Synthesis and characterization of Mn3O4/MnSnO3 nanocomposites for supercapacitor applications

This paper presents the study of surface morphological, optical and microstructural features of zinc oxide (ZnO) nanofilm layered upon p-type Si substrate of <100> orientation by employing conventional RF magnetron sputtering system at different annealing temperatures. The effect of annealing on the nano-film is examined using different characterization techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), FTIR (Fourier Transform Infrared Spectroscopy), UV-vis spectroscopy and Raman spectroscopy. The sharp diffraction peak at (002) orientation is seen by the XRD spectra which signifies a better growth of single crystalline thin film along the z-axis with the hexagonal wurtzite crystal structure. The surface morphological study shows that the grain size of the thin film intensifies from 22.06 nm to 36.77 nm when the annealing temperature is increased whereas there is a decrease in the values of lattice constants (a=b, c), FWHM (full width at half maximum), residual stress, lattice strain and dislocation density by increasing annealing temperature. The enhancement in the grain size makes the thin film appropriate for MEMS device applications including piezoelectric energy harvesters, gas sensors, etc. The optical bandgap of the ZnO thin film is estimated using Kubelka-Munk (KM) approach and it decreases from 3.23 to 3.16 eV for As-deposited, 400 °C, 600 °C and 800 °C respectively which makes the annealed thin film apposite for optoelectronic device applications. The intensity of the Raman peaks strengthens with the annealing temperature. These results prove that the annealing extensively enhances the crystallinity, structural, morphological and optical features of ZnO thin film and hence becomes suitable for nanoelectronic device applications.

Investigation of the effects of ethanolamine, 2-mercaptoethanol and citrate as capping agent and heteroatom source on ethylene glycol oxidation activity of heteroatom-doped reduced graphene oxide nanocomposites decorated with gold nanoparticles

Synthesis and characterization of NiO/Ni3V2O8 nanocomposite for supercapacitor applications

In this paper, we report a facile low-cost synthesis of the chitin and chitosan-based hybrid nanocomposites for supercapacitors. The chitosan and chitin based hybrid composites functional group analysis, structural, optical and morphological properties were characterized using FTIR spectroscopy, Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy (SEM), respectively. Specific capacitance values of hybrid composites were calculated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge analysis. The hybrid composites asymmetric supercapacitor performance was perceived in the range of −0.2 to 1.0 V. The specific capacitance value was achieved at 542.63 F g−1 at current density value of 0.1 A g−1 for CH-GO-ZnO/PANI hybrid composites. The prepared hybrid nanocomposites exhibit good supercapacitive performance and long-term cycle stability. These results demonstrate the potential of the CH-GO-ZnO/PANI hybrid nanocomposites as a high-performance supercapacitors.

