Research Article
Shailesh Narain Sharma; Parul Chawla; Shefali Jain; Mansoor Ahamed; N. Vijayan; J. Sharma
Abstract
In this present work, Cu2ZnSn(Se1-x,Sx)4 nanocrystals with tunable band gaps have been synthesized via hot injection method in conjunction with TOP/TOP capping ligands. By varying the input precursor ratio Se/( S + Se), by adjusting the composition parameter x from 0 to 1.0, the band ...
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In this present work, Cu2ZnSn(Se1-x,Sx)4 nanocrystals with tunable band gaps have been synthesized via hot injection method in conjunction with TOP/TOP capping ligands. By varying the input precursor ratio Se/( S + Se), by adjusting the composition parameter x from 0 to 1.0, the band gaps of the CZTSSe-based nanocrystals can be linearly tuned from 1.2 to 1.5 eV respectively. For CZTSSe-based nanocrystals, high intensity of XRD peak corresponding to (112) direction revealed that the growth is oriented along (112) direction and its intensity increases with increase in Se/(S + Se) input precursor ratio. As the Se-content increases, the larger Se atoms (1.98 Å) replace the smaller larger S atoms (1.84 Å) resulting in an increase in the lattice parameters as shown by the shift of the XRD peaks to lower values of 2θ.XRD studies reveal the presence of stable kesterite phase although the presence of either stannite phase or both cannot be ruled out completely. It has been found that CZTSSe nanocrystallites owing to its high crystallinity and well-ordered 3-dimensional network and hence controlled morphology in its pristine form as compared with CZTSe, CZTS counterparts exhibits higher homogeneity, resistance against agglomeration and eventually higher current-voltage characteristics. To, the best of our knowledge, this is the first detailed report on the synthesis of multicomponent Cu2ZnSn(Se1-x,Sx)4 nanocrystals by hot injection method via the usage of both TOP (trioctyl phosphine) & TOPO (trioctyl phosphine oxide) capping ligands. The primary technological advantage of creating nanocrystals by this solution based method is the capability to easily form an ink that is compatible with a large variety of scalable film formation or printing processes for photovoltaic applications. Copyright © 2016 VBRI Press.
Ravindra Kumar Jha; Raghubeer Singh; Debasree Burman; Sumita Santra; Prasanta Kumar Guha
Volume 1, Issue 2 , 2016, Pages 125-130
Abstract
We report herein exfoliation of WS2, which is one of the most promising but less investigated among 2D TMDs in binary mixture of diethyl ether (with boiling point=34.6°C) and water. The bulk WS2 powder was first ball milled in toluene for few minutes and at low rpm. Subsequently the powder was kept ...
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We report herein exfoliation of WS2, which is one of the most promising but less investigated among 2D TMDs in binary mixture of diethyl ether (with boiling point=34.6°C) and water. The bulk WS2 powder was first ball milled in toluene for few minutes and at low rpm. Subsequently the powder was kept at 4°C for 20 hours in binary mixture of diethyl ether and water with their volume fraction varying from 10% to 90%, before taking for the ultrasonication. It should be noted that neither diethyl ether nor water is capable of disperse WS2 alone. Ultrasonic waves generate cavitation bubbles that collapse into high-energy jets, breaking up the layered crystallites and producing exfoliated nanoflakes. Hansen Solubility Parameters (HSP) for the binary mixture has been calculated and the mixture which minimizes the Hansen distance has been selected for further characterization of few layered nature of thin sheets. Field emission scanning electron microscopy (FESEM) has been utilized to monitor the progress in exfoliation at different stages. Atomic force microscopy (AFM) confirms the formation of <8nm thin sheets with lateral dimension of few hundred nm. Raman spectroscopy has been utilized for further confirmation. Transmission electron microscopy (TEM) has been utilized to show the crystallinity of nanosheets which agrees with the X-ray diffraction results. Ultra-violet-visible (UV-Vis) and Fourier transform infrared (FTIR) have been used as spectroscopy tools throughout the work. This exfoliation technique is unique in the sense of producing pristine nanosheets due to the involvement of very low boiling point solvents.
