Advanced Materials Research Vol. 938

Abstract: AgNPs were synthesized by two different methods chemically using sodium citrate as reducing agent, plant mediated by achyranthes aspera as reducing agent. Chitosan (CS) biopolymer is used as a capping agent in order to enhance the stability and dispersibility as well as to remove aggregation. The appearance of surface Plasmon band in the ultraviolet-visible spectra (410-445 nm) is due to the formation of AgNPs in different sizes. Also the data was clarified that the CS molecules coordinate to the surface of nanoAg particles through their head-groups. FTIR spectra were recorded in a Perkin Elmer version 10.03.06, Spectro Photometer. The FTIR analysis suggests that the prepared chitosan silver nanocomposite film consists of an intermediate/or complex of tri-ammonium citrate, chitosan and metal ions. Finally Antibacterial activity of Ag-CS composites indicating that highest antibacterial activity was detected with green film than chemical film.

Abstract: Layered LiNi_1-xCo_xO₂ is one of the promising cathode materials for Li-ion battery application. However, the Ni rich cathode materials exhibit low capacity and bad capacity retention. This is due to factors such as disorder and structural instability when Li is removed during charge-discharge. Overlithiation of cathode materials is expected to improve the cation ordering and structural stability. Good cation ordering will increase the battery capacity. During charge-discharge, the irreversible Li⁺ loss can be replaced to a certain extent by the interstitial Li⁺ ions in the lattice of the Li_xNi_0.8Co_0.2O₂ material. This helps reduce capacity fading of the cathode materials. In this work the overlithiation of LiNi_0.8Co_0.2O₂ is done by interstitially doping Li⁺ in the LiNi_0.8Co_0.2O₂ materials producing Li_1.05Ni_0.8Co_0.2O₂ and Li_1.1Ni_0.8Co_0.2O₂. Results showthat the performance of the overlithiated LiNi_0.8Co_0.2O₂ materials is better than pure LiNi_0.8Co_0.2O₂.

Abstract: Dyes are a source of serious pollutants from different industrial outlets and show a major contribution in polluting the environment. In the present study two dyes namely Orange G and Acid Blue 113 were compared for their photodegradation efficiency employing rare earth nanometal oxide as a visible active photocatalyst. The prepared catalyst was nanocrystalline form with particle size 70 nm and the surface of the catalyst was highly porous and rough which facilitates the absorption of the dye further enhance the photo degradation which were confirmed by various characterization techniques. Effect of pH, variation of catalyst dosage, variation of initial dye concentration and kinetic studies were conducted for both the dyes. The reaction followed a pseudo first order kinetics. The activity of the prepared catalyst was higher when compared to a commercially used metal oxide. Reusability studies proved that the catalyst prepared was very active even upto the third cycle. The degradation process was initiated by the attack of the OH radical generated in the in-situ process via visible light irradiation. EPR spin trapping technique was employed to confirm the presence of OH radicals. The prepared catalyst degraded the dye molecules of interest in lesser time duration by absorption of visible light, thereby reducing the cost of photodegradation.

Abstract: A hydrogen peroxide sensor was developed by constructing a conductive film of poly (celestine blue) (PCB) on multiwalled carbon nanotubes (MWCNTs) modified graphite electrode by electropolymerization. The presence of MWCNTs increased the surface coverage concentration of PCB and the rate of electron transfer. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the modified electrode. The electrochemical characteristics of PCB/MWCNTs modified electrode was evaluated by cyclic voltammetry and chronoamperometry. The results revealed that the modified electrode exhibits higher electrocatalytic activity towards the reduction of hydrogen peroxide (H₂O₂) in 0.1M of NH₄NO₃ (pH 7) at a reduced overpotential with increased peak currents. The modified electrode showed a wide concentration range from 6.66×10^-6 M to 1.34×10^-3M with a detection limit of 2.22×10^-6 M (S/N = 3) and with a sensitivity of 12.592 μA/μM.

Abstract: Alternative coatings should be as effective as conventional paints but with lower toxicity. In the present study, a commercially available epoxy resin modified with non functionalized nanozinc oxide (nZnO) was examined to get information on its antifouling and anti-corrosive properties. Epoxy nanohybrid coating was synthesized using nZnO (in the amount of 0wt%, 1wt%, 3wt%, 5wt%, 7wt% and 10wt%) and diglycidyl ether of bisphenol A (DGEBA) type of epoxy resin. The curing behavior of these materials was ascertained from FT-IR spectral studies. The anti-corrosive properties of the nanohybrid were investigated using salt spray and electro chemical polarization studies. The surface morphology images were taken by SEM analysis. This study indicates that nZnO particles were dispersed homogenously through the polymer matrix. The nZnO incorporated coating was found to exhibit enhanced anticorrosive performance. Approximately 50% reduction in fouling attachment was achieved with coatings containing 3wt% of nZnO.

