Showing papers in "Journal of Materials Science: Materials in Electronics in 2017"

Surfactants assisted solvothermal derived titania nanoparticles: synthesis and simulation

Abstract: Solvothermal method was used to prepare titanium dioxide (TiO2) nanoparticles (NP’s) of various morphologies at 180 °C growth temperature. Acetic acid and oley amine were used as surfactants. The powder of TiO2 was annealed at 550 and 950 °C for 18 and 24 h. The influence of surfactants on the morphology of titania NP’s was investigated using transmission electron microscopy (TEM). The structural, optical, and molecular properties of titania NP’s are investigated by means of X-ray diffraction, UV–visible, Photoluminescence, and Fourier Transform Infrared. The physical properties, surface area and pore volume, of the samples were investigated by Brunauer-Emmett-Teller and Barrett-Joyner-Halenda measurement. The results illustrated type IV adsorption isotherms for all samples, implying the characteristics of mesoporous materials (2–50 nm). Furthermore, the hysteresis loops shifted to higher relative pressure, indicating that the specific surface area increases and the pore size decreases after heat treatment. Micrograph images acquired from TEM portrayed different shapes such as irregular spherical, rounded rectangular, truncated rhombic, and rod-like for titania NP’s when various surfactants were used. Monte-Carlo simulation carried out for pristine and rutile titania NP’s as representative samples explained the growth mechanism of titania NP’s and corroborated the formation of spherical and rod-like structures due to attractive and repulsive interactions among particle respectively.

Solution processable sol–gel derived titania gate dielectric for organic field effect transistors

Abstract: A gate dielectric has key role in thin film transistors. Insulating polymers incorporated with oxide nanoparticles are the ideal candidates for the gate dielectrics due to their solution processability and relatively high dielectric constant. The polyvinyl alcohol cross linked with ammonium dichromate was spun onto fluorine doped tin oxide (FTO) substrates. Titania particles were incorporated into a mixture of ammonium dichromate and polyvinyl alcohol (PVAad) solution and the resultant films were irradiated by ultraviolet irradiation. TiO2 particles were prepared using acetic acid as a surfactant by sol–gel method. Metal–insulator–semiconductor (FTO/(PVAad + TiO2)/Au) structure was fabricated by evaporating Au electrode. The electrical properties of polymer composites layer have been studied with the effect of binding agent, concentration of TiO2 nanoparticles, and the irradiation of UV light. Capacitance–voltage, capacitance–frequency, and current–voltage measurements were performed using two probes measurement setup. The obtained electrical results illustrated that the dielectric constant of prepared films was increased from approximately 2 for PVAad to 7 for PVAad +TiO2 films. These results further corroborated that the capacitance is independent of frequency and the leakage current was less than 2 × 10−12 A. This leakage current is small enough and hence PVAad + TiO2 is an ideal gate dielectric for the fabrication of field effect transistors. The surface morphology of composite films has been studied by means of field emission scanning electron microscopy. The micrograph images illustrated huge variation in the morphologies of the hybrid films after incorporation titania particles into polymer matrix and UV irradiation.

Green synthesis of zinc oxide nanoparticles using arabic gum and photocatalytic degradation of direct blue 129 dye under visible light

Abstract: In this work, zinc oxide (ZnO) nanoparticles were synthesized using arabic gum as a biotemplate source by the sol–gel method and its photocatalytic dye degradation ability from aqueous solution was studied. This method has many advantages such as nontoxic, economic viability, ease to scale up, less time consuming and environmental friendly approach for the synthesis of ZnO nanoparticles without using any organic chemicals. Direct blue 129 (DB129) was used as model dye. The synthesized ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and UV–Visible spectroscopy. The X-ray powder diffraction (XRD) analysis revealed the formation of wurtzite hexagonal phase ZnO with average crystallite size of 10 nm. Photocatalytic dye degradation by ZnO nanoparticles was studied using UV–Vis spectrophotometer. The effects of process parameters like, catalyst dosage, initial dye concentration, and visible light irradiation on dye degradation have been investigated.

