Band 112, Heft 12

Highly ordered titania nanotube arrays were synthesised on titanium metal foil through electrochemical anodisation. The annealed samples were characterised through scanning electron microscopy and X-ray diffraction analysis. The electrochemical characterisations of the arrays were done through cyclic voltammetry, galvanostatic charge discharge and electrochemical impedance spectroscopy analyses. The titania nanotube arrays exhibited a specific capacitance of 6.8 mF cm –2 at 5 mV s –1 scan rate, which is very much higher than that reported earlier. Pseudocapacitive metal oxides were deposited on these arrays forming composite supercapacitor electrodes and their supercapacitor properties were compared with same deposited on bare titanium foil substrates. Pseudocapacitive metal oxides deposited on these titania nanotube array substrates exhibited improved supercapacitor performance and stability over the same deposited on titanium foil substrates.

In this work, we investigate the supercapacitive properties of MoS 2 hollow nano-roses with an open cavity at the centre. The synthesized nano MoS 2 delivered specific capacitance of 180 F g –1 at 1 A g –1 , whereas it was around 22 F g –1 for the bulk MoS 2 , which was synthesized in the absence of the micelle. The cycling stability was very high and retained 98% up to 500 cycles, 85% after 3500 cycles and 80% of the initial capacity at 5000 cycles. The enhanced specific capacitance and cycling stability of the nano MoS 2 is probably due to its flower-shaped morphology which consist of thin sheets of MoS 2 and with a hollow cavity which increases the accessible surface area and stability, respectively.

Two new europium complexes, Eu(NTA) 3 (bath) and Eu(NTA) 3 (DPEPO), were synthesized and characterized by elemental analysis, Fourier transform infrared, mass spectrometry, thermogravimetric analysis and photoluminescence spectroscopy. The room-temperature photoluminescence spectra of the Eu 3+ complexes are composed of the typical Eu 3+ red emission, assigned to transitions between the first excited state ( 5 Δ 0 ) and the multiplet ( 7 F 0-4 ). The results demonstrate that the substitution of water molecules by bidentate oxygen or nitrogen ligands in Eu(NTA) 3 (H 2 O) 2 richly enhances the overall quantum yield ( Φ overall = 12% vs. 87%) and life time values ( τ obs = 339 vs. 521 μs).

Surface aligned, uni-directionally grown, hexagonal nanorod bundles and microrod pillared arrays of zinc oxide (ZnO), were synthesized through a simple, homo-epitaxial growth approach. A uniform layer of ZnO seed was initially prepared on cleaned glass substrates by dip coating and calcination. Uni-directionally oriented ZnO micro– nano structures were subsequently developed on the seeded glass substrates through solvothermal methods, by employing equi-molar solutions of zinc nitrate and hexamethylenetetramine. The reaction parameters that control the surface morphologies and crystal orientations were explored. A solution exchange process was also carried out to prepare perpendicularly aligned ZnO nanorod arrays. The structural and functional features of the resultant samples were studied and discussed with the help of X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence spectrophotometry. A plausible structure dependent growth mechanism of the morphologically varied ZnO was also proposed.

Zinc oxide, a well-known inorganic metal oxide, in nanoparticle form exhibits photo-catalysis, antimicrobial behavior and is also employed in energy cells as well as sensor devices. In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using Adathoda beddomei (A. Beddomei) leaf extract as well as Plectranthus barbatus (P. Barbatus) leaf extract. X-ray diffraction studies confirmed the presence of hexagonal wurtzite structure of ZnO NPs having the least particle size ∼ 18–24 nm, with preferential growth along (101) plane. The UV–visible absorbance spectrum of ZnO NPs exhibited the absorbance band in the range 371– 375 nm. Photo luminescence spectra dominated by a strong luminescence peak at ∼384–394 nm followed by low intensity peaks at ∼444–487 nm. Fourier transform infrared spectra confirmed the presence of ZnO NPs as well as the functional groups of plant extracts. Antibacterial properties of synthesized ZnO NPs were evaluated against Gram-negative bacteria– Escherchia coli ( E. coli ) and Gram-positive bacteria– Listeria monocytogenes . Both bio-synthesized ZnO NPs exhibit significant antibacterial activity only against E. coli . The zones of inhibition were found to be 7 mm and 9 mm for A. Beddomei and P. Barbatus respectively. This study demonstrates utilization of A. Beddomei and P. Barbatus leaf extract for the efficient synthesis of ZnO NPs using a biosynthesis method to obtain significant antibacterial activity.

