Polyol Technique Research Articles

Synthesis and characterization of nanostructured tetrahedrite and its composite with dielectric inclusions

The nanostructured Cu–Sb–S materials have been synthesized by a low-cost and versatile polyol technique in a triethylene glycol medium at different temperatures (Ts = 473–533 K). The content of tetrahedrite (Cu12Sb4S13), skinnerite (Cu3SbS3), famatinite (Cu3SbS4), and chalcostibite (CuSbS2) phases was quantitatively determined via the Rietveld refinement of X-ray diffraction (XRD) patterns which showed that Cu–Sb–S pellets densified from powders synthesized at 493 K possess the highest content of tetrahedrite (i.e., ∼96.6 vol%) with small amount of skinnerite (i.e., ∼3.4 vol%). The inclusion of dielectric polyvinylpyrrolidone (PVP) up to 2.5 wt.% to tetrahedrite phase induced the alteration of structural (unit cell parameter a and volume Vunit) and microstructural (sizes of coherent scattering domains L, levels of microdeformations lε, microstresses lσ, and density of dislocations dρ) parameters. The change in the microstructure of Cu12Sb4S13-PVP composites caused the decrease of electronic thermal conductivity κe by 3 times. The increase of Seebeck coefficient (S) resulted in a power factor (PF) of (100–180) μV/K at (300–473) K for Cu12Sb4S13-PVP composite. The presented approach proves the effectiveness of the tuning thermoelectric characteristics of tetrahedrite via admixing with dielectric inclusions.

Enhanced Gas Sensing Performance of CuO-ZnO Composite Nanostructures for Low-Concentration NO2 Detection

The detection of nitrogen dioxide (NO2) is essential for safeguarding human health and addressing environmental sustainability. That is why, in the last decades, gas sensors have been developed to detect NO2 to overcome these hazards. This study explores the use of a novel CuO-ZnO composite synthesized through a polyol and sol–gel technique to enhance gas sensing performance. The CuO-ZnO composite offers the advantage of a synergic combination of its properties, leading to improved sensitivity, selectivity, and low detection limit. The innovative polyol technique employed in this research enables the controlled synthesis of hierarchical CuO and porous ZnO structures. The composite formation is achieved using the sol–gel method, resulting in CuO-ZnO composites with different ratios. The structural, morphological, and optical properties of the materials have been characterized using FESEM, X-ray diffraction, and UV-vis spectroscopy. Gas sensing experiments demonstrate enhanced performance, particularly in sensitivity and selectivity for NO2, even at low concentrations. The composites also exhibit improved baseline stability compared to pristine CuO and ZnO. This study explains the influence of humidity on gas sensing properties by examining interactions between water molecules and sensor surfaces. Notably, the developed CuO-ZnO composite displays excellent selectivity towards NO2, attributed to favorable bonding characteristics and acid-base properties. Overall, this research contributes to advancing gas sensor technology, providing a promising potential for sensitive and selective NO2 detection, thereby addressing critical needs for human health and environmental protection.

A Study of Synthesis and Characterization Techniques for Iron Oxide (FeO) Nanoparticles

Nanoparticles, especially iron oxide nanoparticles, are pivotal in various applications due to their magnetic properties. This research focuses on the synthesis and characterization of iron oxide (FeO) nanoparticles. The study delves into the versatile applications of these nanoparticles, ranging from magnetic colloids to bio-functional uses, highlighting their significance in magnetic bio-separation, magnetic resonance imaging (MRI), and precision drug delivery. The experimental design employs diverse synthesis techniques, emphasizing the gel-evaporation, co-precipitation, reverse micelles, and hydrothermal methods. These approaches offer control over the size and shape of nanoparticles, crucial for tailoring their physicochemical properties. Detailed exploration of the polyol technique and micro-emulsion method provides insights into their mechanisms and the resulting nanoparticles' characteristics. The synthesis of nanoparticles through hydro-thermal conditions is also investigated, elucidating the influence of reaction parameters on particle size and morphology. For comprehensive characterization, various techniques are employed. X-ray Diffraction (XRD) determines crystal structures, while Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) offer morphological and topographical insights. Photoluminescence (PL) is utilized for non-destructive optical characterization, analyzing electron-hole pair generation and recombination. Experimental data is collected using advanced equipment such as the FESEM-Hitachi S4800, JEM 3010 TEM, and a Horiba Jobin Yvon system. XRD scans cover a range of 10 to 75 degrees, SEM provides high-resolution 3D images, TEM allows atomic-level resolution, and PL spectra are acquired for liquid samples.This comprehensive study contributes to the understanding of iron oxide nanoparticles, their synthesis techniques, and their potential applications in various fields. The findings offer valuable insights for researchers and practitioners involved in nanomaterial science, catalysis, and biomedical applications.

