Nanomaterials & Nanotechnology
Arunkumar M Lahgashetty; Jayasurya K H; Swathi M; Netravati G; Leelanagalaxmi H; Chitralekha Alur; Sangappa K Ganiger
Abstract
Synthesis of nanosized materials integrates the materials synthetic technology. Nanosized bimetallic oxides constitute class materials in concerned with its applications. The present work reports the synthesis of barium stannate (BaSnO3)nanopowder by self-propagating combustion reaction using polyvinyl ...
Read More
Synthesis of nanosized materials integrates the materials synthetic technology. Nanosized bimetallic oxides constitute class materials in concerned with its applications. The present work reports the synthesis of barium stannate (BaSnO3)nanopowder by self-propagating combustion reaction using polyvinyl alcohol (PVA) as a fuel. Initially basic oxides barium oxide (BaO) and tin oxide (SnO2) are also prepared by combustion route. Further barium stannate-PVA nanocomposite (BaSnO3-PVA) is prepared by dispersion of BaSnO3 material into PVA matrix using solvent casting method. Structural characterization of oxide and nanocomposite was studied by X-ray diffraction (XRD) tool and bonding nature by Fourier transfer infrared study (FT-IR) respectively. Thermal behavior of both the sample is well studied by thermo gravimetric analysis (TGA). Electrochemical study of the sample is carried out by cyclic voltammetry (CV) instrumentation. Varied morphology and particle size of the sample was analysed through Transmission electron microscope (TEM) tool.
Maria-Beatrice Coltelli; Vito Gigante; Luca Panariello; Laura Aliotta; Pierfrancesco Morganti; Serena Danti; Patrizia Cinelli; Andrea Lazzeri
Abstract
Chitin nano-fibrils, obtained by waste sea food (for example exoskeletons of crustaceous), are available as water diluted nano-suspensions. Hence, their dispersion at the nanoscale in a molten polyester matrix is considered an issue, because diluted liquids cannot be usually added easily in most common ...
Read More
Chitin nano-fibrils, obtained by waste sea food (for example exoskeletons of crustaceous), are available as water diluted nano-suspensions. Hence, their dispersion at the nanoscale in a molten polyester matrix is considered an issue, because diluted liquids cannot be usually added easily in most common extruders. In the present paper the use of poly(ethylene glycol) (PEG) of different molecular weight was investigated to prepare solid pre-composites useful to disperse chitin nanofibrils in poly(lactic acid) (PLA) by extrusion. The tensile properties of injection moulded specimens were determined and insights were also provided regarding the thermal characteristics of chitin nanofibril-reinforced nanocomposites. This study allowed the identification of a process leading to transparent PLA-based nanocomposites suitable to be exploited in packaging and personal care applications, where the intrinsic anti-microbial and tissue regenerative properties of chitin nanofibrils can be greatly useful.
Kandasamy G Moodley
Abstract
In view of the fact that corrosion costs large sums of money and touches countless facets of human activities, every possible effort needs to be made to find ways to stop it from starting. In this regard inhibition of corrosion has become a thriving commercial activity, worldwide. Much research has been ...
Read More
In view of the fact that corrosion costs large sums of money and touches countless facets of human activities, every possible effort needs to be made to find ways to stop it from starting. In this regard inhibition of corrosion has become a thriving commercial activity, worldwide. Much research has been devoted to discovering newer strategies to inhibit corrosion with concomitant improvements in corrosion inhibition materials. This review will focus on the advances in materials and technologies for corrosion inhibition, with particular attention to the evolution of technologies and materials prior to the advent of coatings, the exploitation of ‘green methods’ which use anti-corrosion materials, which protect materials without fouling the environment; and the present and projected role of nanotechnology in inhibition of corrosion. This review brings together the collected wisdom of several disciplines. The latter addressed and/or are continuing to address the need for cost-effective materials to protect strategic metals used in the domestic and industrial sectors of most countries. The scope for improving the quality of materials, required for shielding these metals from the ravages of degrading agents, present in the environments of most cities, is lucidly articulated.
Zhenya Jiang; Yao Wang; Lifeng Yan
Abstract
WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic ...