Green synthesis of ZnO nanoparticles by using Calotropis procera leaves for the photodegradation of methyl orange

Abstract: A facile, innovative and inexpensive green route has been demonstrated for the formation of ZnO nanoparticles by biogenic method using aqueous leaf extract of Calotropis procera which acts as a reducing and stabilizing agent. The as prepared ZnO nanoparticles were characterized by a host of different techniques such as X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FT-IR). The XRD pattern confesses that ZnO nanoparticles associate to hexagonal wurtzite structure. The DRS absorption spectrum shows an absorption edge at 397 nm corresponds to the ground excitonic peak of ZnO nanoparticles and the band gap is found to be 3.1 eV. The FT-IR spectra indicate the presence of hydroxyl groups, aldehydes, amines, ketones, and carboxylic acids which are responsible for biochemical reaction. TEM images shows that the particles of ZnO have spherical shape with size ranging from 15 to 25 nm. ZnO nanoparticles were subjected to photocatalytic application for the degradation of methyl orange under UV light. The photodegradation efficiency of MO was found to be 81% within 100 min under UV light, such an excellent activity is obtained by biogenic ZnO NPs.

Optical properties of pure and doped PVA:PEO based solid polymer blend electrolytes: two methods for band gap study

Abstract: In this work an innovative experimental method has been proposed to estimate the optical bandgap and determine the types of electronic transitions. Solid polymer blend electrolyte films based on PVA:PEO have been prepared by the well known solution cast technique. It was observed that the absorption increased with increasing aluminum salt concentration and shifted to higher wavelengths. Shifting of absorption edge to lower photon energy indicates a good reactivity between the polymer blends and the aluminum salt which in turn the energy band gap decrement is expected. An increase in refractive index for the doped samples has been observed. The miscibility between the aluminum salt and the polymer blends can be well understood from the linear relationship between the refractive index and the volume fraction of the added salt. The increase of extinction coefficient at high wavelengths was observed. The optical band gap measured from the plots of (αhυ)^x versus photon energy (hυ) was compared to that determined from the optical dielectric loss. From the results of the present work it is understood that in order to avoid the plotting of many figures based on Tauc model, optical dielectric loss must be studied. Further research works are required to satisfy that the optical dielectric loss can be used to estimate the band gap and identify the types of electronic transition. The Urbach energy was found to increase with increasing aluminum salt concentration.

In situ polymerization of modified graphene/polyimide composite with improved mechanical and thermal properties

Abstract: The graphene oxide was modified by coupling agent (KH-550). The polyimide/graphene treated by KH-550 (PI/KG) composite were prepared by in situ polymerization from 4,4′-diaminodiphenyl ether (ODA), 2,2-bis(4- (3,4-dicarboxyphenoxy) phenyl) propane dianhydride (BPADA), and modified graphene. The structure and morphology of the composite membranes were analyzed by Fourier transform infrared spectroscopy (FT-IR) and X ray diffraction. Compared to pure PI system, the tensile strength and elongation at break of PI/KG-4 composite, increasing by 26.4 and 24.1 %, was 134 MPa and 9.8 %, respectively. The 5 % mass loss temperature of polyimide system was about 486.1 °C, and the PI/KG-6 composite was 493.8 °C. PI/KG composites have a better thermal stability and a higher thermal conductivity compared to PI system with the increasing of KG content.

Cobalt carbonate and cobalt oxide nanoparticles synthesis, characterization and supercapacitive evaluation

Abstract: Taguchi robust design methodology was used to optimize direct precipitation reaction conditions for simple and fast synthesis of cobalt carbonate nanoparticles. The effects of several parameters that influence on particle size of prepared cobalt carbonate were investigated. The significance of these parameters on the size of cobalt carbonate particles were quantitatively evaluated by using of analysis of variance (ANOVA). The results showed that flow rate and the concentrations of cobalt and carbonate solutions have significant effect on the size of cobalt carbonate nanoparticles. Also, optimum conditions for synthesis of cobalt carbonate nanoparticles via precipitation reaction were achieved. The ANOVA demonstrated that under optimum condition, cobalt carbonate nanoparticles will have of 39.6 ± 2.2 nm sizes. In addition, the solid state thermal decomposition reaction of precursor was used for preparation of Co3O4 nanoparticles. The results showed that the Co3O4 nanoparticles synthesized by thermal decomposition of cobalt carbonate nanoparticles have 53 nm sizes. Cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy were used to investigate the supercapacitive property of the Co3O4 electrode. The Co3O4 electrode shows high specific capacitance of 396 F g−1 at scan rate of 2 mV s−1 in 2.0 M H2SO4 electrolyte. Thus, the prepared electrode could be used for supercapacitor.