Electrocatalysis of ammonia on NiCu nanoclusters with higher activity and stability synthesized by a simplified polyol technique

This work focuses on a simplified polyol process by which to synthesize five different NiCu/C nanoclusters (NCs) electrocatalysts with the variation of mass and atomic ratio. NCs are characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy, transmission electron spectroscopy (TEM), and scanning electron microscopy with energy-dispersive spectroscopy (EDS) for their crystallite and electronic structures, morphological studies, and elemental composition. The high-angle annular dark-field scanning TEM coupled with EDS elemental mapping has confirmed that nanoparticles (NPs) are formed with Ni and Cu, and NPs are subsequently noted to conform into NCs in such a fashion that NiCu NPs are interconnected to each other rather than overlapping considered a unique distribution of NiCu NCs on the carbon support observed in STEM. NPs arrangement in the conformation of NCs has largely increased in the coverage of NiCu-oxyhydroxides working as active sites for ammonia electrocatalysis evidenced in cyclic voltammograms and XPS investigation. NCs were employed for the oxidation of NH4OH, NH4Cl, NH4NO3, and (NH4)2SO4 of which NiCu/C-2 has shown the highest performance over other NiCu/C samples and their individuals. NiCu/C-2 is also found to have higher stability than other mono/bi-metallic electrocatalysts on the stability test preformed in an electrochemical environment. In addition, the sharp drops of the current in the chronoamperometric curves have been investigated during the stability test.

Preparation of anisotropic AgNWs/PVA/Ag2S nanocomposites via a vapor-phase sulfidation process.

This study used a modified polyol technique to synthesize silver nanowires (AgNWs), which were subsequently mixed with polyvinyl alcohol (PVA) polymer and air-dried under ambient conditions. As a result, AgNWs/PVA nanocomposites with a concentration of 2% were prepared by a casting process. After that, the upper surface of the produced samples was treated with H2S gas, as a result of which asymmetric structures were formed depending on the gas concentration, exposure time and penetration into the layers. The structural, morphological, and optical properties of these asymmetric structures were analyzed. Changes in the sample structure were studied using X-ray diffraction (XRD), their optical properties were studied using ultraviolet-visible (UV-Vis), Raman spectroscopy, and their morphology using Transmission electron microscopy (TEM). A simple technique involving H2S gas was used for the sulfidation process of the samples, marking the first exposure of AgNW/PVA nanocomposites to such treatment. Examination of the structural and optical properties of the surfaces revealed clear differences in their physical properties after sulfidation. These obtained results were also supported by TEM images. Finally, the successful production of AgNWs/PVA/Ag2S anisotropic structure was achieved by this method.

PtZn alloy nanoparticles with enhanced activity and stability synthesized by a simplified polyol process for electro-oxidation of ammonia

This work reports the synthesis of bimetallic alloy PtZn nanoparticles (NPs) using one-pot glycerol-assisted polyol technique in the presence of Pt(acac)2 and Zn(acac)2 for the electrocatalysis of ammonia fuels. Three different compositions of PtnZn/C (n = 1, 2, 3) electrocatalysts are synthesized in which Pt-content is varied with a fixed Zn-content. PtZn NPs are characterized by X-ray diffractometry (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) for their crystal structures, elemental compositions, and morphological studies. The high-angle annular dark field-scanning TEM-EDS elemental mapping has confirmed that NPs are alloyed with Pt and Zn elements. The electronic structures of alloy NPs are further analyzed by X-ray photoelectron spectroscopy and found a ligand effect resulting in the downshift of d-band center. The incorporation of Zn in NPs decreases the oxygenated species on Pt surface proven by cyclic voltammetry. PtZn NPs are employed for the electrocatalysis of ammonia fuels, namely NH4OH, NH4Cl, NH4NO3, and (NH4)2SO4, where PtZn/C system has shown better electrocatalytic activity than Pt/C. Stability tests are conducted using chronoamperometry for all electrocatalysts of which PtZn/C electrocatalysts have been observed to have good sustainability in the electrochemical environment compared to Pt/C.

