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Nano-Tin oxide was synthesized using hydrothermal method at 150 °C for 6 h and then thin films were deposited by electrophoretic method at an optimized voltage of 100 V for 5 min on electropolished aluminum substrate. Spherical particles of about 30–50 nm diameters are observed with partial agglomeration when observed under electron microscope, which are tetragonal rutile structure. XPS results showed peaks related to Sn 4 d , Sn 3 d , O 1 s & C 1 s with spin–orbit splitting of 8.4 eV for Sn 3 d . Feasibility studies of enzyme less urea sensing characteristics of nano-tin oxide thin films are exhibited herein. The deposited films have been used for enzyme less urea sensing from 1 to 20 mM concentration in buffer solution. The sensors were characterized electrochemically to obtain cyclic voltammogram as a function of urea concentration and scan rate. The sensitivity is estimated as 18.9 μA/mM below 5 mM and 2.31 μA/mM above 5 mM with a limit of detection of 0.6 mM. [ABSTRACT FROM AUTHOR]

Abstract: This work presents glucose sensing characteristics of palladium doped tin oxide (SnO2) thin films deposited by modified plasma enhanced chemical vapor deposition (CVD) technique as a function of deposition temperature (400–600°C) and at fixed radio frequency (RF) plasma power of 150W. Stannic chloride (SnCl4) and palladium hexafluroacetyleacetonate (Pd(C5HF6O2)2) were used as precursors for tin and palladium respectively whereas oxygen (O2, 100sccm) was used as reactant gas. Granular morphology is observed with tetragonal rutile structure. Diffraction peaks related to SnO2 and Pd2Sn are observed at all the deposition temperatures. Photoelectron peaks related to Sn (3d, 3p, 4d), Pd 3d, O 1s, C 1s and N 1s were detected with varying intensities as a function of deposition temperature. Glucose oxidase (GOx) was immobilized by physical adsorption (by soaking films in 1000 units of GOx solution for three hours). The sensitivity to glucose increases with slight non-linearity from 5mg/dl to 360mg/dl and found decreasing with increasing deposition temperature. Electrochemical studies indicated rapid electron transfer kinetics and hence reversible electron transfer reactions. [Copyright &y& Elsevier]

Abstract: The work reports on the fabrication of a p–n heterojunction structure comprised of polyaniline (PANI) and TiO2 nanoparticles. PANI was deposited by plasma enhanced polymerization on TiO2 thin film substrates. The structural and the crystalline properties demonstrated the coherence and the substantive interaction of the plasma polymerized PANI molecules with the TiO2 nanoparticle thin film. The UV–Vis studies of PANI/TiO2 thin film supported the internalization of PANI with TiO2 nanoparticles due to transition of the phenyl rings with the lone pair electrons () of the nitrogen atom present in the PANI molecules. The – characteristics of the PANI/TiO2 heterojunction structure were obtained in the forward and the reverse biased at applied voltage ranging from −1 V to +1 V with a scan rate of 2 mV/s. The proficient current in the PANI/TiO2 heterojunction structure was attributed to the well penetration of PANI molecules into the pores of the TiO2 nanoparticle thin film. The – characteristics ensured an efficient charge movement at the junction of PANI/TiO2 interface and thus, behaved as a typical ohmic system. [Copyright &y& Elsevier]

Abstract: Urea sensing properties of zinc oxide in thick film form are presented here. Zinc oxide thick films were prepared on Al-sheet by conventional doctor blade method using organic additives. Flower-like structure and nanobelts of ZnO was synthesized by solution method using zinc acetate dihydrate and sodium hydroxide. Structural morphology significantly changed with precursor concentration (0.3–0.5M) from a belt to flower-like structure. Urease was covalently attached with zinc oxide (by soaking in urease solution containing 100 units for 3h). In general, conductivity of film increases after urease immobilization. The urease immobilized films were found sensitive to urea concentration from 1mM to 100mM. Three different sensitivity regions are observed viz. (i) lower concentrations (below 10mM); (ii) linear region up to 50mM; and (iii) a saturation region above 50mM. Sensors are extremely sensitive in region (i). Nanobelt structure of ZnO resulted in highest urea sensitivity. Sensors exhibited linear response when tested for different concentration of human urine in buffer solution (1:9 to 4:6). The sensor responses are reproducible, reliable, reversible and selective, with a response time of 6s. [Copyright &y& Elsevier]

Abstract: In this paper we present a systematic study on the morphological variation of ZnO nanostructure by varying the pH of precursor solution via solution method. Zinc acetate dihydrate and sodium hydroxide were used as a precursor, which was refluxed at 90°C for an hour. The pH of the precursor solution (zinc acetate di hydrate) was increased from 6 to 12 by the controlled addition of sodium hydroxide (NaOH). Morphology of ZnO nanorods markedly varies from sheet-like (at pH 6) to rod-like structure of zinc oxide (pH 10–12). Diffraction patterns match well with standard ZnO at all pH values. Crystallinity and nanostructures were confirmed by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) pattern, which indicates structure grew along [0001] direction with an ideal lattice fringes distance 0.52nm. FTIR spectroscopic measurement showed a standard peak of zinc oxide at 464cm−1. Amount of H+ and OH− ions are found key to the structure control of studied material, as discussed in the growth mechanism. [Copyright &y& Elsevier]