Abstract: Composite polymer electrolytes based on poly (vinilydene fluoride-co-hexafluoro propylene) as polymer host, zinc triflate as dopant salt and ZrO₂ as nanofiller were prepared by solution casting technique using N,N dimethylformamide (DMF) as solvent. The loading of the ZrO₂ nanofiller carried out for the optimized composition shows an increasing trend of electrical conductivity from 10^-11 to 10^-5 Scm^-1 at 298 K. The effective structural complexation of the polymer electrolyte system and influence of nanofiller were also analyzed by means of Fourier transform infrared spectral analysis. The detailed impacts on the degree of crystallinity were investigated by differential scanning calorimetric analysis. The electrochemical stability of the optimized composition with 7 wt% ZrO₂ loading was found to exist up to 2.6 V.

Abstract: Efficient light management in solar cells can be achieved by incorporating plasmonic nanoscatterers that support surface plasmons: excitations of conduction electrons at the interface/surface. As known, light trapping increases the amount of light absorbed by bouncing the light within the cell, giving it a chance to be absorbed thereby increasing the absorption and scattering cross-section. The challenge is to fabricate these plasmonic nanoparticles in cost-effective method as well as without hampering optical, electrical and topographical properties of underneath layers. Here in this report a simple two step method was adopted to fabricate silver nanoparticles on zinc oxide followed by topographic and elemental analysis thereof. Numerical calculation was carried out to elucidate optical scattering of silver nanoparticles of various sizes as well as that of dimer. Near-electric field distribution of single silver nanoparticles and dimer along with the individual component of electric field was simulated by finite different time domain analysis. Using the benefit of increased scattering cross-section and ease of such nanoparticles fabrication, a cell configure is proposed herewith.

Abstract: Influence of aqueous cerium oxide nanofluid on the major physicochemical properties of diesel and the performance and exhaust emission characteristics of diesel engine were investigated. 50cc of aqueous cerium oxide nanofluid was dispersed into 1 litre of diesel fuel for preparing test fuel. The diesel with and without aqueous cerium oxide nanofluid was tested in a direct injection diesel engine at 0%, 25%, 50%, 75%, and 100% of full load condition. nanosized cerium oxide has more surface area, higher activity and can react with water at high temperature to generate hydrogen and improve fuel combustion. Also cerium oxide acts as oxygen buffer causing simultaneous oxidation of hydrocarbons as well as the reduction of oxides of nitrogen. The results on the combustion of diesel mixed with aqueous Cerium oxide nanofluid showed an increase in total heat of combustion and a decrease in concentration of HC, NO_x and smoke in the exhaust emission from the diesel engine.

Abstract: Novel nanogold doped TiO₂ nanoparticles are found to be highly efficient for the photocatalytic degradation of organic pollutants. TiO₂ nanoparticles were synthesized from titanium (IV) isopropoxide through hydrothermal route. Gold nanoparticles were prepared by chemical reduction and stabilization employing D-glucosamine, and were doped in TiO₂ nanoparticles. The analysis revealed that the diameter of gold nanoparticles used for doping is around 5 nm. Undoped and gold doped samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis diffuse reflectance spectra (DRS) and field emission scanning electron microscopy (SEM). DRS study showed that nanogold doping in titania nanoparticles induces a shift of absorption edge to the visible range and reduces the band gap. Complementing our earlier finding that noble metal doping in titania nanoparticles enable photocatalytic activity in the visible region, it is showed that gold doping enhances photocatalytic activity of the titania nanoparticles. This was confirmed by the degradation of the dye methylene blue repeatedly using gold doped nanoparticles under direct sunlight. Further, the nanoparticles were used to study the degradation of the persistent organic pollutant, β endosulfan, and near complete degradation were observed in an hour. Regenerated nanoparticles were found effective for the degradation of the pesticide for more than three cycles.

Abstract: Keeping pace with emerging technologies, artificial pancreas is highly recommended to be used as an alternate way to solve blood glucose level problem for Type 1 diabetes patients. It is aimed to develop an embedded nanochip controller in order to regulate the blood glucose level within the safety range. However, due to the lack of effectiveness in algorithm, the blood glucose level in patients body is still not achieving the optimum level. The function of the algorithm, which is the heart of the device, needs to be analyzed in order to ensure the device can be fully utilized. Therefore, system identification technique is applied with objective to study the interrelation among all parameters and variables in the modified diabetic model. As a consequence, the results derived from the method, give us better comprehension in determining which parameters give higher effects on the glucose and insulin system. Thereupon, the main factors in the system are able to be recognized through system identification technique. In this study, parameter t_{max_I} gave highest effect percentage with 66.89% at interaction with insulin,I. On the whole, system identification is very useful to see clear picture of interrelation and correlation in glucose and insulin system.