Hydrogen Reconversion from Ammonia through Anion Exchange Membrane Electrolysis

Nitrogen-based compounds, especially ammonia, is a promising alternative for the storage and transport of renewable hydrogen over long distances [1]. Considering ammonia as a hydrogen carrier will require studying the conversion (ammonia to hydrogen) and reconversion steps (hydrogen to ammonia). The reconversion of ammonia can take place through electrolysis under alkaline conditions [2] and needs the development of more efficient catalysts. For this, we started studying the electro-oxidation of ammonia in an anion exchange membrane electrolyser over platinum-based and PGM free electrodes with KOH as electrolyte. We have prepared several catalysts, carbon supported platinum, platinum-iridium, and nickel nanoparticles using the polyol technique. Commercial carbon supported platinum nanoparticles was used as catalyst for the cathodes. Catalyst coated substrates (CCS) were then prepared by spraying a catalytic ink over stainless-steel fiber paper for the anode side. The formulation of the ink requires optimizing parameters such as the type of ionomer (nafion, sustanion) and the ratio of ionomer to carbon. Anodes obtained have been assembled with anion exchange membranes and commercial cathodes for ammonia electro-oxidation in single cell. We have compared the performance of these different membrane electrodes assemblies (MEAs) to commercially available ones integrating nickel-iron-cobalt based anodes. The performance of MEAs was analyzed based on polarization curves, cyclic voltammograms and impedance spectroscopy data. Different testing conditions were investigated by varying the ammonia concentration from 0.1 to 1 M, the temperature from 25 °C to 60°C, and the KOH concentration from 0.1 to 5 M.

Photocatalytic degradation of dyes using synthesized δ-MnO2 nanostructures

Nanostructures of manganese dioxide with unobjectionable properties can be employed to degrade organic waste. The polyol technique was used to create δ-MnO2 nanostructures (NSs), which were then characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Ultraviolet-visible spectroscopy (UV–Vis). The Tauc plot predicted the band gap energy of various molar ratios as 3.02, 2.53, and 2.45 eV. The net charge and stability of δ-MnO2 were pH-dependent, influencing Congo red (CR) and Methylene blue (MB) dyes degradation efficiency. Moreover, various characteristic parameters viz; pH, time, and catalyst dosage on the degradation of dyes were also investigated, and more than 50% CR degradation was observed within 5 min. Photo-degradation study of dyes revealed that MB was degraded effectively at alkaline pH, unlike CR. However, reverse degradation was seen with CR on increasing the dose from 10 mg.

Investigation of Luminescence properties of Bi3+, Dy3+ doped LaAlO3 nanophosphors for radiation dosimetry applications

Bi, Dy co-doped LaAlO3 nanophosphors were synthesized by adopting the Polyol technique to study enhanced photoluminescence. PXRD and Photoluminescence characterizations were done to probe the structure and luminescence studies of the synthesized nanophosphors. It was found that Dy3+ ions has exhibited excellent characteristic emission at 576nm with an increase in photoluminescence during the 4F9/2–6H13/2 transition when compared with single doping and co-doping with Bi3+. The results indicated that the developed (LaAlO3: Bi3+, Dy3+) phosphors under UV radiation could be suitable to be used for radiation dosimetry in cancer applications.