英文延伸摘要 SUMMARY In this study, phase formation and optical properties of (Sb1-xSnx)2Se3 (x = 0.0, 0.1, 0.2, 0.3) and Cu2FeSnSe4 (CFTSe) nanocrystals synthesized by various solvothermal processes were explored respectively. On synthesis at 190˚C in teflon-lined stainless steel autoclave, pure Sb2Se3 nanorods formed for 12 h, while pure (Sb1-xSnx)2Se3 nanorods formed for a longer time, 24-36 h, indicating that the Sn dopant increased the activation energy of Sb2Se3. The substitution solubility of Sn in Sb2Se3 was about 6 at%. The Sb2Se3 and (Sb1-xSnx)2Se3 nanorods were 50-150 nm in width and several μm in length. The growth direction of Sb2Se3 and (Sb1-xSnx)2Se3 nanorods was [001]. The bandgaps of (Sb1-xSnx)2Se3 (x = 0.0, 0.1, 0.2, 0.3) were 1.17, 1.21, 1.25, and 1.27 eV, respectively, which increased with the Sn concentration (x). The Sn-doped Sb2Se3 with tunable bandgap may be a promising candidate for photovoltaic applications. Pure and stoichiometric CFTSe nanocrystals were readily acquired for the Cu2Fe1.2Sn0.8Se4 samples using Fe(CH3COO)2 as the Fe source subjected to synthesis in oleylamine at 270˚C for 96 h. Two sharp Raman peaks at 170 and 186 cm-1 for CFTSe nanocrystals were identified. The higher reactivity of the Fe(CH3COO)2 precursor relative to the FeCl2 one enhanced the growth of pure CFTSe nanocrystals, while more Fe concentration in the Cu2FexSn0.8Se4 (x ≧ 1.3) samples led to the formation of CuFeSe2. The direct bandgap of CFTSe nanocrystals is about 1.16 eV. Key word：(Sb1-xSnx)2Se3、Cu2FeSnSe4 nanocrystals、one-pot system、wet chemical synthesis、 autoclave INTRODUCTION Recently, thin-films solar cells like copper indium gallium selenide (CIGS), and cadmium telluride (CdTe) have made impress improvements in device efficiency. However, due to the scarcity of Ga and In, and toxicity of Cd, both of CIGS and CdTe solar cells can’t popularize. Therefore, erth-abundant, non-toxic and low-cost materials should be explored for high-efficiency solar cells. V-VI compounds such as Sb2Se3, and Sb2S3, and the Cu2-II-IV-VI4 quaternary chalcopyrite compounds such as Cu2ZnSnS4 (CZTS), and Cu2ZnSnSe4 (CZTSe) containing non-toxic, abundant elements, and excellent opitical properties have drawn great attention as potential candidates for CIGS for use as the solar cell absorber layer. In order to opitimize the device conversion efficiency, the band gap of an ideal PV absorber layer should be around 1.3 eV for the single-junction cell and 1.0-1.9 eV for the two-junction cell. These requirements can be achieved by tunning the bandgaps of PV materials via adjusting the chemical compositions. Because few studies about the tunable bandgaps of Sb2Se3 and CFTSe were reported. In the present study, the tunable bandgap of Sn-doped Sb2Se3 nanocrystals and Cu2FeSnSe4 alloys were synthesised by one-pot system. MATERIALS AND METHODS For Sn-doped Sb2Se3 nanocrystals, a mixture of SnCl2∙2H2O, SbCl3 was dissolved in deionized water with magnetic stirring, and Se powders was dissolved in hydrazine. The resultant solution was transferred into a Teflon-lined stainless steel autoclave and maintained at 180-190℃ for 24-48 h. For Cu2FeSnSe4 alloys, a mixture of CuCl, Fe(CH3COO)2, SnCl4∙5H2O and Se powders was dissolved in OLA with magnetic stirring, and then heated at 270˚C in N2. The products was centrifuged and then washed with hexane and ethanol to remove the dissoluble by-product, and