Research Article
Pragya Pandit; Pargin Bangotra
Abstract
In this paper we investigate the effect of lanthanum doping on structural, dielectric and electrical properties of lead magnesium niobate - lead titanate, 0.65Pb(Mg1/3Nb2/3O3)- 0.35PbTiO3 (x=0, 0.02, 0.05) ferroelectric ceramics. Dielectric and AC impedance spectroscopic measurements were ...
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In this paper we investigate the effect of lanthanum doping on structural, dielectric and electrical properties of lead magnesium niobate - lead titanate, 0.65Pb(Mg1/3Nb2/3O3)- 0.35PbTiO3 (x=0, 0.02, 0.05) ferroelectric ceramics. Dielectric and AC impedance spectroscopic measurements were carried out on pure and lanthanum doped PMN/PT ceramics over a wide temperature (30o- 450o C) and frequency interval (10 Hz-1 MHz). Pure and lanthanum doped Pb1-xLax[(Mg1+x/3Nb2-x/3)0.65Ti0.35(1-x/4)]O3, (x=0, 0.02, 0.05) ceramics were prepared by solid state reaction route using columbite precursor method. X-ray diffraction revealed tetragonal (P4mm) phase for pure PMN/PT ceramics and transition to pseudo cubic phase (Pm3m) was observed with increased lanthanum doping. The dielectric response of the lanthanum modified PMN/PT ceramics was interpreted in terms of modified curie weiss law. Modulus spectroscopy revealed the deviation of dielectric behavior from ideal Debye behaviour. Activation energies calculated from dielectric relaxation and modulus spectroscopy suggested that charge transport processes are due to oxygen ion hopping.The AC conductivity of the PMN/PT ceramics initially increased for 2 mol% of lanthanum doping followed by a subsequent decrease with further 5 mol% of lanthanum doping. The value of the activation energies calculated from the temperature dependance of ac conductivity was in the range from 1.20-1.48 ev which is due to doubly ionized oxygen vacancies. The overall structural, electrical and dielectric behaviour of Pb1-xLax[(Mg1+x/3Nb2-x/3)0.65Ti0.35(1-x/4)]O3, (x=0, 0.02, 0.05) ceramics is correlated to the relaxor nature induced by lanthanum doping.
Research Article
Ajoy K. Saha; Rajesh Kumar; Belal Usmani; Laltu Chandra; Ambesh Dixit
Abstract
We report the development of Fe3O4/Cu, and Ni-Fe3O4/Cu based spectrally selective coatings for solar absorber applications using two different electrochemical baths. The deposition processes were optimized for both electrochemical baths and it was observed that the controlled introduction of nickel in ...
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We report the development of Fe3O4/Cu, and Ni-Fe3O4/Cu based spectrally selective coatings for solar absorber applications using two different electrochemical baths. The deposition processes were optimized for both electrochemical baths and it was observed that the controlled introduction of nickel in Fe3O4 matrix is important to achieve enhanced solar thermal response. The fabricated coatings were characterized to understand the structural, micro-structural and optical properties, to investigate their phase, chemical composition, surface morphology, thickness and solar thermal properties. Ni-Fe3O4 composite coatings exhibited improved adhesion to Cu substrate and allowed better thickness control when compared to Fe3O4 structures without Ni. Improved substrate adhesion and optimized thickness resulted in better optical properties for these coatings. The optimized Ni-Fe3O4 coatings exhibit maximum spectrally averaged absorptivity (α = 0.87) in the 300 – 900 nm wavelength range, and minimum spectrally averaged emissivity (ε = 0.18) in the 2.5 – 25 µm infrared range at room temperature. For Fe3O4 coatings developed on Cu substrates without Ni, maximum absorptance and minimum emittance values obtained were 0.76 and 0.08 respectively. Ni-Fe3O4 coating thickness was measured ~32 μm.
Research Article
Basu M. Daas; Debalina Das; Susanta Ghosh
Abstract
Present study reports electro-oxidation of ethanol over platinum loaded, reduced graphene oxide – ZSM-5 composite (GO-ZSM) on graphite foil (GF). To prepare the Pt/r(GO-ZSM)/GF electrode, GO-ZSM-5 composite was prepared by simple 1:1 mechanical mixing which was coated over graphite foil and electrochemically ...