Copper nanoparticle arrays were synthesized by the aqueous phase chemical reduction of Cu 2+ to Cu 0 using glucose as an environmentally benign reducing agent. The UV absorption spectrum exhibited an absorption band at 554 nm revealing the presence of metallic copper nanoparticles. The catalytic properties of the synthesized copper nanoparticle arrays were investigated by reducing 4-nitrophenol (Nip) into 4-aminophenol (Amp) in the presence of NaBH 4 . In comparison to the commercial copper metal powder, copper nanoparticle arrays exhibited highly improved catalytic performance on the reduction of nitrophenol. The current synthesis approach of pure copper nanoparticle arrays does not require rigorous conditions or toxic agents, and hence it is a rapid, efficient, and green approach for the development of active metallic catalysts.

Nanocrystalline semiconducting NiZrO 3 is prepared via a modified combustion process. The X-ray diffraction pattern shows that the so formed nanopowder is single phase and has an orthorhombic structure. The crystalline size of the as-prepared powder determined using the Scherrer formulae is 22 nm. The UV–visible spectrum revealed that nano NiZrO 3 exhibited an intense absorption band in the ultra violet region and the calculated band gap is 4.25 eV, which suggest the material is a wide band gap semiconductor. The material shows good photo luminescence behaviour with intense emission in the blue region. The material is sintered at a temperature of 1220°C in a microwave furnace. Variation of dielectric properties of this material with frequency and temperature are also analyzed. This material shows good optical and dielectric properties which make it an ideal multi-functional material.

Ni 0.5 Cu 0.5 Fe 2 O 4 nanocrystalline spinel ferrite was synthesized through a lactose monohydrate (C 12 H 22 O 11 · H 2 O) mediated chemical preparation technique (post annealed at 600°C for 4 h). Various analytical results obtained after characterization measurements such as X-ray powder diffraction, ultra violet–visible spectroscopy and Fourier transform infrared spectroscopy measurements were discussed. X-ray diffraction pattern analysis confirmed the formation of nanocrystalline face-centered cubic lattice phase of Ni 0.5 Cu 0.5 Fe 2 O 4 with crystallite size ∼ 9 nm. The Tauc plot corresponding to ultra violet–visible reflectance data employing the Kubelka– Munk function provided a direct transition band gap of 4.92 eV. The characteristic tetrahedral and octahedral vibration bands observed in the Fourier transform infrared spectrum further confirmed that Ni 0.5 Cu 0.5 Fe 2 O 4 nanoparticles were crystallized in spinel structure.

Biosynthesis of metal oxide nanoparticles is an emerging eco-friendly approach. Currently, researchers have been developing various nanomaterials with effective antimicrobial properties with less toxicity to humans. Here, nanostructured ceria or cerium oxide nanoparticles of average crystallite size ∼ 5 nm are synthesized by a chemical co-precipitation method using cerium nitrate hexa hydrate and sodium hydroxide as starting materials. The most fascinating bio-material known to man, deoxyribo nucleic acid (DNA) is used as a biological capping agent to get well dispersed nanoparticles. The structural and morphological characterization of prepared samples was conducted using X-ray diffraction, high resolution transmission electron microscopy and Fourier transform infrared spectroscopy. The synthesized cerium oxide nanoparticle showed potential antibacterial activity against both bacteria and fungi under investigation. The results also showed that the synthesized nanoceria can be used to inhibit the growth of several fungi which will be useful for a number of applications in the biomedical field.

Synthesis of a novel, beaded, hydrophobic/hydrophilic balanced and chemically robust chloro SPIRO polymer matrix consisting of styrene and 4-Chloromethyl styrene (VBC) as backbone and 3,9-Divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane as cross-linking units is demonstrated here. The suspension polymerisation technique was preferred to achieve complete monomer to polymer conversion as well as to attain spherical beaded form. Two different cross-linking densities (2 and 4 mol.%) of polymer supports were synthesized and the composition of the functional bearing site VBC was fixed as 3 mol.% for both supports. The integrity of chloro SPIRO polymer formed was verified by Fourier transform infrared spectroscopy and scanning electron microscopy analysis. Chloro SPIRO resin was subjected to Gabriel Phthalimide reaction to form amino SPIRO resin. Chemical integrity of chloro SPIRO resin was tested in different standard solid phase peptide synthetic conditions and swelling capacity was studied using amino SPIRO resin in different polar solvent conditions. The synthetic capacity of novel amino SPIRO polymer matrix was evaluated by synthesising classically challenging acyl carrier protein peptide by Fmoc strategy. The purity of peptide was checked by high performance liquid chromatography and mass by matrix assisted laser desorption.