Gamma-ray shielding properties of zinc oxide soda lime silica glasses

Abstract: In the present work, the gamma ray shielding properties of zinc oxide soda lime silica, (ZnO)x(SLS)1−x glasses with 0 ≥ x ≥ 50 wt% have been investigated. By using WinXCom computer software, the mass attenuation coefficient (µ/ρ) and half value layer (HVL) for total photon interaction in the energy range of 1 keV–100 GeV were calculated. Furthermore and by Geometric Progression method exposure buildup factor values were calculated for incident photon energy 0.015–15 MeV up to penetration depths of 40 mfp (mean free path). The addition of zinc oxide (ZnO) into soda lime silica (SLS) glass resulted in an increase the mass attenuation coefficient and decreases both the half value layer and exposure buildup factor. The obtained results of the selected glass series have been compared, in terms of mass attenuation coefficient, half value layer and exposure buildup factor with some common shielding materials. The shielding effectiveness of the selected glasses is found comparable to that of common ones; which indicates that the SLS glasses with suitable ZnO content may be developed as gamma ray shielding materials.

Evaluation of supercapacitive behavior of samarium tungstate nanoparticles synthesized via sonochemical method

Abstract: The work focuses on the synthesis of Sm2(WO4)3 nanoparticles through a reagent-free aqueous-phase sonochemical reaction between samarium nitrate hexahydrate and Na2WO4.2H2O solutions. The prepared Sm2(WO4)3 nano-structures were also characterized by XRD, EDS and SEM to evaluate their structures and morphology. The magnetic properties of as-prepared Sm2(WO4)3 nanoparticles were also investigated with vibrating sample magnetometer (VSM). Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) have been used to investigate the supercapacitive property of the samarium(III) tungstate electrode. The samarium(III) tungstate electrode shows high specific capacitance of 326 F g−1 at scan rate of 2 mV s−1 in 2.0 M H2SO4 electrolyte. Thus, the prepared electrode could be potential electrode materials for supercapacitors.

The piezoelectric response of electrospun PVDF nanofibers with graphene oxide, graphene, and halloysite nanofillers: a comparative study

Abstract: Although, many efforts were performed to develop piezoelectric systems with high energy conversion rate, but they still show insufficient performance. In this study, the effect of three nanofillers with different morphology and their concentration on macro/micro structure and piezoelectric properties of polyvinylidene fluoride (PVDF) nanofibers were investigated and compared. Graphene oxide (GO) and graphene (Gr) as planner nanofillers, and halloysite (Hal) nanotube were introduced into a PVDF solution in different concentrations (0.05–3.2 wt/wt%). The prepared solutions were fabricated into nanofibers through electrospinning method. The electroactive phase (β-phase) of nanofibrous PVDF mat increased up to ~49% in comparison with PVDF powder. The presence of nanofiller in PVDF matrix also increased it more up to 10%. Gr nanofiller had least effect on piezoelectric properties attributed to its low interaction with PVDF chains. PVDF/Hal nanocomposite with low filler content concentration ( 0.4 wt/wt%) caused higher polar phase. Hal nanotubes with a rod like morphology caused more oriented and finer nanofibers than PVDF/GO and PVDF/Gr nanofibers. However, PVDF/0.8 Hal showed higher output voltage (0.1 V), despite of its lower β-phase in compared with PVDF/0.8GO nanocomposites. It was concluded that the piezoelectric response cannot be just evaluated with dielectric constant of nanofiller or β-phase percentage in an electrospun PVDF nanocomposite, but there are some other important factors like orientation and fineness of electrospun nanofibers.

Green synthesis of ZnO nanoparticles using Carica papaya leaf extracts for photocatalytic and photovoltaic applications

Abstract: We report a facile synthesis of hexagonal wurtzite ZnO nanoparticles through green synthesis method using Carica papaya leaf extract. To understand the structural phase purity, morphology and size, the sample was characterized through various analytical techniques. The obtained results reveal that the synthesized ZnO nanoparticle is a phase pure hexagonal wurtzite structure in spherical shape with particle size of ~50 nm. Furthermore, the synthesized ZnO nanoparticles were used as photocatalyst as well as photo anode for methylene blue dye degradation and dye sensitized solar cells, respectively. It was found that the synthesized ZnO nanoparticles completely degrade the methylene blue dye within 180 min under UV light irradiation. In addition, it shows an energy conversion efficiency of 1.6% with a current density of 8.1 mA cm−2 in dye sensitized solar cells.