Abstract: Rosette-like structures of ZnO were synthesized at low temperature (60°C) using solution process over 20min of time. Hydroxylamine hydrochloride was used as capping agent with zinc nitrate hexahydrate and sodium hydroxide. Transition from triangular shaped plate like particles to rosette-like structure and to individual nanorods is observed with increasing refluxing temperature. Single-crystalline nature with wurtzite hexagonal phase is confirmed from transmission electron microscopic observations. Photoelectron spectroscopic measurement presented spectra close to the standard bulk ZnO, with an O 1s peak composed of surface adsorbed O–H group, O2− in the oxygen vacancies on ZnO structure and ZnO. [Copyright &y& Elsevier]

Abstract: Here we present a preliminary study on the interaction of bio-molecules (deoxyribonucleic acid (DNA) and nano-hydroxyapatite (HA)) with multi-wall carbon nanotubes (MWCNTs). Initially, nano-size hydroxyapatite was interacted with functionalized carbon nanotubes (FCNTs, HFCNTs) and then 100 base pair (bp) DNA was immobilized (DHFCNTs). Well-known acid treatment was used to functionalize the MWCNTs. The characteristic vibrational and stretching modes of hydroxyl and carbonyl group were observed at 3401, 1632 and 1708cm−1, validating fucntionalization. The existence of 31P and 1H signals were measured by the solid state NMR spectroscopy for HA, HFCNTs and DHFCNTs which revealed the chemical interaction between HA powder and FCNTs. Appearance of an N 1s peak in the photoelectron spectra indicated the covalent attachment. Band deterioration is observed from slab gel-electrophoresis studies. Electrophoretic time study indicated that 20min is required to run the DNA in column. [Copyright &y& Elsevier]

Abstract: Faceted nanoparticles of zinc oxide were successfully achieved via thermal annealing of hydrozincite (Zn5(CO3)2(OH)6) powder at different annealing temperatures, i.e. 300, 500 700 and 900°C in air for 2h using sol–gel method by refluxing for 6h at 70°C. Zinc acetate dihydrate (Zn(CH3COO)2·2H2O) was used as precursor with urea (NH2CONH2) for the synthesis of hydrozincite. The morphological observations by field emission scanning electron microscope indicated increase in particle size from 20 to 300nm with increase in the annealing temperatures. High resolution TEM and SAED measurement indicate the distance between two lattice fringes is ∼0.52nm corresponding to (0001) fringes. A standard peak of zinc oxide was observed at 457cm−1 from the FTIR analysis. Thermo gravimetric analysis (TGA) revealed that the primary weight loss starts at ∼130°C due to solvent evaporation and the secondary weight loss due to phase transition from hydrated zinc oxide to zinc oxide was observed at ∼290°C. [Copyright &y& Elsevier]

Abstract: A feasibility study of glucose oxidase (GOx) immobilized tin oxide thin films, consisting of nano-baskets, for glucose sensing is presented. The nano-baskets of SnO2 were grown on in-house fabricated anodized aluminum oxide pores of ∼80-nm diameter using plasma enhanced chemical vapor deposition (PECVD) at an RF power of 60W. Hydrated stannic chloride was used as a precursor and O2 (20sccm) as a reactant gas. The deposition was carried out from 350 to 450°C at a pressure of 0.2Torr for 15min each. Deposition at 450°C resulted in crystalline film with basket-like (nano-sized) structure. GOx was immobilized by physical adsorption (soaking films in GOx solution containing 1000 units for 3h). Increase in film conductivity was noticed after GOx immobilization. The immobilized films were found sensitive to glucose (C2H12O6, dextrose) concentration from 10 to 360mg/dl. Sensitivity increases linearly with glucose concentration. Nano-baskets resulted in higher sensitivity in comparison with other structures. From the elemental analyses of the films after GOx immobilization, GOx was found covalently attached with tin oxide, as evident by N 1s peak in the photoelectron spectra. A possible sensing mechanism is presented and discussed. [Copyright &y& Elsevier]

Abstract: Urea sensing properties of tin oxide thin films are presented here. Tin oxide thin films were deposited by modified plasma enhanced chemical vapor deposition (CVD) technique at the deposition temperatures of 500–800°C and RF power of 100W. Film morphology significantly changed with deposition temperature from flakes to tiny crystals having tetragonal rutile structure grown along the [110] direction. Urease was covalently attached with tin oxide (by soaking in urease solution for 3h). In general, conductivity of film increases after urease immobilization. The urease immobilized films were found sensitive to urea concentration from 1 to 100mM. Three different sensitivity regions are observed viz. (i) lower concentrations (below 10mM); (ii) linear region up to 50mM and (iii) a saturation region above 50mM. Sensors are extremely sensitive in region (i). Films deposited at higher temperature resulted in increased urea sensitivity. From the elemental analyses of the films after urease immobilization, urease was found attached with tin oxide, as evident by N 1s peak in the photoelectron spectra. A possible sensing mechanism is presented and discussed. [Copyright &y& Elsevier]

