Abstract: Zinc Oxide thin films were prepared for different precursor solution molarities from 0.025M to 0.1M by spray pyrolysis deposition technique. A comprehensive study was carried out to realize the effect of concentration of precursor on ZnO thin films. The optimized temperature of the glass substrate was 300°C. From the XRD data it is inferred that the films are polycrystalline and hexagonal wurtzite structure . The degree of preferred orientation were along diffraction planes (100), (002) and (101) for all the ZnO films. The intensity of the diffraction peak prepared with 0.1M concentration is higher than those prepared at lower concentrations. The grain size (D) was calculated using Debye-Scherrer formula. It was found that the average grain size increases, when the molar concentration increases. As the solution concentration increases, the band gap decreases. The films are transparent in the visible region (85%), and the transmittance decreases as the molar concentration increases, which is caused by optical scattering at grain boundaries.
Abstract: The present study reports the enhanced electrocatalytic activity of Ni-Co alloy coatings due to addition of known quantity of carbon nanotube (CNT) into the bath. The Ni-Co-CNT composite coatings were electrodeposited on copper substrate from a sulphate bath, using glycerol as the additive. Electrocatalytic efficiency of the coatings, used as electrodes were tested for both Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER) in 1M KOH using cyclic voltametry and chronopotentiometric techniques. The experimental conditions were optimized to maximize the electrocatalytic activity of both Ni-Co and Ni-Co-CNT coatings for HER and OER. The experimental results revealed that Ni-Co-CNT coatings deposited at high current densities are more favorable for OER and HER, compared to bare Ni-Co coatings deposited from same bath, under same condition. The substantial improvement in the electrocatalytic activity of Ni-Co-CNT composite coatings was attributed to increased porosity due to addition of CNT. The structure-property relationship of both Ni-Co and Ni-Co-CNT alloy coatings for HER and OER were used to explain the role of CNT in enhancing electrocatalytic activity, with the support of XRD, SEM and EDX analyses.
Abstract: The current work involves the measurement of thermo physical properties of commercial available blue dyed Kerosene, examining their behavior with alumina nano particles. It was found that the particle size of alumina ranged from 32 nm – 50 nm from the scanning electron microscope (SEM) analysis. Low volume concentrations (0.01%, 0.05% and 0.10% by volume) were used for this study. The parameters studied were thermal conductivity, viscosity and surface tension. The study was conducted at different range of temperatures (25-60 °C). Oleic acid was added as surfactant and the nanofluid was found to be stable for more than a week. The conductivity of the blue dyed kerosene alumina nanofluid increased with an increase in temperature and volume concentration. An enhancement of 9.33 % in conductivity was observed with a temperature of 60 °C for a volume concentration of 0.10%. The viscosity of the blue dyed kerosene decreased with increase in temperature. An average enhancement of 20% in viscosity of blue dyed kerosene alumina nanoparticles has been noted for a volume concentration of 0.10% as compared to the base kerosene. The surface tension of the kerosene alumina nanofluid decreased with an increase in temperature and decrease in concentration. An enhancement of 7.9 % in surface tension has been noted for volume concentration of 0.1% as compared to base kerosene at same temperature. The effect of temperature on thermo physical properties was determined by a linear decrease in surface tension as the temperature was raised. The results provide a strong proof that the addition of nano particles intensified the thermo physical properties to a considerable rate.
Abstract: Bi2O3 nanostructures were synthesized through a simple electrolysis based oxidation using NaOH electrolyte and annealed at 300 °C, 400 °C, 500 °C and 600 °C. The obtained Bi2O3 nanostructures were characterized using X-ray diffraction and photoluminescence spectroscopy (PL). Bi2O3 crystal structure was confirmed by XRD. When free electron and holes are combined together then emission signals are emitted from PL spectra. With this process, it is studied about the recombination and separation of photo generated holes and electrons. The photocatalytic activities of Bi2O3 films were evaluated for the degradation of Congo red in aqueous solution under UV light irradiation. Among the four samples, Bi2O3 films annealed at 300 °C have better efficiency in removing the congo red dye. For Bi-3, the initial concentration of 10 ppm decreases to 1.11 ppm after 420 min.
Abstract: Aluminium (Al) doped Zinc oxide (ZnO) thin films of different thicknesses were prepared on glass substrates by sol-gel spin coating method. The effect of thicknesses on micro-structural and optical properties was investigated for transparent conducting oxide (TCO) application in solar cells and other optoelectronic applications. Grazing incidence x-ray diffraction (GIXRD) showed maximum orientation along (002) plane of c-axis. The variation of different structural parameters like crystallite size, micro-strain, c-axis strain, dislocation density as a function of film thickness was investigated. The FTIR spectra confirmed the formation of Al-doped ZnO film. FESEM images showed spherical shaped nanosized grains and formation of micro pores. The optical absorption increased and absorption peak shifted towards longer wavelength (red shift) with increase in the thickness of the film respectively. The optical transmittance of all the films has a transparency of more than 75% in the visible region. The optical band gap (Eg) decreased with increase in the film thickness. The diffused reflectance (DRS) showed very low reflectance in the region of 400-800 nm, but increased in the 800-900 nm region. Photoluminescence (PL) spectra of the prepared films showed intense band edge UV and low intense visible emissions respectively. The effect of thickness of Al-doped ZnO film on micro-structure, surface morphology, optical absorption and transmittance, diffused reflectance and PL have been investigated and the results are reported.