The effect of pH on the photocatalytic degradation of methyl orange using decorated ZnO nanoparticles with SnO2 nanoparticles

Abstract: In this study we investigate for the first time the effect of pH on the photocatalytic activity of SnO2 nanoparticles, ZnO nanoparticles and hybrids containing decorated ZnO nanoparticles with difference amount of SnO2 nanoparticles (ZnO–SnO2 (1–0.5) and ZnO–SnO2 (1–2)). The experimental results show that the removal efficiency of methyl orange increases with respect to the irradiation time in all of the tested suspensions. Meanwhile, the effect of pH confirm that the removal efficiency of pollutant in the suspension with natural pH (pH = 7) is higher than that of acidic (pH = 4) and alkaline condition (pH = 10). The results of statistical analysis reveal that the irradiation time and pH have significant impact on the photocatalytic activity of all nanoparticles and hybrids. The coefficient of determination of all proposed models justify that the proposed models can be successfully predicted the removal efficiency of methyl orange in the all suspensions. The results of Duncan’s multiple range test (α = 0.05) demonstrate that there is a significant difference between different levels of pH. Also, the photocatalytic activity of hybrid increase by increasing the decorated SnO2 nanoparticles content.

The effects of (graphene doped-PVA) interlayer on the determinative electrical parameters of the Au/n-Si (MS) structures at room temperature

Abstract: Au/n-Si(MS) and Au/(0.07graphene-PVA)/n-Si(MPS) structures were fabricated on the same wafer at identical conditions and their electrical characteristics have been investigated by using current–voltage (I–V) and capacitance/conductance–voltage(C/G–V) measurements at room temperature. The rectifying rate(RR at ±5 V), barrier height(Φ Bo ) and surface states(N ss ) (at 0.5 eV) for MS structure were found from the I–V measurements as 1.96 × 103, 0.757 eV and 9.67 × 1014 eV−1 cm−2 for MS whereas those for MPS structure were 9.67 × 105, 0.790 eV and 1.04 × 1013 eV−1 cm−2, respectively. The reverse current mechanisms were also discussed by considering Poole–Frenkel and Schottky emissions. The values of RR and N ss of MPS structure are 493.37 times higher and 92.98 times lower than these values of MS structure. The values of doping atoms (N D ), Fermi energy (E F ) and BH were extracted from the reverse bias C −2 –V characteristics at 1 MHz as 2.42 × 1015 cm−3, 0.260 and 0.994 eV for the MS and 0.856 × 1015 cm−3, 0.234 and 0.828 eV for the MPS structures, respectively. These results show that the use of (graphene-PVA) interlayer improves the performance of MS structure and so it may be good alternative to replace the conventional SiO2 due to reduce the number of oxygen vacancies and yields low density of N ss , and increase the BH.

Ammonia gas sensor based on flexible polyaniline films for rapid detection of spoilage in protein-rich foods

Abstract: This work details the fabrication and performance of a sensor for ammonia gas, based on conducting polymer. The fabrication procedure consists following steps; polyaniline synthesis via oxidative polymerization technique, then a sensitive polyaniline film was deposited on a printed circuit board and finally, polyaniline microdevice were assembled on an interdigitated electrode arrays to fabricate the sensor for amomonia gas detection. Response time of this chemiresistive devices and humidity impact were examined for NH3 sensitivity and compared with commercial gas sensors (Taguchi Model 826). Data export from sensor to the computer was carried out via data logger model ADC-24 and analyzed using SPSS software. The sensor was found to have a rapid (t = 40 s) and stable linear response to ammonia gas in the concentration range of interest (50–150 ppm) under room temperature operation condition. It was reviled also reliable results to the variation of environment humidity. Power consumption, sensitivity, dimension, flexibility and fabrication cost were used as most important parameters to compare the new polymer based device with those of other similar works and the results showed that small size, low cost, flexibility, low power consumption and high sensitivity are from the benefits of this innovative device. In real-time application conditions flexible polyaniline based gas sensor with polyimide substrate in thickness 0.25 mm exhibits relatively good performance and accurate evaluation of food spoilage.

Newly developed biodegradable polymer nanocomposites of cellulose acetate and Al2O3 nanoparticles with enhanced dielectric performance for embedded passive applications