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Present study reports electro-oxidation of ethanol over platinum loaded, reduced graphene oxide – ZSM-5 composite (GO-ZSM) on graphite foil (GF). To prepare the Pt/r(GO-ZSM)/GF electrode, GO-ZSM-5 composite was prepared by simple 1:1 mechanical mixing which was coated over graphite foil and electrochemically reduced at a current density of (-)1 mA.cm-2. The electro-chemical studies, such as cyclic voltammetry and chronoamperometry established that Pt/r(GO-ZSM-5)/GF electrode exhibited better tolerance towards CO-poisoning compared to Pt/rGO/GF electrode. The larger IF:IB value for Pt/r(GO-ZSM)/GF indicated much lesser carbonaceous accumulation on the zeolite modified electrode. The peak current density was comparable for both Pt/r(GO-ZSM-5)/GF and Pt/rGO/GF electrodes. Thus ZSM-5 was instrumental in reducing the catalyst poisoning without compromising with the current density. The findings of the investigation can prove useful in the search of solution for the problem of catalyst poisoning associated with platinum electrodes.
Research Article
Dhanasekaran Prakash; Sellamuthu N. Jaisankar
Abstract
A 2, 4, 6-Tris (4-nitrophenyl) pyridine (TNPP) was synthesized from nitrobenzaldehyde and nitroacetophenone in glacial acetic acid and conformed. The TNPP monomer further reacted with diamines such as benzidine (TNPP-B) and phenylenediamine (TNPP-P) to obtain azo linked polymers for photochemical activity. ...
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A 2, 4, 6-Tris (4-nitrophenyl) pyridine (TNPP) was synthesized from nitrobenzaldehyde and nitroacetophenone in glacial acetic acid and conformed. The TNPP monomer further reacted with diamines such as benzidine (TNPP-B) and phenylenediamine (TNPP-P) to obtain azo linked polymers for photochemical activity. These polymer structures were identified using different characterization techniques like FTIR, UV-visible spectroscopy, scanning electron microscope (SEM), fluorescence spectroscopy, cyclic voltammetry, DSC and TGA. The FTIR spectra of all the azo-linked functional group of polymers were observed at 1592 cm-1 and 1596 cm-1. The TNPP-B based TNPP polymer exhibit high thermal decomposition temperature (Td) at 403 °C. UV/vis absorption spectra for TNPP-B and TNPP-P were absorbed in the region 300-375, 285-385 and 350-400 nm. These polymer materials could be used for optical and energy applications.
Research Article
Amit Srivastava; Naresh Kumar
Abstract
Biosensor for the detection of hydrogen peroxide (H2O2) has been prepared by immobilizing horseradish peroxidase (HRP) enzyme using physical adsorption technique on zinc oxide (ZnO) nanostructures. The (002) oriented ZnO nanostructures as confirmed by X-ray diffraction, were successfully grown on indium ...
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Biosensor for the detection of hydrogen peroxide (H2O2) has been prepared by immobilizing horseradish peroxidase (HRP) enzyme using physical adsorption technique on zinc oxide (ZnO) nanostructures. The (002) oriented ZnO nanostructures as confirmed by X-ray diffraction, were successfully grown on indium tin oxide (ITO) coated glass substrate by pulsed laser ablation (PLA) without using any catalyst. The Nafion solution was added onto HRP/ ZnO/ ITO bio-electrode to form a tight membrane on the surface before carrying out bio-sensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared bio-electrode HRP/ZnO/ITO is highly sensitive to the detection of H2O2 over a wide range of concentration with a linear range from 2.5 μM to 100 μM with the limit of detection 0.2 μM and sensitivity of 0.034 µA/ µM cm2. The higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. A relatively low value of the enzyme’s kinetic parameter (Michaelis-Menten constant, Km) of 0.166 μM indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in bio-sensing, clinical, food and beverage industry.
Research Article
Akanksha Prakash; Shailesh Narain Sharma
Abstract
Indium Phosphide quantum dots (InP QDs) having various applications can be used for both LEDs and photovoltaics owing to its highly luminescent properties and energy harvesting potential respectively. In our work we have synthesized InP QDs using hot injection technique. Further post synthesis treatment ...