Abstract: Effect of the structure-directing agent on the floral (depicting flower) morphological variation of ZnO is systematically studied and presented here. Flowery decorated (resembling flower) zinc oxide structure composed of hexagonal nanorods (sharp tips and wider bases) was synthesized at 90°C using zinc acetate dihydrate and sodium hydroxide at various concentrations of hydroxylamine hydrochloride for 12h by solution method. Single crystalline nature with the wurtzite hexagonal phase remained unaltered with increasing concentration of hydroxylamine hydrochloride while the morphology changes from nanorod to plate like structure. Photoelectron spectroscopic measurement presented spectra close to the standard bulk ZnO, with an O 1s peak composed of surface adsorbed OO2− in the oxygen vacancies on ZnO structure and ZnO. At higher concentration (0.8M), surface adsorbed Oncreases while other component decreases because of the changes in the nucleation and surface energy. Results clearly indicate that hydroxylamine hydrochloride works as a structure-directing agent without affecting other properties. [Copyright &y& Elsevier]

Abstract: Synthesis of flower-shaped ZnO nanostructures composed of hexagonal ZnO nanorods was achieved by the solution process using zinc acetate dihydrate and sodium hydroxide at very low temperature of 90°C in 30min. The individual nanorods are of hexagonal shape with sharp tip, and base diameter of about 300–350nm. Detailed structural characterizations demonstrate that the synthesized products are single crystalline with the wurtzite hexagonal phase, grown along the [0001] direction. The IR spectrum shows the standard peak of zinc oxide at 523cm−1. Raman scattering exhibits a sharp and strong E2 mode at 437cm−1 which further confirms the good crystallinity and wurtzite hexagonal phase of the grown nanostructures. The photoelectron spectroscopic measurement shows the presence of Zn, O, C, zinc acetate and Na. The binding energy ca. 1021.2eV (Zn 2p3/2) and 1044.3eV (Zn 2p1/2), are found very close to the standard bulk ZnO binding energy values. The O 1s peak is found centered at 531.4eV with a shoulder at 529.8eV. Room-temperature photoluminescence (PL) demonstrate a strong and dominated peak at 381nm with a suppressed and broad green emission at 515nm, suggests that the flower-shaped ZnO nanostructures have good optical properties with very less structural defects. [Copyright &y& Elsevier]

Abstract: Single crystalline needle-shaped zinc oxide nanorods were synthesized via sonochemical methods using zinc acetate dihydrate and sodium hydroxide at room temperature. Morphological investigation revealed that the nanoneedles are of hexagonal surfaces along the length. The typical diameter and length vary from 120 to 160nm and 3 to 5μm, respectively. Sonication time appears to be a critical parameter for the shape determination. Detailed structural characterization confirmed that the nanorods are single crystalline with wurtzite hexagonal phase. A standard peak of zinc oxide was observed at 520cm−1 from the Fourier transform infrared spectroscopy. The ultra-violet visible and room temperature photoluminescence (PL) spectroscopic results demonstrate that the synthesized material has good optical properties. [Copyright &y& Elsevier]

Abstract: Hydrothermal growth of hexagonal ZnO nanorods on the annealed titanate nanotube films is reported as a function of molar ratio of Zn(NO3)2 and methenamine (1:1–1:4). The molar ratio of 1:4 results in a dense and thinner rod in comparison with other molar ratios. Corn-like structures of the rods are believed to be due to the higher amine concentration. Raman peaks at 437 and 331cm−1 are assigned to E2 and E2H–E2L modes. Near band gap edge and green photoluminescence emission indicates the structural and oxygen vacancy. O 1s peak is found built-up of sub-peaks at 530.62, 531.8 and 532.84eV corresponding to O2− on normal wurtzite structure and OH and oxygen vacancies of ZnO, respectively. [Copyright &y& Elsevier]

Abstract: The nanobaskets of SnO2 were grown on in-house fabricated anodized aluminum oxide pores of 80nm diameter using plasma enhanced chemical vapor deposition at an RF power of 60W. Hydrated stannic chloride was used as a precursor and O2 (20sccm) as a reactant gas. The deposition was carried out from 350 to 500°C at a pressure of 0.2Torr for 15min each. Deposition at 450°C results in highly crystalline film with basket like (nanosized) structure. Further increase in the growth temperature (500°C) results in the deterioration of the basket like structure and collapse of the alumina pores. The grown film is of tetragonal rutile structure grown along the [110] direction. The change in the film composition and bonded states with growth temperature was evident by the changes in the photoelectron peak intensities of the various constituents. In case of the film grown at 450°C, Sn 3d5/2 is found built up of Sn4+ and O–Sn4+ and the peaks corresponding to Sn2+ and O–Sn2+ were not detected. [Copyright &y& Elsevier]

