference shielding applications. |
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