Read More
WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic acid groups existed on the surface of graphene nanosheets. In addition, TEM image of WO3@GR indicates that the WO3 nano-particles in size of 5-10 nm have an uniform distribution on the surface of the graphene nanosheets. The as-prepared nanocomposite can be used as a catalyst for biomass conversion, and the catalytic hydrolysis of fructose was carried out at different experiment conditions, such as reaction temperature, reaction time and catalyst dosage. HPLC has been used to measure the compounds in product and their yield. It was found that the major products include HMF, formic acid, lactic acid, acetic acid, and maleic acid, and the maximum yield is 43.25% when the reaction was carried out at 160 o C with the ratio of fructose to catalyst is 8 in the presence of 20 ml of water for 2h. The results reveal that the WO3@GR nanocomposite is a potential catalyst for biomass conversion.
Fokotsa V. Molefe; Mohammed Khenfouch; Mokhotjwa S. Dhlamini; Bakang M. Mothudi
Abstract
As the world demand for energy continue to increase, it is vital to improve renewable energy technologies that will replace conventional fossil fuels. Carbonaceous graphene oxide (GO) is a promising nanomaterial, easy to prepare and scale up to commensurate with industrial requirements. The nanocomposite ...
Read More
As the world demand for energy continue to increase, it is vital to improve renewable energy technologies that will replace conventional fossil fuels. Carbonaceous graphene oxide (GO) is a promising nanomaterial, easy to prepare and scale up to commensurate with industrial requirements. The nanocomposite was prepared in the form of layered structure of GO nanomaterials and poly (3-hexylthiophene) (P3HT) for photovoltaic applications. The X-ray diffraction (XRD) revealed the interaction of P3HT with GO through decrease in lattice spacing. It was evident from scanning electron microscopy (SEM) that the presence of P3HT in GO modified flower like structure to the flaky structures. The interaction of GO with P3HT is presented by various vibrational frequencies in Fourier Transform infrared spectroscopy (FTIR). The increased absorbance and broadening of absorption was observed in the UV-vis spectrum for nanocomposite due to ionic interaction between P3HT and GO. The tunable photoluminescence (PL) measurements showed quenching and shifting of emission spectrum due to charge and energy-transfer. The nanocomposite establish the formation and existence of energy levels upon interaction of GO with P3HT which enhances charge transport. This work provides the direction on coating of thin films for photovoltaic device fabrication. Copyright © 2017 VBRI Press.
Samuel O.B. Oppong; William W. Anku; Sudheesh K. Shukla; Poomani P. Govender
Abstract
La-TiO2-GO nanocomposites were successfully synthesised via sol-gel method. Structures, morphologies and photocatalytic activities of the as-synthesized nanocomposites were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (RS) and scanning electron ...
Read More
La-TiO2-GO nanocomposites were successfully synthesised via sol-gel method. Structures, morphologies and photocatalytic activities of the as-synthesized nanocomposites were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (RS) and scanning electron microscopy (SEM). UV-Vis diffuse reflectance spectroscopy was used to estimate band gap energies. The photocatalytic activities of the as-synthesized nanocomposites were evaluated for the degradation of Acid Blue 40 in aqueous solutions under simulated solar light. The photocatalytic results show that the as-synthesized La-doped TiO2-GO (0.3% La) nanocomposite shows good photocatalytic activity and can be considered as a promising photocatalyst for the degradation of organic pollutants in water. The good photocatalytic efficiency is ascribed to the cooperative effect of improved visible light absorbance and separation of charge carriers due to the combined effect of La and the GO in the composite. Analysis from Total organic carbon (TOC) shows a high degree of complete mineralisation of Acid Blue 40 (TOC removal of 75%) which decreases the formation of possible degradation by-products. Due to the stability of La-TiO2-GO (0.3% La) nanocomposite, it was reused for five times reaching 84.0% maximum degradation efficiency during the five cycles.
P. V. Ramana; A. Viswadevarayulu; K. Kumar; S. Adinarayana Reddy
Abstract
The potential of a novel photocatalyst graphene-ZnO (G-ZnO) obtained from graphene oxide and zinc acetate dihydrate was investigated for the reduction of heavy metal Cr(VI) ions from water. In which ZnO nanocubic crystals were finely doped on the graphene sheets, was well done by facile wet chemical/reflux ...