Abstract: In this study, biopolymer nanocomposites of cellulose acetate (CA) and Al2O3 nanoparticles (Al2O3 NPs) were successfully obtained using solution blending method. The effect of Al2O3 NPs loading on the microstructure, morphology, thermal and dielectric properties of CA/Al2O3 nanocomposites was investigated using FTIR, XRD, TGA, optical microscopy, SEM, AFM and impedance spectroscopy technique. The FTIR results infer good interaction between CA and Al2O3 NPs. The XRD and microscopic studies demonstrated that Al2O3 nanoparticles were homogeneously dispersed in the CA matrix. The TGA results indicate that the onset degradation temperature of CA/Al2O3 nanocomposites is shifted towards higher temperature in the presence of Al2O3 NPs. The contact angle measurements infer reduction in the wettability of CA matrix with increasing Al2O3 NPs loading. On the other hand, the dielectric properties of CA were improved due to an incorporation of Al2O3 NPs. The dielectric constant increases from 8.63 (50 Hz, 30 °C) for neat CA matrix to 27.57 (50 Hz, 30 °C) for CA/Al2O3 nanocomposites with 25 wt% Al2O3 loading. Similarly, the dielectric loss also increases from 0.26 (50 Hz, 30 °C) for neat CA matrix to 0.64 (50 Hz, 30 °C) for CA/Al2O3 nanocomposites with 25 wt% Al2O3 NPs loading. However, very low values of tan δ (below 1) were observed for all the samples. These results suggest that CA/Al2O3 nanocomposites with improved dielectric properties seem to be a promising candidate for designing electronic devices such as embedded passives.

New and highly efficient Ag doped ZnO visible nano photocatalyst for removing of methylene blue

Abstract: Due to excellent properties, recently ZnO nanomaterials are used as very efficient photocatalysts for the photocatalytic degradation of toxic organic dyes and chemicals under various light radiations. In this article we used a new and simple method for synthesis of high efficient AgxZn1−xO (x = 0, 0.3, 0.5, 1, 2, 4, 6) nano photocatalyst in visible region. The process is simple, cost-effective and can be easily scaled-up. It was shown that the catalytic behavior of ZnO that is synthesized with this method has good efficiency about 63% for degradation of methylene blue in visible-light illumination.With doping of a little (0.5%) Ag the photocatalytic activity in the visible-light range is notably improved with a maximum effeciency of 98% degradation of methylene blue. In this work Ag doped and oxygen vacancy defects on the surface of ZnO nanoparticles benefit the separation of photogenerated electron–hole pairs, thus lead to enhancing the photocatalytic activity. The properties of the nanoparticles were characterized by the employments of UV–Vis spectroscopy (UV–Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR),photoluminescence (PL), field emission scanning electron microscopy (FESEM) and scanning energy dispersive X-ray spectroscopy (EDS).

Photocatalytic and antibacterial activities of hydrothermally prepared CdO nanoparticles

Abstract: CdO nanoparticles (NPs) were synthesized (hydrothermal) with cadmium acetate and ammonium hydroxide as starting materials and characterized by XRD, FE-SEM and FTIR. It exhibits face centred cubic structure with an average crystallite size of 43 nm and the lattice strain (W–H plot) is 0.0029. The surface morphological image appears particle like structure (150 nm). The vibrational stretching mode of Cd–O is 620 cm−1 whereas micro Raman reveals the overtone at 389 cm−1. The optical energy bandgap is found to be 2.47 eV from the UV–Vis spectra. Five emission peaks were recorded at 360, 429, 488, 527 and 640 nm upon excited at 290 nm. The SHG efficiency is 0.84 times of KDP. The photocatalytic performance has been evaluated of the CdO NPs for the degradation of methylene blue under sunlight irradiation. CdO NPs were screened for their in vitro antibacterial activity against human pathogens such as Gram negative (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris) and Gram positive (Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis) bacteria has been investigated.

In situ synthesis and preparation of TiO2/polyimide composite containing phenolphthalein functional group

Abstract: In this paper, titanium dioxide (TiO2)/phenolphthalein-type polyimide (PPPI) composite was synthesized in situ polymerization, the diamino phenolphthalein type compound and dimethylacetamide as the matrix, and TiO2 as the filler. The mechanical property and thermal conductivity properties were used to characterize the properties of the obtained composite. A diamine monomer containing more benzene rings of phenolphthalein and an ether bond in its main chain were prepared, synthesized by a nucleophilic substitution reaction and a hydrazine hydrate reduction reaction. Polyimide composite had the same structure as that of a diamine monomer. And it was synthesized by solution imidization and heat imidization. The results showed that TiO2 improved the dispersibility, alignment and interfacial strength of the TiO2/PPPI composite. The mechanical property of polyimide composite was increased with the increasing TiO2 loading. And a suitable addition of TiO2 could enhance the mechanical properties of polyimide system. Compared to polyimide resin, the TiO2/PPPI composite had a higher thermal conductivity with the increasing of TiO2 content. All of these changes in properties were closely correlated with the TiO2/PPPI composite, which could form an interaction interface structure in the system.