Controllable synthesis of xPt–yNiO/MgO–PWAC nanoparticles and high-efficiency conversion for CO2/CH4 reforming reaction

Utilization and conversion of CO2 through dry reforming of methane to syngas have attracted very great attention because of china's action plans of carbon neutrality to cut net CO2 emissions to peak by 2030. Hence, we designed/prepared a series of high-performance xPt–yNiO/MgO–PWAC (Persimmon Wood-derived Activated Carbon) nanoparticle catalysts via polyol technique. Its catalytic performance and stability were evaluated for CO2/CH4 reforming reaction at 700–800 °C. The experimental results demonstrated that initial conversions of CO2 and CH4 over 1.5Pt11NiO/MgO–PWAC catalysts were 96% and 95.3%, respectively, higher than those observed over 11NiO/MgO–PWAC due to a fact the appreciate Pt loadings will significantly improve the dispersion of Ni/Pt nanoparticles and suppress the formation of coke on the active sites of nickel nanoparticles effectively. The results of HRTEM, TG–DSC XRD, CO2-TPD, and XPS studies revealed that high catalytic performance of catalyst correlated closely with the size and dispersion of metal nanoparticles, the preferred properties of CO2 adsorption as well as low carbon deposition on the interface between active Ni sites/MgO-PWAC supports.

Synthesis of carboxylated-silver nanowires: Electrical conductivity enhancement of isotropic conductive adhesives and long-term stability in a mixture of solvents

Incorporation of silver nanowires in conductive adhesives leads to the reduction of resistivity due to the increased surface area and reduction of contact resistance. However, due to high surface energy, aggregation in the adhesive polymeric matrix leads to performance decline. In this research, in order to solve the aggregation issue and increase the contact surface area, silver nanowires functionalized with carboxylate groups and 21.6 μm and 130.5 nm lengths and diameters were synthesized via polyol technique with a −49.7 mV zeta potential at pH = 7 in aqueous media (energy barrier ≈ 20 KBT). Also, functionalized nanowire suspension was stored in a mixture of solvents containing isopropyl alcohol, 1, 4-dioxane, and dimethyl sulfoxide maintaining stability for more than one year at the room temperature. Due to the good dispersion of the as-prepared silver nanowires in epoxy resin, increased adhesion density, reduction of air entrapment in the adhesive matrix during the curing process, and reduced oxidation rate, the as-prepared conductive adhesive with 50 wt% silver and 5 wt% polyethylene glycol showed a resistivity of 1.895 × 10-7 Ω cm.

Synthesis and Characterizations of PdNi Carbon Supported Nanomaterials: Studies of Electrocatalytic Activity for Oxygen Reduction in Alkaline Medium.

Electrocatalytic materials offer numerous benefits due to their wide range of applications. In this study, a polyol technique was used to synthesize PdNi nanoparticles (NPs) with different percent atomic compositions (Pd = 50 to 90%) to explore their catalytic efficiency. The produced nanoparticles were characterized using X-ray diffraction (XRD) and electrochemical investigations. According to XRD measurements, the synthesized NPs were crystalline in nature, with crystallite sizes of about 2 nm. The electrochemical properties of the synthesized NPs were studied in alkaline solution through a rotating ring-disk electrode (RRDE) technique of cyclic voltammetry. The PdNi nanoparticles supported on carbon (PdNi/C) were used as electrocatalysts and their activity and stability were compared with the homemade Pd/C and Pt/C. In alkaline solution, PdNi/C electrocatalysts showed improved oxygen reduction catalytic activity over benchmark Pd/C and Pt/C electrocatalysts in all composition ratios. Furthermore, stability experiments revealed that PdNi 50:50 is more stable in alkaline solution than pure Pd and other PdNi compositions.

The luminescence characteristics of Pb1-xEuxSe photonic QDs prepared via polymethoxy-ethylhexyloxy-phenylenevinylene assisted polyol technique for laser applications

The photonic crystals based semiconductor quantum dots have revealed auspicious characteristics for the optoelectronic devices. The most difficult way to achieve lasing lies in the creation of sufficient nonradiated Auger recombination’s process. Therefore, there is a real demand to enhance the lasing efficiency, either by increasing the concentration of quantum dots or through the improving of the optical gain or optimizing the optical waveguide. In this article, Pb1-xEuxSe photonic QDs have been prepared via polymethoxyethylhexyloxyphenylenevinylene assisted polyol technique for improving the quantum yield and amplify the photonic gains. The XRD inspects the cubic phase of the Pb1-xEuxSe photonic QDs. The TEM reveals the increasing of the sizes of these QDS from 2.2 nm to 8.1 nm due to the doping of Eu-atoms. The Eu-dopant decreased bandgaps of PbSe nanocrystals from 1.56 eV to 1.32 eV because of the creation of sublevels within the PbSe badgap. The emission spectra revealed the amplification of photonic gains which resulted in the increase of emitted photons intensity by 35 time and the increase of sharpness of the spectral bandwidth by 4 times. The quantum yield improved to 88 %. The amplified optoelectronic gain and high quantum efficiency renders the Pb1-xEuxSe photonic QDs to be used for IR-imaging and optical communications application.