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Indium Phosphide quantum dots (InP QDs) having various applications can be used for both LEDs and photovoltaics owing to its highly luminescent properties and energy harvesting potential respectively. In our work we have synthesized InP QDs using hot injection technique. Further post synthesis treatment was given and InP/ZnS core shell nanocrystals were grown on InP core. Composites with P3HT conducting polymer were made in order to study the charge transfer/energy transfer phenomenon. InP and InP/ZnS QDs show an effective phenomenon of energy transfer and PL increment is observed in the case of composites. Whereas in the case of treated InP QDs a decrement in the PL was observed. Treatment results in removal of the surface defects and traps which help in effective charge transfer rather than energy transfer. Post synthesis treatment increases the monodispersity of the QDs which results in high quality QDs without any defects. With a simple post synthesis treatment,InP QDs can be used for both LEDs as well as photovoltaic applications. The future work involves the device fabrication of InP QDs and treated InP QDs for LED and solar cells respectively. Various characterization such photoluminescence, transmission electron microscopy, selected area diffraction was done in order to confirm the charge/energy transfer phenomenon. Copyright © 2016 VBRI Press.
Research Article
Debasree Burman; Ravindra Kumar Jha; Sumita Santra; Prasanta Kumar Guha
Abstract
In our paper, few layered MoS2 nanoflakes were exfoliated from the bulk powder in mixed solvent using a simple sonication assisted liquid exfoliation technique at room temperature. The successful exfoliation of the nanoflakes was characterized using various characterization tools like Scanning Electron ...
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In our paper, few layered MoS2 nanoflakes were exfoliated from the bulk powder in mixed solvent using a simple sonication assisted liquid exfoliation technique at room temperature. The successful exfoliation of the nanoflakes was characterized using various characterization tools like Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Atomic Force Microscopy (AFM). The humidity sensor was fabricated by drop-casting MoS2 nanoflakes on Pt-based Interdigitated Electrodes (IDEs). The sensing was carried out in an in-house gas test setup interfaced with a Semiconductor Parameter Analyzer (SPA) to record the measurements. The response of the sensor was studied by passing different levels of humidity through the gas chamber. The response was found to increase with increase in humidity level and was better than few recently reported results. The maximum response was found to be ~16 times at 75% RH. Since water is an electron donor and MoS2 is inherently n-type semiconductor, the conductivity of the MoS2 sensing layer increased in presence of humidity. The large surface to volume ratio and presence of inherent defects facilitated the adsorption and desorption of a large number of H2O molecules. The response time and recovery time of the sensor was 65 seconds and 72 seconds respectively. Thus we conclude that our MoS2 based humidity sensor with a maximum response of 16 times (75% RH) can act as a low power, highly sensitive and fast humidity sensor in various applications like indoor air quality monitoring, agriculture, semiconductor industry etc.
Research Article
James Mathew; Animesh Mandal; Jason Warnett; Mark A. Williams; M. Chakraborty; Prakash Srirangam
Abstract
The present work compares the 2D and 3D distribution of TiB2 particles in a semisolid processed Al-4.5%Cu-5wt.% TiB2 in-situ composite prepared by flux assisted synthesis. The composite was synthesized by the reaction of K2TiF6 and KBF4 salts in molten Al-4.5Cu alloy held at 800 oC for an hour. The extent ...
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The present work compares the 2D and 3D distribution of TiB2 particles in a semisolid processed Al-4.5%Cu-5wt.% TiB2 in-situ composite prepared by flux assisted synthesis. The composite was synthesized by the reaction of K2TiF6 and KBF4 salts in molten Al-4.5Cu alloy held at 800 oC for an hour. The extent of distribution of TiB2 particles was investigated using Field Emission Scanning Electron Microscopy (FESEM) and X-ray computed tomography (XCT) to obtain 2Dand 3D images respectively. The studies indicated improved distribution of TiB2 particles after semi-solid forging of composites (at 0.1 volume fraction of liquid and 50% reduction) as compared to as cast composites. The hardness of the semisolid forged composites showed a significant increase and is uniform in all directions. The increase in hardness could be attributed to particle fragmentation and its redistribution in the matrix. Further investigation will be needed to understand the mechanism of redistribution and investigate the mechanical properties of such composites in detail. Copyright © 2016 VBRI Press.