Abstract: Biogas is a promising alternative fuel for compression ignition (CI) engines owing to its renewability and carbon neutrality. In this study, biogas was used along with diesel in a CI engine in dual fuel mode, i.e. biogas is inducted along with air and this mixture is ignited by the in-cylinder injection of diesel. The viability of using cerium oxide (CeO2) nanoparticles as an additive to diesel was also explored. The effects of three parameters, viz. biogas flow rate and concentration of CeO2 nanoparticles and applied load on engine performance were investigated under constant speed operation. These parameters were varied in the ranges of 0 - 12 litre/min, 0 - 35 mg/litre and 5 - 22 N.m respectively. The experimental test matrix was reduced to 16 trials using Taguchi’s approach. Performance was quantified in terms of brake thermal efficiency, volumetric efficiency, diesel consumption, exhaust gas temperature and overall equivalence ratio. The criteria for optimum performance were defined as maximum brake thermal and volumetric efficiencies and minimum diesel consumption, exhaust gas temperature and overall equivalence ratio. Optimum operating conditions were identified by evaluating the signal to noise ratio (SNR) for each performance parameter and using the higher-the-better (HTB) or lower-the-better (LTB) condition as applicable. Contributions of individual parameters towards the performance indices were found using ANOVA. Load was found to be the main contributing factor for brake thermal efficiency, exhaust gas temperature and overall equivalence ratio. Biogas flow rate showed significant contribution towards volumetric efficiency. Biogas flow rate and load had comparable influences on diesel consumption. Addition of nanoparticles showed minor contribution towards all the performance parameters.
Abstract: Citric acid assisted auto combustion method was used in the synthesis of BiFeO3 nanoparticles. The synthesized nanoparticles were characterised using X-ray powder diffraction, Scanning electron Microscope, BET surface area analysis, UV-Visible Diffuse Reflectance Spectrometer and Vibratory Sample Magnetometer. The photocatalytic behaviour of the BFO nanoparticles has been studied by the degradation of the direct blue dye. It is observed that BFO shows a good photocatalytic degradation of dye in the visible light irradiation. The effect of pH, catalyst quantity has been studied. The optimum condition is identified as pH 2 and 150mg of the photocatalyst in 10ppm of the dye solution. The magnetic property of BiFeO3at room temperature helps in the efficient removal of them from the treated dye solution. The ability of BiFeO3 nanoparticles to absorb the solar energy and using it for the treatment of water gives it an upper hand over other photo catalysts like Titanium Oxide (TiO2) and Zinc Oxide (ZnO).
Abstract: The polymer blend electrolytes composed of poly (ethyl methacrylate)(PEMA) and Poly (vinyl acetate)(PVAc) as host polymer and lithium perchlorate (LiClO4) as a salt are synthesized by solvent casting technique. The polymer membranes with different wt% of PEMA and PVAc are subjected to AC impedance analysis for the investigation of ionic conductivity. The maximum ionic conductivity of 3.541 X 10- 5Scm- 1 at 303K is reported for PEMA/PVAC (70/30wt%) –LiClO4 (8wt%) polymer blend electrolyte system.The complexation has been confirmed by XRD and FTIR techniques. The glass transition temperature (Tg) of the blend polymer electrolytes has been obtained from DSC measurements. The SEM micrographs show the surface morphology of the prepared samples. The electrochemical stability of the sample exhibiting high conductivity has been carried out using linear sweep voltammetry (LSV) and cyclic voltammetry (CV) measurements. The potential window has been found to be-2.5 to +2.5 V. The lithium transference number evaluated using chronoamperometry technique results in a value of 0.90. The dielectric behavior of the solid polymer blend electrolytes has been analyzed as a function of frequency and temperature. The dc conductivity values obtained from the conductance spectra match the ac impedance results. The photoluminescence spectra that contain information about the local free volume of the prepared samples justify the conductivity results. The two and three dimensional images of the maximum ionic conducting sample exhibit numerous micropores.
Abstract: Copper oxide doped titania nanocatalysts preparation was carried out by combustion synthesis method. The precursor compounds for the preparation of these nanocatalysts were titanium iso propoxide, glycine, copper nitrate and strontium nitrate. The prepared catalysts were characterized by Energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Scanning electron microscopy (SEM), BET Surface area measurement and Infrared spectroscopy (FTIR). Total acidity of the prepared catalysts were determined by temperature programmed desorption of ammonia (TPD-NH3). There was no characteristic peak of copper oxide in the XRD pattern. The photo activity of these prepared catalysts was examined for the degradation of methylene blue dye, which is a common environmental pollutant. These catalysts can be used to degrade the dye from water and thus helps the aquatic life.
Abstract: In this paper, NiO-Gadolinia Doped Ceria (10 mole % Gadolinia) NiO-GDC10 composite with Nickel varying from 50 to 65 wt.% has been prepared by conventional solid state reaction method. The structural and microstructural properties have been evaluated by X-ray diffraction and scanning electron microscopy, respectively. The electrochemical behavior of the composites with varying concentration of Ni has been investigated by AC impedance spectroscopy. Both the grain and grain boundary conductivities have been determined as a function of temperature in the range of 773-973 K. The highest total electrical conductivity (σGi+σGb) have been achieved as 0.28 x10-3 Scm-1 at 973 K with activation energy of 0.40 eV for composition of GDC10 with 65 wt % of NiO (NiO-GDC-65:35 wt.%). The influence of microstructure on electrical properties of the composites has been analyzed and the conductivities have been compared with the conventional NiO-YSZ (50:50) composite in order to fabricate Ni-GDC based anode material of better performance.