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Abstract: This paper reviews proton-conducting polymer electrolytes comprising different polymers, salts, and acids. The ionic conductivity of plasticized polymer electrolytes has been found to increase with the addition of plasticizers due to the dissociation of ion aggregates or undissociated salt/acid present in the electrolytes, i.e., σ (plasticized polymer electrolytes) > σ (unplasticized polymer electrolytes). Proton-conducting nonaqueous nanocomposite plasticized polymer electrolytes containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), polymethylmethacrylate (PMMA), polyethylene oxide (PEO) polymers; different ammonium salts and acids as proton conductors; ethylene carbonate (EC), propylene carbonate (PC), dimethylformamide (DMF), dimethylacetamide (DMA), dimethyl carbonate (DMC), diethyl carbonate (DEC) as plasticizers; fumed silica and alumina as nano-fillers have been discussed in details. Conductivity studies (effect of salt/acid, effect of plasticizers, effect of nano-fillers, and effect of temperature), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA) studies for these electrolytes have been discussed and reported in the paper. Nanocomposite plasticized polymer electrolytes showed high ionic conductivity (in the order of 10-1 to 10-2 S/cm) at room temperature along with good thermal and mechanical stability due to the simultaneous addition of both plasticizers and nano-fillers. These nanocomposite polymer electrolytes are the best candidates for use in various electrochemical devices like solid-state batteries, fuel cells, supercapacitors, sensors, separators, and other electrochromic devices.

In this study, TiO2 nanofibers were prepared with Polyvinylpyrrolidone (PVP) polymer using sol-gel method via electrospinning technique. Owing to the advantages of small fiber diameter, tunable porosity, low cost, large surface to volume ratio, structure control, light-weight, and less energy consumption, electrospun nanofibers are evolving as an adaptable material with a number of applications, in this case for filtration and environmental/virus protection. Different samples of TiO2/PVP nanofibers have been prepared by changing the parameters to achieve the best result. As the polymer concentration was increased from 6 to 8 wt.% of PVP, diameter of the resultant fibers was seen to be increased, implying decrease in the pore-size of the fibers up to 1.4 nm. Surface morphology has been checked via Scanning Electron Microscope (SEM) images. Crystalline nature has been analyzed by X-ray Crystallography. Using the Bruanauer-Emmett-Teller (BET) test, surface area and porosity has been checked for the suitable application. The synthesized TiO2/PVP nanofibers have tremendous practical potentials in filtration and environmental remediation applications.

Ionic conductivity of polymer electrolytes obtained by complexation of trifluoromethanesulfonic acid (HCF3SO3) (triflic acid) with polyethylene oxide (PEO) has been found to increase with the addition of dimethylacetamide (DMA) as plasticizer. The increase in conductivity has been explained to be due to dissociation of ion aggregates with the addition of plasticizer, which has also been supported by FTIR studies. Plasticized polymer electrolytes have high ionic conductivity but not show better mechanical properties. Nano-sized fumed silica (SiO2) is added to improve its mechanical strength alongwith an increase the ionic conductivity of plasticized polymer electrolytes. Maximum ionic conductivity of plasticized nano-composite polymer electrolytes of 8.14 × 10− 3 Scm− 1 at room temperature has been observed for the composition PEO + 8 wt% HCF3SO3 + 50 wt% DMA + 3 wt% SiO2. X-ray diffraction studies of polymer electrolytes suggests that the amorphous content increases with the addition of plasticizer and nano-filler, which is in agreement with the conductivity results. The small change in conductivity over 30–130 °C temperature range suggests that these electrolytes are suitable for their use in device applications like fuel cells, supercapacitors, sensors, separators and other electrochromic devices. DSC/TGA studies show that these nano-composite plasticized polymer electrolytes possess good thermal properties alongwith high conductivity.

Polymethyl methacrylate (PMMA) photonic crystal has been prepared on quartz substrate by the self-assembly vertical deposition technique. YVO4:Eu3+ inverse opal was obtained by annealing PMMA photonic crystal infiltrated with YVO4:Eu3+ nanophosphors at 500°C for 3 h. Scanning electron microscopy confirmed the development of the photonic and inverse opal structures. Photoluminescence study showed that the luminescence characteristics depended on the position of the photonic stop band. It was observed that the photoluminescence intensity of YVO4:Eu3+ inverse opal was enhanced near the photonic stop bandgap edge as compared with the intensity of a YVO4:Eu3+ nanophosphor powder sample.

Nano-composite polymer gel electrolytes were synthesized by using polyethylene oxide (PEO), ammonium tetrafluoroborate (NH4BF4), fumed silica (SiO2), dimethylacetamide (DMA), ethylene carbonate (EC), and propylene carbonate (PC) and characterized by conductivity studies. The effect of donor number of solvent on ionic conductivity of polymer gel electrolytes has been studied. The mechanical strength of the gel electrolytes has been increased with the addition of nano-sized fumed silica along with an enhancement in conductivity. Maximum room temperature ionic conductivity of 2.63 × 10−3 and 2.92 × 10−3 S/cm has been observed for nano-composite gel electrolytes containing 0.1 and 0.5 wt% SiO2 in DMA+1 M NH4BF4+10 wt% PEO, respectively. Nano-composite polymer gel electrolytes having DMA have been found to be thermally and electrically stable over 0 to 90 °C temperature range. Also, the change in conductivity with the passage of time is very small, which may be desirable to make applicable for various smart devices.