Research Article
Asheesh K. Sharma; Jayanth K. Swamy; Anjana Jain
Abstract
Piezoelectric polymer-ceramic composite materials are promising candidate for transducer application because of their inherent capability of combining the favourable properties of both ceramic and polymer materials. Present work discusses the dielectric properties of such composite films developed from ...
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Piezoelectric polymer-ceramic composite materials are promising candidate for transducer application because of their inherent capability of combining the favourable properties of both ceramic and polymer materials. Present work discusses the dielectric properties of such composite films developed from two piezoelectric materials viz. Poly(vinylidene fluoride) (PVDF) as a matrix and Lead Zirconate Titanate (PZT) as filler in PVDF. PVDF-PZT composite films were prepared by solvent casting method followed by hot pressing for better packing and connectivity of ceramic phase in the composite and hence improved piezoelectric properties in the material. The dielectric parameters of these films are evaluated by the measurement of dielectric constants (ε¢ and ε¢¢), intrinsic impedance, capacitance and dielectric loss, etc. as function of frequency at room temperature. The temperature dependence of the dielectric properties is studied as well from 40˚C to 75˚C. It was found that dielectric properties like permittivity and capacitance were quite stable in the frequency range 100 Hz-100 kHz. A variation of 20 to 50% in dielectric properties was observed, for increase in temperature with respect to room temperature, which may be accounted to pyroelectric behaviour of material.
Research Article
Sharmistha Anwar; Barada K. Mishra; Shahid Anwar
Abstract
Thermoelectric thin films of Bi2Te3 and Sb2Te3 were deposited by using sputtering technique. Structural characterizations of as deposited films were done by using X-ray diffraction (XRD), Energy Dispersive X-ray Analysis and electrical properties have been evaluated at room temperature by Seebeck coefficient ...
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Thermoelectric thin films of Bi2Te3 and Sb2Te3 were deposited by using sputtering technique. Structural characterizations of as deposited films were done by using X-ray diffraction (XRD), Energy Dispersive X-ray Analysis and electrical properties have been evaluated at room temperature by Seebeck coefficient and electrical resistivity measurement. These sputtered films were established to be polycrystalline and of desired single phase in nature with stoichiometric composition. The Seebeck coefficient and electrical resistivity of p-type Sb2Te3 thin film and n-type Bi2Te3 thin films were found to be about 111 μV/K, 8.25×10-5 Ω- m and −98.52μV/K, 5.87×10-6 Ω-m, respectively whereas to that of n-type Bi2Te3-Sb2Te3 multilayer having 5BL combination is −145μV/K, 9.31×10-5 Ω-m and 10BLcombination is −170 μV/K, 9.86×10-5 Ω-m. The power factor value has increased reasonably well in case of multilayer as compared to that of individual single layer, maximum power factor value 2.95×10-3 W/m K2 has been achieved for 10BL combination. These results indicate that good quality antimony telluride, bismuth telluride and their multilayer thin films can be grown easily by using sputtering technique. It also suggests that these types of nano-structuring (multilayer structure) in these categories of materials can be promissory engineering concept for the fabrication of micro-Peltier modules.
Research Article
J. Dhanalakshmi; D. Pathinettam Padiyan
Abstract
GdxTi1-xO2 nanocomposites with x=0.00, 0.02, 0.04, 0.06, 0.08 & 0.10 were prepared through sol-gel method. The samples were characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), High resolution scanning electron microscope (HR-SEM), Raman spectroscopy and photoluminescence ...
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GdxTi1-xO2 nanocomposites with x=0.00, 0.02, 0.04, 0.06, 0.08 & 0.10 were prepared through sol-gel method. The samples were characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), High resolution scanning electron microscope (HR-SEM), Raman spectroscopy and photoluminescence spectroscopy (PL). The XRD pattern and Raman spectra confirmed the presence of crystalline nature and phase pure anatase tetragonal system. The average crystallite size of the samples was between 10 to 18 nm. HR-SEM images indicated the formation of spherical like particles of GdxTi1-xO2 nanocomposites. An obvious reduction in particle size of GdxTi1-xO2 nanocomposites were noticed while comparing the SEM images of bare TiO2 and composite samples. Coupling of Gd is responsible for slight blue shift in absorption edge. The presence of oxygen vacancies is confirmed in Raman and PL spectra. These oxygen vacancies potentially trap electrons and restrict the electron-hole recombination and thus improve the photocatalytic reactions.