Read More
The potential of a novel photocatalyst graphene-ZnO (G-ZnO) obtained from graphene oxide and zinc acetate dihydrate was investigated for the reduction of heavy metal Cr(VI) ions from water. In which ZnO nanocubic crystals were finely doped on the graphene sheets, was well done by facile wet chemical/reflux method under N2 atmosphere. Due to hindered nature of photo-generated electron-hole pair recombination and enhanced light absorption shows efficient photocatalytic performance of G-ZnO nanocomposites (NCs) in the reduction of Cr(VI) ions with a degradation rate of 98% under daylight illumination as related with bare ZnO (42%), graphene oxide (GO) (19%) and mechanical mixture GO+ZnO (62%). The overall results demonstrated that the photocatalyst used in this study, is promising, efficient and economical when used to separate heavy metal ions from water.
Nelson H. A. Camargo; Eliakim E. G. de Borba; Priscila F. Franczak; Enori Gemelli
Abstract
Microporous calcium phosphate biomaterials are known for their physical and biological applications. Among the best known are the stoichiometric hydroxyapatite (HA) and tricalcium phosphate (TCP). This is because these biomaterials exhibit chemical and crystallographic compositions which are similar ...
Read More
Microporous calcium phosphate biomaterials are known for their physical and biological applications. Among the best known are the stoichiometric hydroxyapatite (HA) and tricalcium phosphate (TCP). This is because these biomaterials exhibit chemical and crystallographic compositions which are similar to that found in bones and teeth. The use of nanotechnology enables obtaining calcium phosphate nanostructured powders and calcium phosphate nanocomposite matrix formed by a second nano phase of type SiO2, TiO2, Al2O3-a, ZrO2, Mg. Different methods and techniques for the synthesis and preparation of nanostructured powders and biomaterials are noted in the literature, but it is known that not all lead to the same results. Calcium phosphates nanostructured biomaterials are a new class of biomaterials which provide new physical, morphological, nanostructural and microstructural features with interconnected microporosity which are promising to wettability, capillary action, cell adhesion and proliferation on the surface of grains and micropores. Based on research of these biomaterials, it has been found that they show potential applications in traumatology, orthopedic and dental applications in reconstruction, defects and bone tissue repairing, implants attachment and dental remineralization treatment. This study was aimed at the sintering and characterization of an HA matrix and three nanocomposite biomaterials with 5% by volume of the respective second phases: SiO2, ZrO2 and Al2O3-a in the HA matrix. The HA powder and nanocomposite HA/SiO2 were sintered at 1100 °C/2h. HA/ZrO2 nanocomposite powder followed two sintering conditions: a temperature of 1100 °C/2h and the other, at 1300 ºC/2h. HA/Al2O3-a nanocomposite powder was only sintered at 1300 ºC/2h. The biomaterials were characterized by scanning electron microscopy, X-ray diffraction and open porosity and hydrostatic density were also determined by applying the Arthur method. The results are encouraging and show for HA, HA/SiO2, HA/ZrO2 biomaterials (obtained by sintering at 1100 °C) interconnected microporous microstructures, formed by fine grains which are favorable for the expected wettability and capillarity characteristics.
Somit Kumar Singh; Ananda Murthy H. C; Vandana Singh
Abstract
In the present investigation, the remediation of mercury by using the gum acacia-silica composite as an adsorbent has been studied. Experiments revealed optimum parameters which were found to be pH 6, contact time 2 hours, Hg(II) concentration of 100 ppm, reflux temperature 30 0 C and adsorbent dosage ...
Read More
In the present investigation, the remediation of mercury by using the gum acacia-silica composite as an adsorbent has been studied. Experiments revealed optimum parameters which were found to be pH 6, contact time 2 hours, Hg(II) concentration of 100 ppm, reflux temperature 30 0 C and adsorbent dosage of 50 mg. The experimental data was subjected to modeling using the Langmuir and Freundlich isotherms. It was found that the data very well fitted to the Freundlich model. The pseudo second order kinetics confirms chemisorption with rate constant 3.1 × 10-4 gmg-1min-1. The calculated thermodynamic parameters (?G 0 , ?S 0 , ?H 0 ) revealed the exothermic and spontaneous nature of adsorption process at the solid–solution interface. The adsorbent could be recycled for six successive cycles with 31.5% loss in its efficiency. The adsorbent is found to be highly effective and economical for mercury remediation from water.
Rabia Sattar; Ayesha Kausar; Muhammad Siddiq
Abstract
Polyurethane/polythiophene (PU/PTh) blends and nanocomposites were prepared by solution mixing and in situ polymerization, respectively and were investigated for mechanical, thermal, electrical and shape memory properties. Formation of blends and composites was supported by FTIR analysis. Surface morphology ...