Abstract: Diamond thin films have been deposited using hot filament chemical vapour deposition technique on manually scratched p-Si(100) substrate, with and without magnesium interlayer. In spite of magnesium melting point being lower (T m =649°C) than the growth temperature of the substrate (T s ∼750°C) used in these experiments, it was found that high quality diamond films could be grown on Mg covered substrate. A liquid substrate is probably generated during the diamond film growth. Raman spectroscopy analysis exhibited only the triply degenerate, zone centre optical phonon peak at 1333cm−1 indicating that nearly stress free crystallites were present. Broadening of the Raman peak (∼11.76cm−1) indicates that some small crystallites also are present. Scanning electron and atomic force microscopy accompanied by X-ray diffraction analysis where used to compare the details of diamond film growth directly on scratched Si(100) and Mg interlayered scratched Si(100) substrates. [Copyright &y& Elsevier]

Abstract: Gas-phase diagnostics in the catalytic chemical vapor deposition processes of the SiH4/NH3/H2 system were carried out to examine the effect of H2 dilution. The decomposition efficiency of NH3 showed a sharp decrease with the introduction of a small amount of SiH4, but this decrease was recovered by the addition of H2 when the NH3 pressure was low. On the other hand, at higher NH3 pressures, the decomposition efficiency showed a minor dependence on the H2 partial pressure. The addition of SiH4 to the NH3 system decreases the H-atom density by one order of magnitude, but this decrease is also recovered by H2 addition. H atoms produced from H2 must re-activate the catalyzer surfaces poisoned by SiH4 when the NH3 pressure is low. [Copyright &y& Elsevier]

Abstract: Diamond films were grown, under identical conditions on scratched Si (100) with and without MgO interlayers by using hot filament chemical vapour deposition. Initially both kinds of the substrates were biased for 30 min at 750±50 °C to enhance the nucleation density. A 1:100 vol.% mixture of CH4 and H2 gases was used for deposition at a total pressure of ∼4×103 Pa. Deposition was carried out for total of 2 h and the analysis of the films was carried out using Scanning Electron Microscopy, Atomic Force Microscopy, X-ray Diffraction and Raman Spectroscopy. Both substrates showed predominantly (111) oriented crystals of diamond but with different surface morphology. The crystallites on scratched Si (100) surface are in general (∼1.5–2 μm) and those on MgO overlayer are smaller (<1 μm), but denser film occurs with MgO overlayer on Si (100) substrate. [Copyright &y& Elsevier]

A study on the effect of growth kinetics and properties of diamond film obtained by addition of argon (∼7 vol%) into the methane/hydrogen mixture is carried out using a hot-filament chemical vapor deposition system. A negative bias was used as a nucleation enhancement method in addition to the argon dilution. The scanning electron microscopic images show well faceted crystallites with a predominance of angular shapes, corresponding to 〈1 0 0〉 and 〈1 1 0〉 crystalline surfaces. The surface nucleation density and growth rate with argon dilution is found to be two orders of magnitude higher than those without argon dilution. The micro-Raman spectra show a good-quality film whereas X-ray photoelectron spectra show existence of only carbon phase (C1s peak). The effect of argon dilution on the microstructure of the diamond is discussed in the view of reported literature. [Copyright &y& Elsevier]

MoO3-doped SnO2 nano-particles were prepared using sol–gel method with 0.1 molar solutions of SnCl4·5H2O and MoO3 with different doping concentration from 5.03×10−4 to 5.04×10−3 mol. The average grain size varies from 12 to 80 nm obtained by varying calcination temperature from 300 to 900 °C. Thick film samples, of about 25 μm thickness, were tested for CO and H2 in the concentration range of 15–1000 ppm in ambient air. The samples exhibit selective response to CO and H2 at 140 and 240 °C, respectively. The sensitivity increases with doping concentration for H2, whereas, for CO, it increases rapidly till the doping concentration of 2.01×10−3 mol and then reaches to saturation. The observed maximum sensitivity factor for CO at 2.01×10−3 mol doping is ∼30, whereas for H2, it is ∼10 at 5.04×10−3 mol doping. The response and recovery time is ∼5 and 10 s respectively. [Copyright &y& Elsevier]

Abstract: The catalytic decomposition conditions of O2, N2O and NO were investigated to avoid oxidization of heated tungsten filaments. It was confirmed that no oxidization takes place in the presence of an excess amount of H2 or NH3: for example, when the catalyzer temperature is 1990 K and the H2/O2 flow rate ratio is more than 18. These results are consistent with the recent results that no oxidization is observed in the SiH4/NH3/H2/O2/He system to deposit SiO x N y films as long as the O2 flow rate is low. In addition, it was revealed that in this SiH4/NH3/H2/O2/He system, O2 is not only decomposed on the catalyzer surfaces but also is consumed in homogeneous and/or heterogeneous reactions. One of the consumption paths in the gas phase should be the reaction with SiH3 to produce SiO. [Copyright &y& Elsevier]