Research Article
Mukta Behera; Rozalin Panda; Naresh C. Mishra; Ramakanta Naik
Abstract
In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 ...
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In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 in bulk prepared by melt quenching technique. Bi incorporation in As40Se60 with composition Bi15As40Se45 however led to nucleation of Bi2Se3 nanocrystallites in the amorphous matrix of As40Se60. The films made out of the two targets of composition As40Se60 and As40Bi15Se45 did not show any XRD peak, indicating their amorphous nature. UV-Visible-NIR spectroscopic study indicated a large decrease in the electronic band gap from 1.74 eV in films of composition As40Se60 to 1.28 eV for compositon Bi15As40Se45. This decrease is explained on the basis of a high concentration of defect states leading to the presence of localized states in the band gap due to Bi incorporation. Field emission scanning electron microscopy (FESEM) images show smooth and homogeneous surface for the As40Se60 films, while Bi incorporation led to increases of the surface roughness in the Bi15As40Se45 films. The decreased band gap and increased surface roughness on Bi incorporation in As40Se60 films indicate the suitability of these films for solar cell applications.
Research Article
Snehal L. Kadam; Pallavi M.Padwal; Sagar M.Mane; Shrinivas B.Kulkarni
Abstract
MnO2 metal oxide electrode material is synthesized by simple electrodeposition method on stainless steel substrate. The crystal structure and surface morphological characterizations of the obtained electrode are carried out by using X-ray diffraction (XRD) technique and Field Emission-Scanning Electron ...
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MnO2 metal oxide electrode material is synthesized by simple electrodeposition method on stainless steel substrate. The crystal structure and surface morphological characterizations of the obtained electrode are carried out by using X-ray diffraction (XRD) technique and Field Emission-Scanning Electron Microscopy (FE-SEM) respectively. The FE-SEM micrographs show highly porous well developed interconnected uniform nanosphere like morphology. The electrochemical properties of MnO2 electrode like Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) etc are studied in a 0.5 M Na2SO4 solution as electrolyte. The maximum specific capacitance is 543 F/g at scan rate 5 mVs-1 obtained from cyclic voltammetry (CV). The electrochemical stability of MnO2 electrode is investigated using cyclic voltammetry for 1000 cycles. The MnO2 electrode exhibits good cycling stability for 1000 cycles at scan rate100 mVs-1. The values of energy density and power density of MnO2 electrode material obtained from Galvanostatic charge-discharge studies. From all the electrochemical properties of MnO2 electrode, it indicates that it will be promising electrode material for supercapacitor application.
Research Article
Shrisha B V; Shashidhara Bhat; Parvathy Venu M; Dushyant Kushavah; K Gopalakrishna Naik
Abstract
Zinc Oxide (ZnO) nanowires (NWs) were grown on p-silicon (p-Si) substrates coated with around 10 nm thick metal films of Au, Al and Cu using vapor phase transport growth method. The effect of these metal catalysts and the substrate temperatures on the morphologies of ZnO NWs were studied using ...
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Zinc Oxide (ZnO) nanowires (NWs) were grown on p-silicon (p-Si) substrates coated with around 10 nm thick metal films of Au, Al and Cu using vapor phase transport growth method. The effect of these metal catalysts and the substrate temperatures on the morphologies of ZnO NWs were studied using field emission scanning electron microscopy (FESEM). The growth of ZnO NWs with high aspect ratio was observed at substrate temperatures above 600 oC. The structural and optical properties of the as grown ZnO NWs were characterized using X-ray diffraction (XRD) and photoluminescence spectroscopy (PL) techniques, respectively. XRD study revealed that, the grown samples possess hexagonal wurtzite structure with (002) preferential orientation. The metal droplets were observed at the tips of ZnO NWs when Au was used as catalyst, but not in the case of Al and Cu. The PL spectra exhibited two peaks, one in the UV region and the other in the visible region. The low-cost Al and Cu metal catalyst assisted growth of metal contamination-free ZnO NWs may be suitable for the device applications.