Read More
Polyurethane/polythiophene (PU/PTh) blends and nanocomposites were prepared by solution mixing and in situ polymerization, respectively and were investigated for mechanical, thermal, electrical and shape memory properties. Formation of blends and composites was supported by FTIR analysis. Surface morphology of prepared samples was clarified by scanning electron microscopy (SEM). Homogeneous morphology of the composites was observed compared to blends due to well dispersion of NH2 functionalized MWCNTs attributed to introduction of urea linkages between the functionalized nanotubes and the NCO-terminated PU. Smooth morphology of the composites resulted for the significant improvement of the mechanical properties. Thermal stability of the blends and composites was found increased with PTh content. According to differential scanning calorimetry (DSC), an increase in glass transition, melting and crystallization temperature was observed for composites with PTh addition. Maximum shape recoverability (92 %) was exhibited by the PU/PTh composite with 1 wt. % PTh loading.
K. Sangeetha; Y. Yokogawa; E.K. Girija
Abstract
In recent decades bone infection is one of the most challenging issues encountered in biomedical field and local antibiotic delivery is a key strategy to overcome this issue. Hence developing bioactive materials in combination with antibiotics is much focused recently for bone substitutes. Here we report ...
Read More
In recent decades bone infection is one of the most challenging issues encountered in biomedical field and local antibiotic delivery is a key strategy to overcome this issue. Hence developing bioactive materials in combination with antibiotics is much focused recently for bone substitutes. Here we report the fabrication of pristine and natural polymer (gelatin) composite matrices of hydroxyapatite (HA) by a facile wet precipitation method and their drug release behavior from directly loaded and in situ loaded matrices using amoxicillin as the model drug. The products thus obtained were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG) and scanning electron microscopy (SEM) which confirmed the formation of HA and nanocomposite of HA with gelatin. It was observed that under physiological conditions, for sustained and prolonged release of the drug in situ loading in composite matrix is a favorable approach.
R. Sriramprabha; M. Divagar; D. Mangalaraj; N. Ponpandian; C. Viswanathan
Abstract
Pristine SnO2 and SnO2/Graphene (SnO2/GN) nanocomposites were prepared via facile hydrothermal method with amended electro catalytic activity towards Dopamine (DA) sensing. X-Ray Diffraction (XRD) pattern revealed the formation of tetragonal crystal system of SnO2 that was retained in both pure metal ...
Read More
Pristine SnO2 and SnO2/Graphene (SnO2/GN) nanocomposites were prepared via facile hydrothermal method with amended electro catalytic activity towards Dopamine (DA) sensing. X-Ray Diffraction (XRD) pattern revealed the formation of tetragonal crystal system of SnO2 that was retained in both pure metal oxide and composite. Fourier Transform – Infrared (FT-IR) transmission spectra evidenced the stretching and bending vibration modes of pure SnO2 and SnO2/GN nanocomposites. The in-plane bending modes of SnO2 and graphatic peaks in graphene oxide (GO) and composite were identified in Raman spectral analysis. Morphology of synthesized materials and uniform distribution of SnO2 on graphene sheet in SnO2/GN composite were observed in Field Emission-Scanning Electron Microscope (FE-SEM). Electrochemical performance of SnO2 and SnO2/GN nanocomposite on modified Glassy Carbon (GC) electrode was evaluated for direct DA sensing using Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV) and Chrono Amperometric techniques. The SnO2/GN nanocomposite showed enhanced charge carrier mobility towards DA in presence of interferences like Ascorbic acid (AA) and Uric acid (UA) compared to pristine SnO2. The limit of detection was calculated as (0.7μM) for (SnO2/GN) which is better than bare SnO2 (6.675 μM). These synergetic behaviors depicting SnO2/GN composite can serve as a promising electrode in sensor transducers in near future.
Soumya Mukherjee; Manoj Kumar Mitra
Abstract
Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical ...