We report the solution-based synthesis and material characterization of the Cd substituted hybrid organic-inorganic lead halide perovskite CH 3 NH 3 Pb 1-x Cd x I 3 (x = 0.0, 0.03, 0.05, 0.08). Structure and morphology of the samples were investigated using XRD, FESEM and HRTEM techniques. XRD results confirmed a tetragonal perovskite structure (I4/ mcm) through the doping range. Optical absorption, band gap and bonding character were studied by UV–visible, FTIR and photoluminescence spectroscopy. Oxidation states, binding energy and chemical composition were determined by XPS and EDAX. A low value of Urbach energy (~14 meV) indicated high sample quality with low defects and trap states. The undoped samples had a direct energy gap of 1.56 eV, which reduced to 1.50 eV upon Cd doping. Most significantly, the absorption coefficient of CH 3 NH 3 Pb 1-x Cd x I 3 remained high (~103) above 750 nm in the spectrally important infrared range as compared to CH 3 NH 3 PbI 3 , which approached zero. The enhanced structural and optical properties upon Cd doping make these materials promising photo absorber candidates compared to undoped CH 3 NH 3 PbI 3. • Cd-doped perovskite CH 3 NH 3 Pb 1-x Cd x I 3 synthesized via a single step solution process. • Nanocrystalline tetragonal structure with low defects was preserved on Cd doping. • Cd doped samples exhibited a slight reduction in the optical energy gap. • Cd doping led to greatly enhanced absorption in the infra-red region above 750 nm. [ABSTRACT FROM AUTHOR]

The development of energy storage materials with high capacity and rapid charging and discharging ability have become the most important and major issues of concern in recent years. In this study, a mesoporous nickel sulfide (NiS) hierarchical framework was synthesized using a simple solvothermal method under optimized experimental conditions, including the amount of sulfur and experimental time, and characterized using a range of spectroscopic and microscopic techniques. The resulting materials were tested further as electrode materials in an electrochemical half-cell assembly and full cell solid-state symmetric assembly cell. The optimized mesoporous nickel sulfide hierarchical showed excellent specific capacitance performance with outstanding cycling stability (∼88.57%) after 5000 consecutive charge discharge cycles. A prototype symmetric supercapacitor device was also assembled using hierarchical flower-like NiS and the measured device performance showed a high capacitance of 11.15 F/g, high energy density of 0.991 Wh/kg at a power density of 132 W/kg, and at power density of 261.11 W/kg at an energy density of 0.329 Wh/kg, and excellent cycling stability (83.8% with 92.9% coulombic efficiency after 2000 cycles at 0.26 A/g). The potential applications of the above device were demonstrated by powering a light emitting diode and commercially available fan for more than 30s discharging time. [ABSTRACT FROM AUTHOR]

The development of electrically conductive metal sulfide-based polymer nanocomposites for energy storage materials has been a major focus by researchers to solve the energy crisis. In this study, a simple and facile method was used to construct a nanocomposite by combining a mechanically exfoliated MoS 2 (M-MoS 2 ) sheet with polyaniline (Pani) using a simple and scalable in-situ chemical oxidative polymerization method. The as-prepared nanocomposite (M-MoS 2 -Pani nanocomposite) was characterized further by usual basic spectroscopic techniques, such as X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The electrochemical supercapacitive characteristics of the M-MoS 2 -Pani nanocomposite was tested in a three-electrode assembly by obtaining cyclic voltammetric (CV) curves and galvanostatic charge-discharge (GCD) measurements. The results were compared with those of a C-MoS 2 -Pani nanocomposite that had been synthesized using bulk MoS 2 . The M-MoS 2 -Pani nanocomposite synthesized using exfoliated MoS 2 exhibited a higher specific capacitance of 510.12 F g −1 at a current of 1 A g −1 than the C-MoS 2 -Pani nanocomposite (225.15 F g −1 ), which was synthesized using bulk C-MoS 2 delivered. The enhanced electrochemical supercapacitive performance was correlated to the synergistic effect and chemical interactions between the Pani and MoS 2 , which provide high electrical conductivity and a sufficient empty state for electrode/electrolyte contact. [ABSTRACT FROM AUTHOR]

Yttrium Ferrite nanoparticles were prepared by citrate precursor method at reasonably low temperature. Morphological and elemental studies reveal the formation of monophasic orthorhombic YFeO 3 nanoparticles with fairly uniform distribution of nearly spherical particles, high specific surface area of ~ 338 m 2 /g and visible band gap of 2.5 eV. The electrical properties (i.e. dielectric and conductivity) were estimated from ac spectroscopic data as a function of temperature. The wasp-waisted shaped hysteresis loop displayed low H c of 280 Oe, M s of 2.0 emug − 1 and M r of 0.45 emug − 1 indicating canted antiferromagnetism with weak ferromagnetic behaviour. In addition to ferromagnetism, a room temperature ferroelectric loop confirmed the multiferroic behaviour of the materials. The humidity sensing properties were investigated from 8 to 80% of RH (Relative Humidity) that showed a linear response with a sensitivity of 16 nF/RH% at room temperature. Dye sensitized solar cell (DSSC) was constructed in combination with TiO 2 powder to determine the photo-conversion efficiency, current density and open circuit voltage. Photocatalytic generation of hydrogen by using YFeO 3 nanoparticles has also been studied under the visible light irradiations which showed a significant H 2 evolution reaction rate up to 131.6 μmol h − 1 g − 1 . [ABSTRACT FROM AUTHOR]