Research Article
P. Rosaiah; G. Lakshmi Sandhya; S. Suresh; Jinghui Zhu; Yejun Qiu; O. M. Hussain
Abstract
Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the ...
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Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the films prepared at lower temperatures are amorphous in nature and the films prepared at 300 oC is exhibited predominant (001) orientation with an orthorhombic crystal structure. AFM study showed that the grain size varies from 80 nm to 150 nm. The optical studies revealed that the transmittance decreased with increasing substrate temperature. The optical absorption coefficient ‘a’ determined from the experimentally measured transmittance and reflectance data for V2O5 films was found to give a better fit for the exponent n = 3/2 suggesting the direct forbidden transitions with an estimated optical band gap of 2.31 eV for the films prepared at 300 oC. The electrical conductivity has been observed to be increased from 2 x 10-6 S/cm to 3 x 10-2 S/cm by varying temperature from 30 oC to 300 oC. The electrochemical experiments exhibited the discharge capacity of about 60 μAh/(cm2-μm) for the films deposited at 300 oC.
Research Article
Shiva Sharma; Pratima Chauhan; Shahid Husain
Abstract
Mn2O3 nanoparticles have been synthesized using chemical co-precipitation method. The as synthesized nanoparticles were characterized by X-ray diffractometer (XRD), UV-Visible spectrophotometer (UV-Vis) and Fourier Transform Infra-Red (FTIR) spectrophotometer method. The results indicate that synthesized ...
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Mn2O3 nanoparticles have been synthesized using chemical co-precipitation method. The as synthesized nanoparticles were characterized by X-ray diffractometer (XRD), UV-Visible spectrophotometer (UV-Vis) and Fourier Transform Infra-Red (FTIR) spectrophotometer method. The results indicate that synthesized Mn2O3 nanoparticles possessed crystallites having sizes 12.56 nm and 11.90 nm with cubic and orthorhombic structures respectively. The two samples are named as M1 and M2. The gas response of both the samples was investigated for different concentrations of NH3 gas at room temperature. Sample M2 based thick film sensor showed enhanced sensing performance in comparison to sample M1. This is attributed to smaller crystallite size of sample M2. The sample M2 based sensor showed the response of 67.1% with the response and recovery times 65 and 71 sec respectively. The fabricated nanoparticles show promising use as room temperature NH3 sensors.
Research Article
Ashok Kumar; Rajiv Borah
Abstract
Surface modification of polymeric biomaterials for tissue engineering applications has drawn considerable research interest. In this work, the surface of polyaniline (PAni) nanofibers/chitosan nanocomposites has been modified by plasma irradiation technique to improve its biocompatibility. The average ...
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Surface modification of polymeric biomaterials for tissue engineering applications has drawn considerable research interest. In this work, the surface of polyaniline (PAni) nanofibers/chitosan nanocomposites has been modified by plasma irradiation technique to improve its biocompatibility. The average diameter of PAni nanofibers determined by HRTEM is 35.66 nm, whereas FESEM images depict interconnected network of nanofibers dispersed uniformly throughout the chitosan matrix. XRD patterns of PAni/Chitosan nanocomposites after plasma treatment indicate increase in amorphous nature. The alterations in surface morphology after plasma treatment have been confirmed with the help of SEM analysis. The surface chemistry of the samples after plasma treatment has been investigated by means of ATR-FTIR and contact angle measurements. The ATR-FTIR spectra and surface energy measurements show incorporation of polar functional groups after oxygen (O2) and nitrogen (N2) plasma treatment. Preliminary biocompatibility assessments of the plasma treated PAni/Chitosan nanocomposites have been accomplished using Alamar Blue assay with Hep G2 and Primary peripheral blood mononuclear (PBMC) cells. Both assays show maximum enhancement in cell viability for O2 and N2 plasma treated samples, comparing to the pristine one, whereas least cell viability was observed for Ar plasma treated samples. This study depicts that gas plasma treatment can effectively enhance the bioactivity of PAni/Chitosan nanocomposites and can make them attractive for tissue engineering applications. Copyright © 2016 VBRI Press.