Nano-composite polymer electrolytes containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), ammonium tetrafluoroborate (NH4BF4), and nano-size fumed silica (SiO2) have been prepared and characterized by complex impedance spectroscopy. Ionic conductivity of polymer has been found to increase with the addition of NH4BF4, and a maximum conductivity of 3.62 × 10−6 S/cm has been obtained at 30 wt% NH4BF4. The formation of ion aggregates at high concentration of salt has been explained by Bjerrum’s law and mass action considerations. The conductivity of polymer electrolytes has been increased by three orders of magnitude (10−6 to 10−3 S/cm) with the addition of plasticizer, and a maximum conductivity of 1.10 × 10−3 S/cm has been observed at 80 wt% DMA. An increase in conductivity with the addition of nano-size fumed silica is attributed due to the formation of space-charge layers. A maximum conductivity of 7.20 × 10−3 S/cm has been observed for plasticized nano-composite polymer electrolytes at 3 wt% SiO2. X-ray diffraction analysis of polymer electrolyte system was also carried out. A small change in conductivity of nano-composite polymer electrolytes observed over the 30–130 °C temperature range and for a period of 30 days is also desirable for their use in various applications.

Polymer electrolytes based on polyvinyledene fluoride (PVdF) and ammonium fluoride (NH4F) have been prepared and characterized. Films of polyvinyledene fluoride and ammonium fluoride have been prepared by solution casting technique using tetrahydrofuran (THF) as a solvent. Maximum conductivity of 1.17 x 10-7 S/cm at room temperature has been obtained for polymer electrolytes containing 10wt% NH4F. The conductivity of polymer electrolyte has been increased by three orders of magnitude from 10-7 to 10-4 S/cm with the addition of dimethylformamide (DMF) as plasticizer. The increase in conductivity has been explained to be due to the dissociation of undissociated salt/ion aggregates present in the polymer electrolytes with the addition of high dielectric constant plasticizer (DMF). Maximum conductivity of 1.26 x 10-4 S/cm has been observed for plasticized polymer electrolytes. The variation of conductivity with temperature suggests that these polymer electrolytes are thermally stable and small change in conductivity with temperature is suitable for their use in practical applications like solid state batteries, fuel cells, electrochromic devices, supercapacitors etc.

Optical properties of metallo-dielectric (Gold@silica) composites were measured using different characterizing techniques viz. UV-Visible and photoluminescence (PL) spectroscopy. Reflection spectra showed the Bragg reflection peak shifted to longer wavelength and was broadened with the shell growth. The PL spectra showed the presence of visible and infrared bands. While the visible emission is explained by radiative recombination caused by interband transitions, the infrared emission is accounted for by the intraband transitions. Raman spectroscopy of methyl red (MR) indicator dye adsorbed on metallo-dielectric films has shown an enhancement in the Raman signals on incomplete shells. The enhancement is ascribed to the surface roughness and nanogaps making the synthesized metallo-dielectric particles a potential substrate for surface enhanced Raman spectroscopy (SERS). (c) 2014 Elsevier B.V. All rights reserved.

Metallodielectric (gold@silica) composites were prepared by seed and grow method. The dielectric microspheres (core material) of an average size of 400 rim were synthesized by sol gel method and gold nanoparticles (AuNPs) were prepared by reducing the chloroauric solution. Shell growth around silica (SiO2) microspheres was carried out in a multistep layer-by-layer process. The synthesized composites were characterized using techniques such as field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV-Visible (UV-Vis) spectroscopy. FE-SEM and FTIR analyses have confirmed the functionalization of SiO2 surfaces with the amine terminal group along with the gold shell growth. XRD analysis has given an average crystallite size of 12.3 nm for metallodielectric composites. Absorption spectra have demonstrated the dependence of surface plasmon resonance (SPR) peak on the successive shell growth by exhibiting a red shift.

Multilayer colloidal structures of TiO2 coated silica microspheres have been synthesized by using self-assembly vertical deposition technique and optical properties of these structures were also investigated using UV–visible spectroscopy. Morphology, elemental distribution and chemical bonding information is analysed using scanning electron microscopy (SEM), Energy dispersive X-ray Spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) respectively. It is noticed that position of transmission dip is dependent upon the annealing temperature of the samples. The experimental measured normalized stop band width results are in good agreement with theoretical results at packing fraction value of 0.74.

