Journal of Advances in Nanomaterials

11

Authors: Lee D. Cremar, Ben Jones, Nicole Martinez, Gustavo Mejia, Hilario Cortez, Edgar Muñoz, Rocío Nava, Karen Lozano

Nitrogen doped carbon fibers were synthesized from polyvinyl alcohol (PVA), a water soluble precursor. The PVA fine fibers were first developed by centrifugally spinning an aqueous based solution using Forcespinning® technology. The precursor fibers were then exposed to sulfuric acid vapors to partially carbonize and stabilize the fibers for further heat treatment. For nitrogen doping, the fibers were exposed to two different heat treatment routes. One was under a nitrogen atmosphere at 850°C followed by exposure to ammonia gas at 500°C. The second route consisted of heating the treated fibers in pure ammonia gas only, up to 850°C. Both heating schemes resulted in carbon based fibers that showed evidence of nitrogen content as shown by energy-dispersive X-ray spectroscopy. The second route showed an effective doping of the carbon fiber with nitrogen atoms, measured by X-ray photoelectron spectroscopy, which indicated that the nitrogen atoms were fully incorporated into the carbon framework.

12

Authors: Tayseir M. Abd Ellateif, Saikat Mitra

Hydrophobic mesoporous zirconia containing silica nanoparticles was synthesized via sol gel process. Silica sol was prepared and subsequently liquid modified with different proportions of zirconia. The effects of zirconia content on the silica textures and properties were studied. TGA results confirmed the development of hydrophobicity in zirconia containing silica nanoparticles. The synthesized nanoparticles were characterized by FTIR and XRF. The topography of silica particles changed as a function of zirconia content as evident from FESEM and TEM results. From XRD investigation, surface area measurement and pore size analysis it was observed that the synthesized silica was semi amorphous materials with very narrow pore diameter distribution as a function of zirconia content. From nitrogen physisorption studies mesoporous nature (type V) of the synthesized silica was noted. The synthesized pure silica possessed significant surface area while the zirconium content caused a reduction on the surface area of silica zirconium nanoparticles.

7

Authors: Yongkui Huang, Zhiyuan Yang, Shuijin Yang, Yulin Xu

H3PW12O40/SiO2 was prepared by a sol-gel method, and sensitized by H2O2 solution. Their photocatalytic effects on degradation of organic dyes were investigated under simulated natural light irradiation. Degradation of methyl orange was used as a probe reaction to explore the influencing factors of the photodegradation reaction. After used continuously for five times, the catalytic activity of the photocatalyst is not any lower. The photodegradation of methyl orange, methyl red, methyl violet, rhodamine B, malachite green and methylene blue were also tested, and the degradation rate of dyes can reach 84.6 %~98.3 %. It was found that the photodegradation reaction belongs to the first-order kinetic reaction.

9

Authors: Praveen Kumar Singh, Soumya Mukherjee, Chandan Kumar Ghosh, Saikat Maitra

TiO2 nanoparticles were synthesized by sol-gel method from titanium tetra isopropoxide. Influence of heat treatment on structural and morphological properties of TiO2 nanoparticles was investigated by XRD and SEM. Spectral properties of the nanoparticles were investigated using FTIR, Raman spectroscopy, PL spectroscopy and UV–visible absorption spectroscopy. XRD analysis revealed the formation of mixed anatase and ruitle phase in the synthesized powder at 550oC and existence of only rutile phase at 750 and 900oC. The lattice parameters, crystallite sizes, volume of the unit cell, density and surface area of TiO2 nanoparticles were determined from XRD analysis. SEM analysis showed that the prepared nanoparticles were in the nano regime, nearly spherical and larger agglomerated at lower temperature. EDX analysis showed that the TiO2 composition obtained was near stoichiometric at lower temperature and the proportion of oxygen vacancy increased with the increase in temperature. The presence of Ti-O and Ti-O-Ti bonds was confirmed by FTIR spectra. PL spectroscopy showed that the change in surface states and presence of anatase and rutile phases of TiO2 were also responsible for exhibiting the change in PL intensity. UV–visible absorption spectra showed the shifting of absorption edge towards the higher wavelength with the increase in temperature while the corresponding energy band gap of semiconductor nanoparticles decreased. Change in Raman spectra with the increase in temperature was observed due to anatase to rutile phase transformation and with the increase in the particle size.

13

Authors: Nidhi Shah, Karan Bhangaonkar, Dipak V. Pinjari, Shashank T. Mhaske

CeO2/ZnO composite nanoparticles are synthesized by using in-situ precipitation method, without any stabilizers, via conventional i.e. non-ultrasound (NUS) and ultrasound-assisted processing technique (US). The structure, morphology, particle size and % weight loss of the synthesized nanoparticles were analyzed by using X-ray powder diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) to establish the formation of core shell type nanomaterials with an average particle size under 15 nm. The effectiveness of the synthesized core shell morphology of CeO2/ZnO (catalyst) for the photocatalytic degradation of Rhodamine B (RhB) dye has also been investigated. It has been observed that the catalysts prepared by sonochemical method exhibit higher photocatalytic activity as compared to the catalysts prepared by the conventional method. It was also found that the ultrasound-assisted technique is an energy efficient method as it saves more than 80% of energy along with a substantial reduction in reaction time, as compared to conventional synthesis technique.