Development of NbxCd1-xTe nanocrystals with high quantum yield using N-methylphenyldiamine assisted polyol technique for IR-diode laser applications

Here we report for the first time, the syntheses of NbxCd1-xTe nanocrystals at diverse contents of niobium dopants using N-methylphenyldiamine assisted polyol technique for IR-diode laser applications. The rule of Nb dopant on the phase, shape and optical behavior of CdTe nanocrystals were evaluated. It was found that the Nb dopant expanded the crystal structure of CdTe without altering the cubic phase. The Nb dopant enlarged the particle sizes of CdTe from 2.5 nm to 11 nm. The Nb-dopant reduced the CdTe bandgap from 2.47 eV to 2.16 eV. The Nb-dopant increased the emission spectra by 10 times and narrowing the spectral bad widths by 4 times. The developed NbxCd1-xTe nanocrystals acquired remarkable quantum yield of 84 %. These marvel features may acquire the developed NbxCd1-xTe nanocrystals for prospective diode lasers, light emitting displays, and optical transistor applications.

The interact of photons of light with photonic gold nanocrystals prepared using eriocephalus punctulatus assisted poly-yol route

Nanophotonics has demonstrated a prodigious potential for quantum optics technology because of their capability to modulate the light photons at the nanoscale. The interaction of light photons with nanophotonic metallic crystals is a crucial clue for the use of these nanophotonic crystals in the applications of ultra-fast data processing, high-density data storage, optical sensors and surface coloring. In this report nanophotonic gold crystals with diverse sizes were prepared via eriocephalus punctulatus assisted polyol technique. The TEM disclosed that nanophotonic gold nanocrystals were formed with spherical shape and the sizes of these crystals changed from 1.9 nm to 5.8 nm. The HRTEM inspected the lattice constant is size independent. The phase of the formed nanophotonic gold crystals is cubic lattice structure as evidenced using X-ray diffraction measurement. The optical absorbance spectral curves showed a resonance absorbance bands in the wavelength ranged from 540 nm–570 nm. These resonance peaks confirmed the surfaces polarization of the nanophotonic gold crystal as a result of light photon interaction. The resonance frequency was found nanophotonic crystal size dependent. A rainbow of color with various wavelengths from 450 nm to 625 nm was emitted under the light impact. The stimulus of light photons on the nanophotonic gold crystals showed an outstanding non-linear optical performance may pave the way to use this sort of nanophotonic crystals as optical sensors, multicolor chromic window and waveguides.

Multicolour tuning of different RE ion doped CaMoO4 nanoparticles by single wavelength excitation

A novel Li+ co-doped RE doped CaMoO4 nanospheres were synthesized adopting polyol technique under urea hydrolysis method. XRD confirms that all the ensued particles are crystallized in the scheelite type tetragonal phase. Transmission electron microscopy observation confirms the formation of small spherical undoped and 5 at % Eu3+, Sm3+ and Dy3+ doped CaMoO4 NPs with a narrow particle size distribution and an average particles diameter of 10.64, 7.18, 3.77 and 3.62 nm, respectively. An increase in the emission intensity with the incorporation of Li ion in the host lattice was discussed in detail. It was found that Li+ ion act as a charge compensator or sensitizer for decreasing emission intensity ratios of MoO42− group to the activator ions. Our work may provide an alternative pathway for tailoring nanocrystals with enhanced optical properties, paving the way for their utilities in the commercialization in optical display systems, lasers and optoelectronic devices.