Read More
Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical route by blending of Nickel ferrite as second phase on Bismuth ferrite after heat treatment at 500 °C for 2, 3 and 4 hours soaking period. From the diffractogram data of XRD, the phase, and planes of orientation are analyzed of the synthesized materials. The crystallite size is calculated by Scherrer’s formula. FESEM studies reveal the morphological features having interconnected agglomerates with spherical, irregular polygonal or some elongated shape of the synthesized nanocomposite. FTIR result shows the molecular signature of the nanocrystalline material to verify the M-O coordination. Interplanar spacings and SAED pattern are revealed from HRTEM images which are very close to the experimental findings from XRD phase analysis. UV-VIS analysis is performed in the transmission mode of spectra within the scan range of 200-1100 nm. From the spectra, using Tauc relation band gap is calculated. Band gap are found of the order of 2.847 eV, 2.78 eV, 2.69 eV respectively for 2, 3 and 4 hours soaking period close to semiconducting material. With the increase of soaking time band gap is found to decrease following Arrhenius activation of electronic mobility overwhelming the energy barrier at respective lattice sites. M-H analysis of Nanocomposite at 500 °C for 2 hrs is closer towards ferromagnetic with incomplete loop but for sample at 500 °C for 4hrs it is closer towards superparamagnetic one. The property of this material reflects it has many interesting characteristics suitable for opto-electronic, photo-magnetic devices and other electronic applications.
Minh-Tai Le;Shyh-Chour Huang
Abstract
The main objective of this work is to conduct a manufacturing experiment on a single-walled carbon nanotube (SWCNT)/polyester nanocomposite for characterization of its mechanical properties using a tensile test and nanoindentation techniques. Experimental specimens were made under identical conditions ...
Read More
The main objective of this work is to conduct a manufacturing experiment on a single-walled carbon nanotube (SWCNT)/polyester nanocomposite for characterization of its mechanical properties using a tensile test and nanoindentation techniques. Experimental specimens were made under identical conditions using the hot press process. Dispersion of SWCNTs in an unsaturated polyester matrix was conducted by a sonication method, and a high-speed shear mixer was used for mixing the curing agent and resin. Following the manufacturing of the SWCNT/polyester nanocomposites, characterization of the mechanical properties of the material was performed by tensile testing and nanoindentation techniques. In addition, the morphologies of the fractured surface of SWCNT/polyester nanocomposites were observed with a scanning electron microscope (SEM). The results of mechanical tests exhibit improvements of Young’s modulus and hardness by 35% and 29%, respectively, at 1.0 wt% SWCNTs. In addition, the elastic modulus determined by the nanoindentation technique differs from the one obtained from tensile tests by 16%. The experimental samples are expected to yield the novel promising materials that offer a low-cost, high-strength material for use in the manufacture of lightweight components for automobiles, transportation systems and consumer products.
Vandana Singh; Somit Kumar Singh
Abstract
In present communication we report on Cd(II) adsorption using our recently reported material, the guar gum-silica nanocomposite. The equilibrium, thermodynamics and kinetics of Cd(II) adsorption onto composite from aqueous solution were investigated. Optimum experimental parameters were determined to ...
Read More
In present communication we report on Cd(II) adsorption using our recently reported material, the guar gum-silica nanocomposite. The equilibrium, thermodynamics and kinetics of Cd(II) adsorption onto composite from aqueous solution were investigated. Optimum experimental parameters were determined to be pH 8, contact time 2 hours, Cd(II) concentration 100 mg/L, temperature 30 o C and adsorbent dose 10 mg. The sorption equilibrium data were modeled using the Langmuir and Freundlich isotherms where the data fitted better to Langmuir model indicating unilayer sorption, the Qmax being 666 mg/g. The kinetic data indicated chemisorption in the rate-controlling step as the pseudo-second-order model was best suited (rate constant of 2.79 × 10-4 gmg -1 min -1 at 100 mg/L Cd 2+ ). The calculated thermodynamic parameters (ΔG°, ΔS°, ΔH°) showed the adsorption to be exothermic and spontaneous with decreased randomness at the solid–solution interface. The adsorbent could be recycled for six successive cycles with 31% loss in its efficiency.
Neeta Pandey; S.K. Shukla; N.B. Singh
Abstract
Copper is widely used in different industries and found its significant loss during the manufacturing and processing. The lost Cu is discharged in the effluent, thus adsorption of heavy metals is an important technology for treatment of wastewater containing different types of selected heavy metals. ...
Read More
Copper is widely used in different industries and found its significant loss during the manufacturing and processing. The lost Cu is discharged in the effluent, thus adsorption of heavy metals is an important technology for treatment of wastewater containing different types of selected heavy metals. In this study, nanosize (~95 nm) zinc oxide was prepared through KNO3-NaNO3 eutectic melt at 450 °C. The obtained ZnO was encapsulated in urea-formaldehyde (UF) resin during acid catalysed polymerization process. The characterization of ZnO and ZnO-UF were made by X- ray diffraction (XRD), Scanning electron microscope (SEM) and Infra red spectroscopic (FT-IR) techniques. The prepared ZnO encapsulated in urea-formaldehyde resin casted in the form of film (~0.5 mm thickness) was used to remove 80% Cu (II) content from aqueous solution in 15 minutes. Further, the adsorption process was investigated and data was explained with Langmuir adsorption isotherm model.