Photocatalytic degradation of methylene blue by hydrothermally synthesized CZTS nanoparticles

Abstract: Due to the toxic effect of Methylene blue (MB) dye, its removal from water and water waste has gained significant attention in concern with green environment. In present work, a simple and low cost hydrothermal method has been used for the synthesis of copper zinc tin sulfide (CZTS) nanoparticles. Structural, morphological and optical properties of CZTS nanoparticles were characterized and it reveals that the synthesized powder has kesterite crystal structure with agglomerated morphology and shows a band gap of 1.53 eV leading to good potential to degrade methylene blue dye. When CZTS was introduced in aqueous MB solution as a catalyst and exposed to visible light for 45 min, about 50% degradation of MB was observed.

Cu–Sn and Ni–Sn transient liquid phase bonding for die-attach technology applications in high-temperature power electronics packaging

Abstract: Power electronics modules in electric vehicles and hybrid electric vehicles, particularly those containing next-generation power semiconductor devices such as silicon carbide and gallium nitride are operated at high temperatures exceeding 200 °C. Consequently, the reliability requirements for such modules have become highly stringent and new packaging materials and technologies are required to meet the demands of power electronic modules. Some good candidates for high temperature applications include high-temperature solders such as Au–20Sn, Ag or Cu sinter pastes, and transient liquid phase (TLP) bonding materials. In particular, the TLP bonding technology is suitable for use in high temperature environments owing to its low cost and simplicity of the bonding process. In this study, the feasibility of Cu–Sn and Ni–Sn TLP bonding technologies as die-attach methods for power electronics packaging applications is examined. The results of the study indicate that the Cu–Sn and Ni–Sn TLP bonding processes transform the joints fully into Cu6Sn5/Cu3Sn and Ni3Sn4 intermetallic compounds (IMCs), respectively. Further, the mechanical strength and reliability of the two TLP bonding joints are reduced owing to the formation of brittle IMCs.

Nanocomposite of ZIF-67 metal–organic framework with reduced graphene oxide nanosheets for high-performance supercapacitor applications

Abstract: Demand for new energy storage devices stimulates efforts to develop the novel and effective composites with promising properties. For this purpose, composite materials, including carbonaceous materials such as graphene, carbon nanotube and carbon fiber and metal containing compounds have attracted an increasing attention because of better electrochemical performance as compared to their single material analogs. Here, the Nanocomposite consisting of ZIF-67 nanocrystals on reduced graphene oxide nanosheets (rGO/ZIF-67) has been prepared via a simple and facile ultrasonic route at room temperature. Electrochemical properties of the rGO/ZIF-67 and ZIF-67 were measured by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy techniques in 6 M KOH as an electrolyte. The nanocomposite of rGO/ZIF-67 showed highest specific capacitance value of 210 F/g at a current density of 1 A/g which is much higher than that of ZIF-67 at a similar current density (103.6 F/g). EIS measurements exhibited lower values of internal resistance and charge transfer resistance for the composite electrode in comparison to ZIF-67 electrode, indicating that the prepared nanocomposite has higher electrical conductivity. The prepared nanocomposite showed excellent cycling performance (80% after 1000 successive cycles at a current density of 1 A/g), indicating that the ZIF-67 nanocrystals immobilized on the surface of rGO nanosheets are beneficial to improving electrochemical properties as compared to ZIF-67 single analogs and is an appropriate candidate for supercapacitor applications.

Green synthesis and characterization of NaEuTi 2 O 6 nanoparticles and its photocatalyst application

Abstract: In the current study, an attempt is made to synthesize NaEuTi2O6 nanoparticles via a green route with the aid of sodium nitrate, europium nitrate, and tetra-n-butyl titanate in an aqueous solution environment. Besides, the effect of several carbohydrates such as glucose, galactose, lactose and starch on the morphology and particles size of products was investigated. In addition, decolonization of methyl orange azo dye was performed in order to investigate NaEuTi2O6 nanoparticles photocatalysis application. The nanoparticles structure has been elucidated by X-ray diffraction analysis, scanning electron microscope, X-ray energy dispersive spectroscopy, and vibrating sample magnetometer. Photocatalysis results reveal that maximum degradation (90%) was occurred under UV light irradiation. DRS used to study the optical properties of NaEuTi2O6 nanoparticles.