Abstract: A p–n heterostructure diode of polyaniline (PANI) and ZnO nanoparticles was prepared by the electrophoretic deposition of PANI on ZnO nanoparticles thin film coated fluorine doped tin oxide (FTO) glass at room temperature. The morphological, structural and optical studies substantiated the penetration, bonding and the interaction of PANI molecules with ZnO nanoparticles thin film substrates. The prominent blue shift in UV-Vis spectra indicated the strong interaction between ZnO and PANI through the decreased degree of orbital overlap between electrons of the phenyl rings with the lone pair of the nitrogen atom in the PANI molecules. The characteristics of PANI/ZnO heterostructure diode showed weak rectifying behavior with non-linear nature of curve of PANI/ZnO heterostructure device. The typical ohmic behavior was observed by the characterization of PANI/ZnO heterostructure at the interface of PANI and ZnO thin film layer without top Pt thin layer contact. [Copyright &y& Elsevier]

Abstract: A conversion from commercial titania (TiO2) nanoparticles to nanotubes was achieved by hydrothermal method with 10M NaOH solution at various reaction temperatures ranging from 70 to 150°C over 48h. Most of intercalated sodium in as-synthesized titanate nanotubes was removed by washing with 0.1M HCl solution for 1h. The samples were then dried at room temperature and annealed at 300, 400, 500, and 600°C in air for 1h. With increasing reaction temperature, the morphology varied from spherical particles to two-dimensional nano-sheets to one-dimensional nanotubes. At 110°C, nanosheets transformed to tube-like structure. The reaction temperature is a key factor in determining the overall aspect ratio of the tubular material. X-ray diffraction supports the structural transformation indicating the gradual changes in the phase and crystallinity of the synthesized powder. Tubular structure collapsed when annealed at 600°C and converted to anatase phase totally. O 1s peak is found built-up of sub-peaks of H2O, –OH, Ti–O. Annealing at 600°C reduces the peak intensity of H2O (531.01eV) and –OH, while that of Ti–O increases. It is found that annealing removes the chemical bonds such as H2O, –OH from the titanate are also converts the bonded states of titanate to that of titania. [Copyright &y& Elsevier]

Abstract: Immobilization of avidin was carried out by functionalizing the multi-wall carbon nanotubes (MWCNTs). Treatment with nitric acid and sulfuric acid mixture (1:3, optimized ratio) leads to the functionalization of nanotubes as observed from Fourier transform infrared absorption spectroscopy (FTIR) measurements. Avidin was coupled with the solution of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylamino propyl)-carbodiimide hydrochloride (EDC) and then immobilized on nanotubes. X-ray photoelectron spectroscopic (XPS) studies show a shift in the peak position of C 1s towards lower energy side and changes in the bands with treatment/immobilization. The shoulders and shift in photoelectron peak positions indicate the destruction of the graphite structure of the surface layer. SEM images showed that after functionalization, the nanotubes are seen with open ends, granular surface and are joined together. This indicates that after treatment, the CNTs reactivity increased at the ends as well as at the sidewalls. It is believed that the NHS often assist the carbodiimide coupling in the presence of EDC, reacts with the amine function to yield the amide bond. The carbodiimide catalyzes the formation of amide bonds between carboxylic acids and amines by activating carboxyl. The reaction of complex containing avidin can form a covalent bond with functionalized carbon nanotubes as observed from FTIR and XPS measurements. [Copyright &y& Elsevier]

A systematic study of the growth of indium tin oxide (ITO) thin films on polyethylene terephthalate substrate was carried out using RF reactive magnetron sputtering. The effect of oxygen admixture to sputtering gas, sputtering pressure (4.5×10−1 to 6.8×10−1 Pa), RF power (30–50 W) and growth time (15–50 min) on the electrical and optical properties of ITO thin films was investigated. An indium tin alloy (90:10) of 99.999% purity was used as target. Deposition was carried out at room temperature. Cracks in the films were not observed. It is found that the increase in admixture of O2 to Ar sputtering gas decreases the growth rate. A minimum value of resistivity (7×10−3 Ω cm), decreases in the mobility, reduction in particle size, an average transmittance of ∼80% in UV–Vis range with carrier concentration of ∼5.9×1019 atmos/cm3 and mobility of ∼37 cm2/V s was found with increasing O2 admixture. The increase in sputtering pressure has less effect on growth rate, changes the distribution of particles with increase in their sizes, little variation in Sn/In ratio and a minimum resistivity of 1.9×10−3 Ω cm. The increasing pressure results in improved transmittance to above 80%. Increase in RF power results in a minimum resistivity of 1.9×10−3 Ω cm (at 50 W) and decreases the carrier mobility to 3.5 cm2/V s. A linear increase in the film thickness with increase in optical transmittance to ∼85 is found with increasing growth time. It can be concluded that the film grown at 10% of O2 admixture, 5.6×10−1 Pa sputtering pressure and RF power of 50 W, can meet the requirement of a good transparent and conducting ITO film on polymer substrate. [Copyright &y& Elsevier]