finally dried at about 50℃. The microstructure of samples was observed using scanning electron microscopy (SEM), and transmission electron microscopy (TEM).The chemical compositions of samples were measured with energy dispersive spectroscopy (EDS). The phases in the samples were analyzed using a X-ray diffractometer (XRD) and Raman spectra. The optical properties of samples were characterized using diffuse reflectance UV-vis spectroscopy in the range of 400-2000 nm. The valence states of the chemical elements in the samples were measured using X-ray photoelectron spectroscopy (XPS). RESULTS AND DISCUSSION Sb2Se3 and (Sb1-xSnx)2Se3 (x = 0.1, 0.2, 0.3) powders with single orthorhombic Sb2Se3 phase (JCPD 00-072-1184) were synthesized with autoclave at 190°C for 24-36 h. The XRD peaks of (Sb1-xSnx)2Se3 samples shift to lower diffraction angles as compared with that of the Sb2Se3 sample. From XPS measurement Sn and Sb in the (Sb1-xSnx)2Se3 samples are in the oxidation state of 2+ and 3+ respectively. The substitution of Sn for Sb in (Sb1-xSnx)2Se3 reduces its lattice constant because the ion radius of Sb3+, 0.076 nm, is smaller than that of Sn2+, 0.093 nm. The chemical compositions of (Sb1-xSnx)2Se3 samples show that the limit substitution soliblity of Sn in Sb2Se3 lattice is about 6 at%. The optical bandgap of Sb2Se3 and (Sb1-xSnx)2Se3 (x = 0.0, 0.1, 0.2, 0.3) nanocrystals are in the range of 1.17-1.27 eV, which are obtained from their reflectance spectra by performing the Kubelka-Munk transformation, showing that the optical bandgaps increase with the Sn concentrations. The Cu2FeSnSe4(CFTSe) samples were synthesized at 270˚C for 84-96 h to obtain pure CFTSe phase which was characterized by the sharp Raman peaks. The Raman spectrum of the sample with Fe(CH3COO)2 precursor synthesized at 270℃ for 96 h shows two sharp peak at 170 and 186 cm-1, both of which shift to lower frequencies as compared with the corresponding ones, 173 and 196 cm-1, of CZTSe. The variation in frequencies of two peaks is due to the change in the force constant of bond.From EDS/TEM analyses, the average chemical compositions of the CFTSe sample were Cu：Fe：Sn：Se = 25.1：13.0：12.4：49.5. CFTSe samples comprised nanoparticles, about 20-50nm in size, and nanosheets, about 50-100 nm in thickness and several hundred nm in size. When the sample with more concentration of Fe(CH3COO)2, Cu2FexSn0.8Se4(x ≧ 1.3), were synthesized at 270℃ for 72-120 h.The CuFeSe2(44-1305) along with the CFTSe phase was formed. The optical bandgap, 1.16 eV, of pure CFTSe was obtained from its reflectance spectra by performing the Kubelka-Munk transformation, which is close to the reported values. CONCLUSION 1. Sb2Se3 and (Sb1-xSnx)2Se3 (x = 0.1, 0.2, 0.3) powders with single orthorhombic Sb2Se3 phase (JCPD 00-072-1184) were synthesized with autoclave at 190°C for 24-36 h respectively. 2. The maximum substitution solubilities of Sn in Sb2Se3 were about 6 at%. 3. The bandgaps of (Sb1-xSnx)2Se3 (x = 0.0, 0.1, 0.2, 0.3) were 1.17, 1.21, 1.25, and 1.27 eV, respectively, which increased with the Sn concentration (x). 4. pure and stoichiometric CFTSe nanocrystals can be obtained when the Cu2Fe1.2Sn0.8Se4 samle using Fe(CH3COO)2 as Fe source is subjected to synthesis at 270℃ for 96 h in OLA 5. The Raman spectrum of the sample shows two sharp peak at 170 and 186 cm-1. 6. The direc bandgap of CFTSe nanocrystals is about 1.16 eV.