Striking multiple synergies in novel three-phase fluoropolymer nanocomposites by combining titanium dioxide and graphene oxide as hybrid fillers

Abstract: In this study, novel three-phase polymer nanocomposites comprising of polyvinylidene fluoride (PVDF), titanium dioxide (TiO2) nanoparticles and graphene oxide (GO) were prepared using colloidal blending. The PVDF/TiO2/GO nanocomposites were characterized by FTIR, XRD, TGA, optical microscopy, SEM, AFM and contact angle analysis. The dielectric properties of these three-phase polymer nanocomposites were investigated using broadband dielectric spectroscopy in the frequency range 50 Hz–20 MHz and temperature in the range 40–150 °C. The FTIR and XRD results infer good interaction between the constituents of nanocomposites. The microscopic studies infer homogeneous dispersion and distribution of TiO2 nanoparticles and GO within the PVDF matrix. A notable improvement in the thermal stability of PVDF was observed by the addition of TiO2 and GO as hybrid fillers. The dielectric performance of PVDF/TiO2/GO nanocomposite films was significantly improved as compared to PVDF/TiO2 (90/10) nanocomposite film. The dielectric constant increases from 18.57 (50 Hz, 150 °C) for PVDF/TiO2 (90/10) nanocomposite film to 165.16 (50 Hz, 150 °C) for PVDF/TiO2/GO nanocomposite film containing 7 wt% TiO2 and 3 wt% GO loading. In addition, the dielectric loss also increases from 1.71 (50 Hz, 150 °C) for PVDF/TiO2 (90/10) nanocomposite film to 3.68 (50 Hz, 150 °C) for PVDF/TiO2/GO nanocomposite film containing 7 wt% TiO2 and 3 wt% GO loading. These intriguing properties of PVDF/TiO2/GO nanocomposites could shed some light on the incorporation of different types of hybrid fillers in a suitable polymer matrix for the development of novel three-phase nanocomposites as intelligent materials for embedded passive applications.

Water-promoted zeolitic imidazolate framework-67 transformation to Ni–Co layered double hydroxide hollow microsphere for supercapacitor electrode material

Abstract: Hollow Ni–Co layered double hydroxide (LDH) was synthesized with rhombic dodecahedral zeolitic imidazolate framework-67 (ZIF-67) as self-sacrificed template and cobalt precursor. Water was found to be very important role on the formation of Ni–Co LDH hollow microstructure. As a supercapacitor electrode material, the obtained hollow Ni–Co LDH delivered a high specific capacitance of 1530 F g−1 at the current density of 1.0 A g−1 and good cycle performance, which can be ascribed to its hollow mesoporous structure composed of the Ni–Co LDH nanosheets and high specific surface area. Combined with the AC negative electrodes, the assembled asymmetric supercapacitors performed an energy density of 27.5 Wh kg−1 at the power density of 375 W kg−1.

Schiff-base hydrothermal synthesis and characterization of Nd2O3 nanostructures for effective photocatalytic degradation of eriochrome black T dye as water contaminant

Abstract: Nd(OH)3 nanostructures have been prepared through a new simple hydrothermal approach with Nd(NO3)3·6H2O and tetraethylenepentamine (tepa) as starting materials in presence of bis-(2-hydroxynaphthaldehyde)-1,2-phenylenediamine as novel capping agent. Bis-(2-hydroxynaphthaldehyde)-1,2-phenylenediamine was employed as capping agent in presence of tepa to produce nanostructured Nd(OH)3 for the first time. Pure hexagonal Nd2O3 nanostructures with superior photocatalytic activity were synthesized by thermal conversion of nanostructured Nd(OH)3 in air at 700 °C for 4 h. The formation of as-obtained nanostructures and their structure and shape were analyzed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). By varying the precipitator type, reaction time and applying Schiff base ligand as novel capping agent, the approach permits us to produce samples with various particle sizes and shapes. In addition, the photocatalytic performance of as-produced Nd2O3 samples with various particle sizes and shapes was investigated by degradation of eriochrome black T dye as water contaminant.

Polyvinyl alcohol (PVA)/polystyrene sulfonic acid (PSSA)/carbon black nanocomposite for flexible energy storage device applications

Abstract: Herein, we report the preparation and characterizations of polyvinyl alcohol (PVA) and polystyrene sulfonic acid (PSSA) blend nanocomposites reinforced with carbon black nanoparticles (CBNPs). The structural changes, interaction between CBNPs and the PVA/PSSA blend matrix were identified by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies. The surface morphology of PVA/PSSA/CBNP nanocomposite films were evaluated using polarized optical microscopy (POM) and scanning electron microscopy (SEM) and the mechanical properties were evaluated using bench top tester. In addition, the dielectric properties of PVA/PSSA/CBNP nanocomposite films with different loadings of CBNPs were carried out in the frequency range 50 Hz to 20 MHz at various temperatures ranging from 40 to 150 °C. The dielectric constant as high as 1851 (50 Hz, 150 °C) was obtained for the PVA/PSSA/CBNP nanocomposite film with 5 wt% CBNPs loading and for the same compositions the dielectric loss was about 3.9 (50 Hz, 150 °C. The dielectric results demonstrate that the dispersion of CBNPs has a significant control on the percolation threshold of nanocomposites. The enhanced dielectric performance of these nanocomposites infers that CBNPs are ideal nanofillers for the development of novel high-k materials with low percolation threshold for flexible energy storage applications.