Indium tin oxide (ITO) thin films were deposited on Si(100) substrates using plasma enhanced chemical vapor deposition technique. The metal-organic sources used in this study were Tris (2,2,6,6-tetramethyl-3,5-heptanedionato) indium(III) and tin(III) acetate of 99.9% purity, which are readily available. The deposition of ITO films was carried out for 1 h at different reaction temperatures (200, 250, 300 and 350 °C), with oxygen as reaction gas (20 sccm) and argon as carrier gas (200 sccm). The deposited films were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The minimum sheet resistance, measured using a four-probe method, was 2500 Ωcm−2 at a deposition temperature of 300 °C. XRD analysis shows a structural change and a highly textured film with 〈100〉 preferred orientation with increasing deposition temperature. Growth rate, estimated from SEM images of the deposited film was ∼1010 cm−2 h−1. It was observed from XPS results that oxygen atoms were bonded to In and Sn atoms indicating formation of ITO compound (bonded states of In2O3). It is also seen that all the examined ITO film contains amorphous and crystalline phases. [Copyright &y& Elsevier]

To get insight into the thermal management of twisted bilayer graphene based devices, the interpretation of temperature variation on twisting properties becomes crucial. In this aspect, we report the temperature dependent Raman scattering of twisted bilayer graphene (tBLG) on the Si substrate having SiO 2 thickness 300 nm. The tBLG samples have been directly grown on the copper foil substrate using a home-built low pressure chemical vapor deposition (LPCVD) setup. The temperature dependent Raman scattering has been studied on two samples of tBLG named as tB 1 and tB 2. The twisting nature of bilayer graphene film has been analyzed using R, G, and 2D peak characteristics in Raman spectra. The Raman mapping with respect to different peak parameters of G and 2D peak (intensity, width, and position), intensity ratio (I 2D /I G) has been employed to probe the uniformity of tBLG film. In tB 1 , the R peak has been found at 1395.82 cm−1 and not observed in sample tB 2 at room temperature. The temperature dependence of G and 2D peak frequency in Raman spectra has been investigated in the temperature range from 80 to 450 K. In tB 1 and tB 2 , the temperature coefficient of G peak has been found to be - (0.97 ± 0.34) × 10−2 cm−1/K, and - (1.08 ± 0.15) × 10−2 cm−1/K, respectively. Further, the extracted value of temperature coefficient of 2D peak in tB 1 , and tB 2 are - (2.92 ± 0.80) × 10−2 cm−1/K, and - (3.01 ± 0.29) × 10−2 cm−1/K respectively. Additionally, the twist angle has been estimated as ∼23°-27° for T ≤ 300 K and 3°-8° for T > 300 K in tB 1. In tB 2 , it has been found to be ∼13°-16° for the temperature range of 80–200 K and 5°-9° for 250–450 K. These findings shed light on the twisting behavior of bilayer graphene film and its anharmonic properties. [Display omitted] • The tBLG samples are directly grown on the copper foil substrate using a home-built LPCVD setup. • The twisting nature of bilayer graphene film are analyzed using R, G, and 2D peak characteristics in Raman spectra. • The Raman mapping of G and 2D peak parameters are employed to probe the uniformity of tBLG film. • The peak frequency of G and 2D in Raman spectra are investigated in the temperature range from 80 to 450 K. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate synthesis and application of two-dimensional (2D) rectangular ytterbium oxide (Yb 2 O 3 ) nanodisks via a facile hydrothermal method. The structural, morphological, compositional, crystallinity, and phase properties of as-synthesized nanodisks were carried out using several analytical techniques that showed well defined 2D rectangular nanodisks/sheet like morphologies. The average thickness and edge length of the nanosheet structures were 20 ± 5 nm and 600 ± 50 nm, respectively. To develop urea biosensor, glassy carbon electrodes (GCE) were modified with Yb 2 O 3 nanodisks, followed by urease immobilization and Nafion membrane covering (GCE/Yb 2 O 3 /Urease/Nafion). The fabricated biosensor showed sensitivity of 124.84 μA mM −1 cm −2 , wide linear range of 0.05–19 mM, detection limit down to ~ 2 μM, and fast response time of ~ 3 s. The developed biosensor was also used for the urea detection in water samples through spike-recovery experiments, which illustrates satisfactory recoveries. In addition, the obtained desirable selectivity towards specific interfering species, long-term stability, reproducibility, and repeatability further confirm the potency of as-fabricated urea biosensor. [ABSTRACT FROM AUTHOR]

Brucellosis is endemic worldwide due to the nomadic heritage of drinking fresh milk from goats, sheeps and camels. This study aims at developing an antibody based sensor for the detection of Brucella , wherein the binding of Brucella to the sensor will be detected by measuring the changes in electrical signals via cyclic voltammetric properties. The morphology of the used MWCNTs was observed under SEM, FESEM, and TEM. The MWCNTs (ropes like structure) used for the development of sensor were 2–4 μm in length and ∼10–15 nm in diameter as observed under SEM, FESEM, and TEM. MWCNTs were functionalized via acid treatment/oxidation process and the functional behavior of molecules was confirmed with FTIR spectroscopy. Antibodies were conjugated onto the functionalized MWCNTs using classical EDC coupling reactions. When observed under SEM, binding of Brucella abortus to these anti- Brucella antibody functionalized MWCNTs was clearly observed. Finally, these antibody functionalized MWCNTs were deposited on aluminum sheets for the voltammetric detection of Brucella . Results indicate that the antibody functionalized MWCNTs prepared in this study can be used successfully for the detection of Brucella . [ABSTRACT FROM AUTHOR]