Development of a new family of spinel nano-ceramic ferrites based on Ni1-xHoxFe2O4 (0 ≤ x ≤ 0.07) via a 1,4-dithioerythritol assisted polyol technique

A new family of nanoferrites composed of Ni1-xHoxFe2O4 (0 ≤ x ≤ 0.07) was developed via a 1,4-dithioerythritol assisted polyol technique. The influence of holmium (Ho) cations on the lattice constant, nanoparticle size, and stoichiometry of the cubic spinel structures were examined using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Doping with Ho cations (up to 3 wt%) in Ni1-xHoxFe2O4 causes an increase of the nanocrystal diameter and the lattice constant. The FTIR and Raman measurements showed the migration of iron cations from tetrahedral to octahedral sublattices due to incorporation of Ho cations. Magnetic (M-H) measurements demonstrated that Ni0.97Ho0.03Fe2O4 exhibits a remarkable improvement of the coercive field (129.7 Gauss) and the saturation magnetization (36.6 emu/g) compared with NiFe2O4, for which the coercive field is 23.3 Gauss and the saturation magnetization is 7.5 emu/g. The enhancement of magnetic constants by more than five orders of magnitude for Ni1-xHoxFe2O4 nano-ceramics make them promising as magnetic catalytic materials and magnetic nanocarriers for drug delivery applications.

Effect of low-density polyethylene on the luminescent properties of thulium-doped yttrium oxide obtained by the polyol technique

In the present work polyethylene is used as a support of yttrium oxide particles doped with thulium atoms and its effect on the luminescent properties is studied. Thulium-doped yttrium oxide was prepared through the polyol method, different values of thulium are explored: 0, 0.5, 1, 1.5, 2.5 and 3.5 at%, as well as different calcinating temperatures: 400, 600, 800 and 1000 °C, are explored in order to determine the synthesis conditions needed for the maximum emission intensity, whose values were 1.5 at% of thulium and 1000 °C. The synthesized powder is dispersed in low-density polyethylene and dispersed as a thin film on glass substrates. The luminescent excitation and emission spectra showed important changes attributed to the influence of the -CH2– chain vibration; in addition, the presence of the polymer had an important influence on the emission decay time: while the powder showed a single emission process with a time of 9.293 μs, the film showed a two decay process with 1.156 μs and 4.086 μs, each.

The charge transport mechanism of a photodiode made of silver sulfide quantum dots decorated graphene for selective detection of blue light

A novel photodiode made of silver sulfide quantum dots decorated graphene was developed for the first time for the selective detection of blue light. The process of the decoration of graphene surface with silver sulfide quantum dots was performed through the synthesis of Ag2S QDs in the presence of graphene solution via polyol technique. The X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and energy dispersive electron diffraction spectroscopy confirmed the successful decoration of graphene surface with Ag2S QDs. The high-resolution transmission electron microscopy revealed that the Ag2S QDs were distributed uniformly on the graphene surface and the average diameter of these QDs was around 8 ± 2 nm. The optical absorption measurements comprises that the decoration of graphene with Ag2S QDs leads to a red shift of the spectrum and an increase of the optical absorption by two times. The luminescence measurements revealed that the decoration of graphene with Ag2S QDs led to a decrease of the luminescence intensity, implying the efficient separations of electrons and holes. The photo-electrical properties indicated that the Ag2S QDs decorated graphene exhibited photodiode like behavior with high response to blue light. The luminescence intensity exhibited a linear regression against the photocurrent up to 5 lx. Therefore, the developed photodiode showed a promising potential to be employed as efficient selective photodiode for blue light.

Light interaction with the copper nanocrystals with various sizes prepared via portulaca oleracea assisted polyol technique

A series of copper nanocrystals with various sizes was prepared by using the extract of portulaca oleracea leaf as an efficient reducing agent and hydrolyzed polyvinyl alcohol as stabilizing agent. The X-ray diffractions disclose cubic structure of these copper nanoparticles. The TEM measurements inspected the monodispersion of the Cu nanoparticles and the increase of their diameters from 2.4 nm to 8.3 nm. The HRTEM inspected the tendency of the Cu nanoparticles to grow along (111) planes. The optical absorption spectra revealed a strong absorption spectrum in the visible region, which argued to the localized surface plasmon resonance. The resonance plasma frequency is exponentialy decreases with the increase of the size of Cu nanoparticles. The luminescence spectrum displaced from 603 nm to 654 nm because of the increasing of Cu size. The scattered wavelengths from the surface of copper nanocrystals exhibited fabulous emitted colors. These unique features may enable the prepared copper nanocrystals with various sizes to be employed for optical remote sensing, optical filters, waveguides and transmitting antenna applications.