ZnO is widely used as a functional material because it has a wide and direct band gap, large excitons binding energy, and excellent chemical and thermal stability. ZnO is a semiconductor material which is widely used as transparent electrodes in solar cells, chemical and gas sensors and light emitting diodes, due to its unique electrical and optical properties. Zinc oxide (ZnO) thin films were deposited on glass substrate by dip coating technique. The effects of sol aging time on the deposition of ZnO films were studied by using the field emission scanning electron microscopy (FE-SEM) and optical transmission techniques. Thin films of ZnO were prepared on glass substrate and annealed at 300 C, 350 C and 400 C. The increase in sol aging time resulted in a gradual improvement in crystallinity. Effect of sol aging on optical transparency is quite obvious through increased transmission with prolonged sol aging time. Interestingly, 72-168 h sol aging time was found to be optimal to achieve smooth surface morphology, good crystallinity and high optical transmittance which were attributed to an ideal stability of solution. The UV-Vis transmittance spectrum of synthesized sample suggests the optical band gap value of 3.2 eV. Dip coating technique create ZnO films with potential for application as transparent electrodes in optoelectronic devices such as solar cell.

The planar orientation of Nematic Liquid crystal (NLC) molecules on the surface of (111) plane of silica photonic structure has been investigated. Nano voids of silica photonic crystal has been obtained by vertical deposition technique on indium tin oxide-coated substrate. NLC was infiltrated into the channels of voids in the photonic structures. Optical texture studies under with and without electric field were applied to investigate the NLC orientation. It is observed that NLC molecules in the nano voids of silica photonic structure exhibit an excellent planar alignment. This obtained hybrid composite structure on infiltration of NLC will be a promising candidate for electro optic applications.

In present work photonic crystals of different size of silica microspheres have been fabricated. The optical properties of these developed photonic crystals have been studied using UV-visible spectroscopy. UV-visible spectroscopy shows that they have photonic band gap that can be tuned in visible and infrared regime by changing the size of silica microspheres. The photonic band gap structures of these photonic crystals have been calculated using MIT photonic band gap package. It also reveals that with the increase in size of silica microspheres the photonic band gap shifts to lower energy region.

Tunable photonic crystal has been developed by infiltration of nematic liquid crystal (NLC) and different organic liquids in the void of silica microspheres. Optical properties were investigated by ultraviolet–visible (UV–Vis) spectroscopy. It has been observed that the position of photonic band gap (PBG) shifts from 336[Formula: see text]nm to 326[Formula: see text]nm with the increase of applied field from 0[Formula: see text]V to 9[Formula: see text]V and 316[Formula: see text]nm to 324[Formula: see text]nm after the infiltration of the organic liquids. The refractive index of infiltrated liquid crystal (LC) is calculated at different applied electric field. The present results could be suited for implementation of low cost and compact design tunable devices with low power consumption for high density integrated optics.

In the present work, we have prepared functional dye doped TiO2-SiO2 thin films by vertical sedimentation technique. Thin film samples are annealed at different temperature from 50 o C to 850 o C. Morphology and chemical bonding information is analysed using atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) respectively. Optical properties are characterized by using UV-visible spectroscopy. Effect of annealing temperature on the photonic forbidden band gap is also presented. The experimental measured values are compared with theoretical estimated results.

Colloidal multilayer structures of silica microspheres have been developed on the quartz substrates using vertical deposition technique and effect of annealing on optical properties of samples was investigated using UV-Visible spectroscopy. It is noticed that forbidden photonic band gap is a function of annealing temperatures and annealing times. Morphology of particles was characterized using scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). SEM and TEM micrographs illustrate the uniform size distribution of silica microspheres with an average size of 280 nm. (C) 2011 Elsevier B.V. All rights reserved.

Gold nanoparticles (AuNPs) synthesis is demonstrated successfully using fresh young leaves of Artocarpus Lakoocha (A. Lakoocha), fruit pulp of A. Lakoocha and loquat (Eriobotrya Japonica) leaves. We have also compared green synthesis with chemical assisted tri-n-octyl-phosphine (TOP) stabilized gold nanoparticles. Samples were characterized with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and UV-Visible spectroscopy. TEM images have shown that the average size of the particles is 15.06, 36.8 and 25.08 nm for A. Lakoocha fruits, A. Lakoocha leaves and loquat leaves assisted gold nanoparticles, respectively. Hydrogen tetrachloroaurate is reduced and AuNPs are stabilized by phenols, hydroxyls and carboxyls groups such as terpenoids, flavonoids, tannins etc, present in young leaves and fruit extracts. It was observed that green synthesis using botanical extracts is a cost effective and non- toxic way for nanoparticle preparation.

RhodamineB (RB) dye-doped TiO2-SiO2 core-shell composite microspheres were synthesized by a chemical method from the hydrolysis of the titanium tetrachloride (TiCl4). The morphology and chemical bonding information of composite material was investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). TEM and SEM images illustrate that core-shell composite microspheres are spherical in shape and have a nano-range thin coating of TiO2 on the surface of SiO2. The core-shell composite microspheres calcined at 400°C exhibit sharp XRD peaks of anatase and rutile crystalline phases of TiO2. The unit cell parameters were calculated from different peaks. The FTIR spectrum confirms the existence of stretching modes (Si-O-Si and Ti-O-Ti) in the core-shell composite microspheres. The photocatalytic properties were evaluated by the photo degradation of K2Cr2O7 under ultraviolet-visible irradiation for as-synthesized and at an 850°C calcination temperature of the core-shell composite.