Nanostructured magnesium oxide (size<10nm) grafted carboxyl (COOH) functionalized multi-walled carbon nanotubes (nMgO–cMWCNTs) deposited electrophoretically onto indium tin oxide (ITO) coated glass electrode and have been utilized for Vibrio cholerae detection. Aminated 23 bases single stranded DNA (NH2–ssDNA) probe sequence (O1 gene) of V. cholerae has been covalently functionalized onto nMgO–cMWCNTs/ITO electrode surface using EDC-NHS chemistry. This DNA functionalized MgO grafted cMWCNTs electrode has been characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques. The results of XPS studies reveal that sufficient O–CåO groups present at the nMgO–cMWCNTs surface are utilized for DNA binding. The results of hybridization studies conducted with fragmented target DNA (ftDNA) of V. cholerae using electrochemical impedance spectroscopy (EIS) reveal sensitivity as 3.87Ωng−1 cm−2, detection limit of ∼21.70ngµL−1 in the linear range of 100–500ngµL−1 and stability of about 120 days. The proposed DNA functionalized nMgO–cMWCNTs nanomatrix provides a novel impedimetric platform for the fabrication of a compact genosensor device for biomedical application. [ABSTRACT FROM AUTHOR]

Abstract: A novel organic–inorganic platform comprising of chitosan (CH) modified nanostructured magnesium oxide (nanoMgO) has been electrophoretically deposited on the indium-tin-oxide (ITO) substrate. The single stranded probe DNA (ssDNA) sequence of Vibrio cholerae has been covalently functionalized onto CH-nanoMgO/ITO surface. The cytotoxicity assay of nanoMgO particles, examined using human intestinal cell line (INT 407), reveals no significant cytotoxicity at the given doses in the range of 50–350μg/mL. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and various microscopic techniques have been employed for the structural and morphological analysis of the fabricated electrodes. The electrochemical response studies of ssDNA and fragmented genomic DNA hybridized electrode (dsGDNA/CH-nanoMgO/ITO) have been carried out using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The dsGDNA/CH-nanoMgO/ITO bioelectrode exhibits a linear response in the range 100–500ng/μL with improved sensitivity of 36.72nA/ng/cm2, faster response time of 3s and high stability of 3–4 months under refrigerated condition. The lower detection limit of fabricated genosensor has been estimated as 35.20ng/μL and it shows good reproducibility/repeatability. [Copyright &y& Elsevier]

Abstract: Copper electrochemical deposition on titanium with a ruthenium seed layer was investigated. The chemicals for the acid-bath ruthenium electrochemical deposition were ruthenium(III) chloride hydrate (RuCl3·3H2O), hydrochloric acid (HCl), sulfamic acid (NH2SO3H), and polyethylene glycol. The chemicals for the acid-bath copper electrochemical depositions were copper(II) sulfate hydrate (CuSO4·5H2O), sulfuric acid (H2SO4), and polyethylene glycol. Results were analyzed by field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS). Ruthenium thin film of ∼30nm thickness, with equiaxial grains <10nm, was deposited, on a blanket Ti with a root mean square roughness of 8.3nm, at 2V for 90s. XPS and RBS analyses showed the presence of metallic Ru. The Ti substrate was found stable with respect to ECD of Ru but the Ru/Ti bilayer was not found stable in the Cu acid bath, resulting in the diffusion of Ti into Ru film. The depth profiling studies indicates that Ru film thickness ca. 1.4nm and deposition time of 10s can act as a good seed layer. [Copyright &y& Elsevier]

Indium tin oxide (ITO) thin films were deposited on Si(100) substrates using plasma enhanced metallorganic chemical vapor deposition (PEMOCVD). Precursors used in this study were tris (2,2,6,6-tetramethyl-3,5-heptanedionato) indium(III) and tin(III) acetate of 99.9% purity, which are readily available. The precursors decompose at very low temperatures, giving flexibility to use low temperature substrates. The deposition of ITO films was carried out at different oxygen flow rates (5–20 sccm) and Argon flow rate of 200 sccm. R.F. power and reaction temperature was fixed at 150 W and 300 °C, respectively. The deposited films were analyzed using X-ray diffraction, scanning electron microscopy, α-step profilometer and X-ray photoelectronic spectroscopy (XPS). Sheet resistance of ITO film was measured using four-probe method. XRD analysis shows that grains are aligned in (222) and (400) direction and changes from (222) to (400) direction with the increasing oxygen flow rate. SEM results shows that the size of grains decreases as the oxygen flow rate increases with a slight increase in size at 20 sccm. The thickness of the films is ∼7500 A˚ in all the cases. Sheet resistance of ITO film decreases with increasing oxygen flow rate up to 15 sccm and a little increase in sheet resistance at 20 sccm. XPS results manifested that oxygen atoms are bonded to In and Sn atoms indicating the formation of ITO compound. [Copyright &y& Elsevier]