Znic oxide nano- and submicro-structures have been synthesized controllably by the polymeric precursor method (Pechini). In this approach, zinc acetate Zn(CH3COO)2.2H2O, citric acid and ethylene glycol were used as the source of Zn2+, the chelating agent and the connecting agent, respectively. The microstructure of the ZnO nano- and submicro-structures was characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM) with the energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR). The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. Different morphologies such as nanoparticles, circular and hexagonal submicro-rods was achieved by changing EG:CA mole ratio. The ZnO nano- and submicro-rods was obtained with EG:CA mole ratio equal to 4:1.The optical property was investigated by the room temperature photoluminescence (PL) spectra. Rod-like and spherical ZnO nanostructures show strong UV emission but hexagonal ZnO submicro-rods show both UV (at &amp;#x2DC; 384 nm) and green emission (at &amp;#x2DC; 510 nm) are observed in the PL spectra.

High performance graphene-poly (o-anisidine) nanocomposite for supercapacitor applications

Synthesis of α-Si3N4 crystallon by a solvothermal method at a low temperature of 180 °C

This study investigates the influence of various organic modifiers that serve as capping agents on the structure, morphology, electronic properties, colloidal stability, and photocatalytic behavior of ZnO nanoparticles synthesized using the sonochemical method. The capping agents used include citric acid (CA), ethylene glycol (ETG), oleic acid (OA), and poly-(vinylpyrrolidone) (PVP). The synthesized ZnO nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray Spectroscopy (EDS), diffuse reflectance ultraviolet-visible spectroscopy (DRUV-vis), dynamic light scattering (DLS), and electrophoresis (EP). XRD analysis confirmed that all samples exhibited a Wurtzite-type hexagonal structure, with crystal sizes ranging from 17 to 22 nm and band gap energies (E g) between 3.16 and 3.25 eV. Notably, samples synthesized with ETG and OA showed additional absorbance in the visible region. Among the samples, ZnO-ETG demonstrated the highest photodegradation efficiency for reactive black-5 azo-dye (RB5), serving as a model reaction. This work highlights the ability to modulate the properties of ZnO nanoparticles, such as crystal size, morphology, hydrodynamic size, surface charge and Urbach energy, through the choice of organic modifiers that serves as stabilizers, impacting their potential applications in photocatalysis.

Silver nanowires were synthesized by solvothermal method through reducing silver nitrate (AgNO3) with ethylene glycol (EG) in the presence of polyvinylpyrrolidone (PVP). In order to prevent the agglomeration of Ag + in the initial Ag seeds formation, sodium chloride (NaCl) was added into the solution to form AgCl colloids. By dissolving AgCl in the late stages, Ag + ions were released into the solution. So the diameters of silver nanowires could be controlled by modifying the PVP concentration. The effect of reaction time, reaction temperature, and for first time purity of EG over the shape of resulted silver nanowires were investigated. The wire, sphere and tree-like nanostructures were formed with changing these parameters. The structural and optical properties of the silver nanostructures were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and UV–visible absorption spectrophotometer. In order to synthesis silver nanowires with smaller diameters and longer lengths, the optimum molar ratio of PVP/AgNO3, reaction time, reaction temperature, and EG purity were found to be 1.5, 2.5 h, 160 °C, and 99.5%, respectively.

Carbon sponge-type nanostructures based on coaxial nitrogen-doped multiwalled carbon nanotubes grown by CVD using benzylamine as precursor

The role of capping agents on the trapping levels structure and luminescent emission of SrMoO4 phosphors

ZnO nanostructures were synthesized by a proteic sol-gel method, using zinc nitrate hexahydrate and gelatin as precursors. Size and shape evolution of ZnO nanostructures were achieved by annealing temperature in the range 250-1000 oC. The crystalline structure, morphology and optical properties of the ZnO nanoparticles were characterized by X-Ray Diffraction (XRD), Raman Spectroscopy (RS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and room temperature Photoluminescence (PL). The result of structural characterization shows the formation of platelets and nanorods in the micro-scale and ZnO nanostructures with high quality hexagonal wurtzite crystal. Sharp peaks in RS after annealing temperature, related to wurtzite structure, were observed corroborating with XRD and TEM measurements. Room temperature PL spectra showed two contribution bands which peaked at ~380 nm, originating from the recombination of free excitons, and ~520 nm corresponding to the impurities and structural defects, like oxygen vacancies and zinc interstitial. The effects of annealing temperature in the structural and optical properties are detailed and the results compared among the experimental techniques. The high quality of the samples obtained by an alternative organic precursor method opens a low-cost route to technological applications of zinc oxide.

Surfactant assisted, one-step synthesis of Fe3O4 nanospheres and further modified Fe3O4/C with excellent lithium storage performance

In this research, cadmium sulfide nanostructures have been prepared by an ultrasound-assisted method in presence of polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as capping agents. The effects of two different capping agents on the structural and optical properties of cadmium sulfide nanostructures have been investigated by X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron microscopy (SEM) and Fourier transform Infrared (FT-IR) spectroscopy. The XRD patterns show the high purity of samples. The mean crystal's sizes have been estimated by Debye-Sherrer equation and results show the mean crystallite size is decreasing with increase capping agent concentrations. UV-Vis spectroscopy results show a shift in the peaks and broadening with the PVA and PVP increasing. The broadening of the absorbance spectrum with increasing in capping agent concentrations is due to the quantum confinement of nanostructures. The band gap of prepared samples has been estimated by Tauc equation and graph and results show that the band gaps of samples are increasing with increase in the capping agent's concentration. The SEM images show the distribution of the uncapped sample is different from capped samples. FT-IR spectroscopy results show by increasing of capping agent concentration the energy between the functional group is changed and some peaks show a slight shift.