Hardeep Kumar; L. Olivi;G. Aquilanti; S. Ghosh; P. Srivastava; D. Kabiraj; D. K. Avasthi
Abstract
A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present ...
Read More
A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe 0 , Co 0 ) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H2 environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O4 and CoFe2O4 phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H2 environment annealing (450-700 o C) leads to formation of bcc FeCo alloy.
Surender Duhan; B.S. Dehiya;Vijay Tomer
Abstract
Sol–gel chemistry has recently attracted a large attention with a view of preparation of silver-silica nano-composites for photo-catalytic applications. This method of synthesis allows glassy materials to be prepared at a much lower temperature than the traditional melt-glass techniques. Moreover, ...
Read More
Sol–gel chemistry has recently attracted a large attention with a view of preparation of silver-silica nano-composites for photo-catalytic applications. This method of synthesis allows glassy materials to be prepared at a much lower temperature than the traditional melt-glass techniques. Moreover, it enables higher doping concentrations and a more uniform distribution of silver in the glass host matrix to be achieved. This method produces large quantities of amorphous gels that are thermal treated in air at the temperature of 500°C for one hour. The silver-silica samples were investigated through X-ray diffraction (XRD for the determination of their microstructure, phase and compositions. It is found that the microstructure depends closely on the solution pH and the extent of silver-doping. MB dye degradation by undoped and Ag doped SiO2 was studied under UV and Visible light irradiation. The results are intriguing as the doping by Ag produces opposite effects on photocatalytic degradation rates under the two conditions.
Laxmi J. Tomar; B.S. Chakrabarty
Abstract
A series of TiO2-ZrO2 mixed oxide samples with various ZrO2-TiO2 content (10, 30, 40, 60, 70 and 90 mol %) were prepared by hydrothermal method. These nanocomposites were characterized by XRD, SEM, UV-vis spectroscopy and Photoluminescence spectroscopy. XRD data identified Anatase and Rutile phases in ...
Read More
A series of TiO2-ZrO2 mixed oxide samples with various ZrO2-TiO2 content (10, 30, 40, 60, 70 and 90 mol %) were prepared by hydrothermal method. These nanocomposites were characterized by XRD, SEM, UV-vis spectroscopy and Photoluminescence spectroscopy. XRD data identified Anatase and Rutile phases in the TiO2 rich samples while Tetragonal and Monoclinic phases in ZrO2 rich samples. The average crystallite size of the samples was between 9 to 26 nm. As per Uv-Vis spectra, the band gaps of TiO2-ZrO2 composites vary from 1.34 eV to 2.48 eV. The absorption spectra show a shift of the absorption edge of TiO2-ZrO2 towards longer wavelength region. The decreased band gap is attributed to the surface trap states. The PL spectrum shows very strong blue-green PL band under excitation at 300 nm. The occurrence of emission peaks in the visible region is attributed to the presence of defect levels below the conduction band.
Saruchi Surbhi; Praveen Aghamkar; Sushil Kumar
Abstract
Nanomaterials and nanostructures have received steadily growing interests as a result of their peculiar and fascinating properties and applications. Neodymia-silica nanocomposites were prepared by sol-gel route followed by calcination. The samples were prepared with different concentration of dopant ...
Read More
Nanomaterials and nanostructures have received steadily growing interests as a result of their peculiar and fascinating properties and applications. Neodymia-silica nanocomposites were prepared by sol-gel route followed by calcination. The samples were prepared with different concentration of dopant (Nd2O3) and calcined in a programmable furnace at 1000 °C for 5 h. The structural evolution of samples was investigated by employing techniques such as XRD, FTIR and TEM. X-ray diffraction patterns showed that the samples were nanocrystalline and the size of crystallites has been determined using Debye-Scherrer relation. The FTIR spectra confirmed the presence of functional groups of prepared material. The particle size of samples was also estimated through TEM analysis. It has been observed that crystallinity as well as particle size of the samples increases with increase in dopant concentration.
)
)
)