Solid state thermal decomposition synthesis of CuO nanoparticles from coordinated pyrazolopyridine as novel precursors

Abstract: The complexes derived from reaction of copper(II) salts (Cl−, Br−, CH3COO− and SO 4 −2 ) 2-(3-Amino-4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-1-yl)acetohydrazide were prepared and characterized. Different standardized instruments were used for obtaining the required data (spectral method UV–Vis., IR, 1H-NMR, mass spectra) magnetic susceptibility and thermogravimetric analysis TGA were performed. The electronic spectral data and magnetic moment values proved that all the copper complexes have octahedral geometry. CuO nanoparticles with 15.5 nm of particle size have been synthesized via solid state thermal decomposition using these copper (II) complexes as new precursors. Surface morphology of the synthesized CuO nanoaprticles were investigated by Ultraviolet visible light spectroscopy (UV–Vis), X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The photocatalytic activity of CuO nanoparticles was assessed toward photocatalytic degradation of MB dye and the results exhibited 97 % efficiency with degradation rate of 0.018 min−1.

Influence of capping agents additives on morphology of CeVO4 nanoparticles and study of their photocatalytic properties

Abstract: In this paper, cerium vanadate (CeVO4) nanoparticles were synthesized via a precipitation method on the reaction between cerium nitrate hexahydrate and ammonium metavanadate in water. Besides, three capping agents such as glucose, lactose and starch were used to investigate their effects on the morphology and particle size of CeVO4 nanoparticles. According to the vibrating sample magnetometer, cerium vanadate (CeVO4) nanoparticles indicated a paramagnetic behavior at room temperature. To evaluate the catalytic properties of nanocrystalline cerium vanadate, the photocatalytic degradations of methyl orange under ultraviolet light irradiation were carried out. The structural, morphological, magnetic, and optical properties of as-obtained products were characterized by techniques such as XRD, SEM, EDX, VSM, and UV–Vis spectroscopy.

Improvement of composition of CdTe thin films during heat treatment in the presence of CdCl2

Abstract: CdCl2 treatment is a crucial step in development of CdS/CdTe solar cells. Although this processing step has been used over a period of three decades, full understanding is not yet achieved. This paper reports the experimental evidence for improvement of composition of CdTe layers during CdCl2 treatment. This investigation makes use of four selected analytical techniques; Photo-electro-chemical (PEC) cell, X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM). CdTe layers used were electroplated using three Cd precursors; CdSO4, Cd(NO3)2 and CdCl2. Results show the improvement of stoichiometry of CdTe layers during CdCl2 treatment through chemical reaction between Cd from CdCl2 and elemental Te that usually precipitate during CdTe growth, due to its natural behaviour. XRD and SEM results show that the low-temperature (~85 °C) electroplated CdTe layers consist of ~(20–60) nm size crystallites, but after CdCl2 treatment, the layers show drastic recrystallisation with grains becoming a few microns in size. These CdCl2 treated layers are then comparable to high temperature grown CdTe layers by the size of grains.

Facile synthesis and characterization of CdTiO 3 nanoparticles by Pechini sol–gel method

Abstract: In this work, CdTiO3 nanoparticles were synthesized through reaction between Cd(CH3COO)2.2H2O, Ti(OC4H9)4, trimesic acid as a new chelating agent and ethanol as solvent by Pechini sol–gel method. X-ray diffraction (XRD) patterns showed that CdTiO3 nanostructures have rhombohedral structure with diameter of about 35.61 nm. The structure, morphology and size of CdTiO3 nanoparticles were characterized by FT-IR, XRD, SEM and EDAX. The optical properties of the products were studied by DRS. Based on the results of experiments, it was found that temperature and time of calcination, pH and the solvent of reaction are important parameters for formation of CdTiO3 nanoparticles. Utilizing trimesic acid (benzene-1,3,5-tricarboxylic acid) as a new chelating agent for preparation of CdTiO3 nanostructures was initiative of this work.