Nanoscience & Nanotechnology-Asia - Volume 5, Issue 1, 2015

In this study, we report the synthesis of silver nanoparticles from cinnamon bark extract. The physical charactrization of these silver nanoparticles was verified using UV-visible spectroscopy, scanning electron microscopy, and powder X-ray diffraction. Size distribution of nanoparticles was in the range of 30 to 150 nm. The zeta potential was -32 mV, indicating dispersion ability. Superoxide anion radical scavenging assay showed 82% activity for silver nanoparticles derived from cinnamon bark extract.

A mixed precursor containing tetrabutyl titanate and aluminum isopropoxide was used to prepare TiO2-Al2O3 composite photocatalyst through sol-gel method. The influences of n(Ti)/n(Al) on material structure and photocatalytic activity were studied. The results revealed that the materials have crystal structure of anatase TiO2, and the variation of n(Ti)/n(Al) ratio has very little effect on TiO2 crystallite size and surface morphology. The materials are composed of anatase TiO2 and amorphous Al2O3, and have large surface area at high Al2O3 content. The TiO2-Al2O3 at n(Ti)/n(Al) of 12 has average pore size of 22.4 nm, total pore volume of 0.4493 cm3·g-1, and the highest photocatalytic activity. Methyl orange decoloration on the sample is as high as 95.2% after 90 min of irradiation.

We present in this work and for the first time a high level of integration of piezoelectric nano-cantilevers on a silicon substrate (4 inches in diameter). We use lead titanate – zirconate material as piezoelectric material mainly because of its excellent piezoelectric activity at macro scale. However, its integration within a silicon technological process is limited by the difficulty of structuring this material with sub micrometer resolution at the wafer scale. At the nano-scale many questions still remain unanswered. For example: what becomes of the piezoelectric activity? What are the limitations of the integration level process? What are the best electrodes (bottom and top) for piezoelectric film actuation? In this study we have tried to answer some of these fundamental questions. To this end, we have developed a specific patterning method based on deep UV lithography to fabricate nano cantilevers with a high density of integration. The main objective is to obtain sub-micron features by lifting off a 70-nm thick PZT layer while preserving the material’s piezoelectric properties. We show that for the actuation of a very thin film the choice of the bottom and top electrodes has a strong influence. To analyse the piezoelectric activity at nano scale we use the Piezo Force Microscopy, this measurement approach is a good characterization tool for piezoelectric nano devices

Garcinia morella (Gaertn) Desr. is an annual plant widely found in the states of North-East India and the Himalayan foothills. Garcinia morella (Gaertn) Desr. fruit is known for its high phenolic content. In the present research, we explained a novel green method for the synthesis of antimicrobial silver nanoparticles (AgNPs) using the fruit extract of G. morella (Gaertn) Desr., as an effective substitution for conventional trisodium citrate. G. morella (Gaertn) Desr. mediated AgNPs with average particle size of 120 nm was found to be more effective against Bacillus subtilis MTCC 121 with MIC and MBC values 60±20 and 100±20 μg/mL respectively and against Pseudomonas aeruginosa MTCC 4673 with MIC and MBC values 80±20 and 140±20 μg/mL respectively. Citrate mediated AgNPs with average particle size of 143 nm was found to be less effective against B. subtilis MTCC 121 with MIC and MBC values 80±20 and 160±20 μL/mL respectively and against P. aeruginosa MTCC 4673 with MIC and MBC values 120±20 and 200±20 μg/mL respectively as compared to the fruit mediated AgNPs. G. morella (Gaertn) Desr. mediated AgNPs were found to be smaller in size with larger surface area as compared to that of chemically synthesized AgNPs with bigger particle size and lesser surface area and hence were found to be more effective against both gram positive and negative bacterial models. The G. morella (Gaertn) Desr. mediated AgNPs were found stable even up to 168 hr when stored at room temperature. The green method shows its novelty in terms of stability with better antimicrobial activity and also acts as a suitable substitute for sodium citrate mediated method for the synthesis of AgNPs.

Oil spills, particularly from crude oil, cause not only environmental and ecological problems but also high economic loss because of the importance of crude oil in modern industrial society. In this work, a facile and economic method based on magnetic nanoparticles iron oxides was used for the removal of crude oil from water. Various nanostructures and morphologies of iron oxide were successfully prepared by different techniques. Magnetite spinel structure Fe3O4 was prepared by micro-emulsion method. Infra-red spectrum and thermal analyses indicated that the iron oxide particles of Fe3O4 were surrounded and functionalized by organic species. Scanning and transmission electron microscopes images showed that the magnetite structure of iron oxide possesses spherical shape and is in the nano scale 13 nm. Using solvent thermal technique, nano-sheets of hematite structure α -Fe2O3 were prepared with a particle size of 100 nm. The magnetic properties revealed that the nanoparticles having magnetite structure possess super paramagnetic behavior and exhibit relatively high saturation magnetization. The experimental results of oil spills concluded that the nanoparticles of magnetite structure were effective for oil spill removal where 95wt.% of crude oil was removed from the water surface. The mechanism of oil spill removal may be explained though the fact that the small nano size, low density, hydrophobic character and high surface area of Fe3O4 facilitate the penetration process of nanoparticles inside the oil. Finally, the contents of oil spill were simultaneously aggregated and easily removed by an external magnetic field.

A green procedure for the synthesis of ZnO nanoparticles is described using Prunus Cerasus juice which has an important effect on morphology. The synthesized particles were characterized using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM). Powder X-ray Diffraction analysis confirmed that pure ZnO nanoparticles are in a single phase hexagonal structure.

Nano materials electrodes in fuel cell and battery deliver much higher current compared to other electrocatalytic materials. Nano synthesis by electrodeposition technique is very encouraging, considering, achieving nano grain size, right morphology and the required electrocatalytic properties, with simple controlling parameters of current, potential, electrolyte chemistry and using inexpensive equipments. The paper discusses the mechanism of electrodeposition at atomistic level and the effects of various controlling parameters to enhance the rate of nucleation and depress the rate of growth so that electrodeposition produces nano structure. Organic inhibitors help to form nanodeposit. Pulse current electrodeposition is a better technique than normal DC current to encourage more nucleation than growth. The right operating parameters of a particular metal or oxide nano deposit can be found out by a few laboratory experiments viz. Cyclic Voltammetry, Chronoamperometric and Potentiodynamic Polarization. SEM images exhibit nano structures of few alloys and metal oxides synthesized by electrodeposition for high energetic fuel cell electrodes.