6

Authors: Surya Kumar Vatti, Krishnamurthy Konda Ramaswamy, Viswanathan Balasubramanaian

Palladium nano particles in tetrahedral (Td), octahedral (Oh) and spherical (Sp) shapes, supported on hydrotalcite, were synthesized and characterized by XRD and TEM. Td shaped Pd nano particles, with maximum number of exposed (111) planes of Pd, display maximum turn over frequency (TOF) / intrinsic activity for hydrogenation of cinnamaldehyde, indicating the importance of active site geometry. Oh & Sp shaped Pd nano particles that expose both (111) and (100) planes have relatively lower intrinsic activity. For a given reaction, it is essential that appropriate active site geometry, as dictated by the shape/morphology of nano particles be made available. Synthesis and stabilization of such shape controlled nano particles is of prime importance in developing catalysts with higher activity.

8

Authors: J.Vilana, M. Montiel, N. Gimeno, E. Gómez, E. Vallés

Pt-Co thin films have been prepared by means of electrodeposition method, due to the interest of this alloy as catalyst in acid fuel cells. As the stability of the catalyst is fundamental to consider its applicability, the behavior of the films as a function of the composition during voltammetry activation in acidic medium has been studied. The Pt3Co films show high stability, maintaining their morphology, X-ray diffraction profile, composition and high surface area, and show good catalytic behaviour for methanol electro-oxidation in acidic medium. However, the Pt0.7≤x≤1Co films present low stability and evolve during the test to flatter films of lower effective area and Pt3Co stoichiometry, by losing cobalt. Only Pt-Co electrodeposited films of defined compositions show the enough stability and properties to be used as good materials for electro-oxidation processes in acidic media.

14

Authors: Ajalesh Balachandran Nair, Dhanya Vijayan, Ayswarya E P, Rani Joseph, Changwoon Nah

Aluminium hydroxide (ATH) particles were incorporated at different loadings into fluorocarbon rubber (FKM), to study the effect of filler loading on the cure characteristics, mechanical properties, dynamic mechanical properties and thermal stability. The mechanical properties of FKM/ATH composites were better than medium thermal black filled vulcanizates. The storage modulus (E’) of the composites was found to increase due to the enhancement in stiffness. The viscoelastic properties revealed that there is a strong interaction between the polymer and the filler. The dielectric permittivity, AC conductivity and absorption coefficient of the highly ATH loaded systems are much greater than the unfilled and lower systems.

9

Authors: Peitao Liu, Qiang Xu, Daqiang Gao, Shoupeng Shi, Baorui Xia

Visible light-responsive Fe3O4@g-C3N4 nanocomposites were prepared by hydrothermal method with g-C3N4 nanosheets as the substrates. The photocatalytic performances of the Fe3O4@g-C3N4 nanocomposites were evaluated in photo Fenton-like discoloration of RhB dye using H2O2 as an oxidant under visible-light irradiation. Meanwhile, the reusability and magnetic properties were also investigated. The results revealed that the Fe3O4@g-C3N4 nanocomposites showed considerable photocatalytic activity, and exhibited excellent reusability with almost no change after four runs, and more importantly, Fe3O4@g-C3N4 nanocomposites could be recovered magnetically. Therefore, the fabricated Fe3O4@g-C3N4 nanocomposite photocatalyst is a promising candidate for energy conversion and environmental remediation.

11

Authors: Xin-Hua Tian, Yu-Hua Wang, Feng Wei, Xiao-Ning Lin, Lei Ren

An excellent gene vector is of great importance for the development of the gene therapy. Gelatin–siloxane nanoparticles (GS NPs) with controlled size and surface charge were synthesized through a two-step sol–gel process for gene vector. In order to increase the efficiency of tumour targeting, HIV-derived Tat peptide and TTA1, a kind of modified RNA aptamer, were further grafted onto GS NPs (GS-PEG-TTA1/TAT NPs). It was demonstrated in this article that gelatin-siloxane nanoparticles (GS NPs) have the significant characteristic of being innocuous, small, covered with positive charge and even have been modified with PEG, TTA1, and TAT. The modified nanoparticles, GS-PEG-TTA1/TAT, not only have the ability of crossing the cell membrane with DNA accompanied effectively, but also could target the U251 cells and impel the DNA express right in the cells with the help of aptamer TTA1.

18

Authors: Gladius Lewis

Several shortcomings of the alloys that are used to fabricate a number of currentgeneration biomedical implants, such as Ti-6Al-4V alloy for the femoral stem of a total hip replacement and AZ3 Mg alloy for the scaffold of a fully bioabsorbable coronary artery stent, are well-known. Examples of these shortcomings are limited bioactivity/osseointegration (in the case of Ti-based alloys) and high corrosion rate (in the case of Mg-based alloys). It is now recognized that a nanostructured hydroxyapatite (nanoHA) coating on the substrate of a bioalloy can increase bioactivity and reduce corrosion of the substrate. A large number of nanoHA deposition methods and a variety of characterization techniques/methods have been used to obtain an assortment of properties of the coating, the coated specimens, and the coating-substrate interface. Examples of these deposition methods are electrophoretic deposition and radiofrequency magnetron sputtering and some of the most frequently used characterization techniques/methods are x-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, immersion tests in a biosimulating solution at 37 o C, and culturing in cells extracted from humans. Among the properties obtained are the morphology, thickness, size of the nanoHA; degree of crystallinity of the coating; and the adhesive strength and corrosion rate in an aqueous biosimulating solution at 37o C. The present work is a comprehensive review of the very large body of literature in this field, with the focal topics being essential steps in a deposition method, discussion of the influence of deposition method variables on myriad coating properties (for a given deposition method), and identification of the shortcomings of the literature, and, hence, outlines of ten suggested directions for future research.