Faculty Publications
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Item Chemical free synthesis of graphene oxide in the preparation of reduced graphene oxide-zinc oxide nanocomposite with improved photocatalytic properties(Elsevier B.V., 2018) Meti, S.; Rahman, M.R.; Ahmad, M.I.; Bhat, K.U.In the present investigation, the reduced graphene oxide – zinc oxide (rGO-ZnO) was prepared by rapid microwave-assisted hydrothermal technique. The chemical free graphene oxide (GO), synthesized by Tang Lau technique, was used in the preparation of rGO-ZnO nanocomposite. The GO gets reduced to rGO during microwave irradiation and provides the necessary nucleation site for the ZnO nanorods to grow in [0 0 0 1] direction. These ZnO nanorods were completely wrapped with rGO sheets, confirmed by the synchrotron XRD and TEM techniques. The phases and cell parameters were calculated by Rietveld method. The prepared composite was used for the photodegradation of methyl orange (MO) dye from water under UV light. Investigation revealed that the incorporation of rGO into the ZnO increased the photodegradation ability of the bare ZnO. The performance of the composite is also compared with the rGO-ZnO nanocomposite, where rGO was prepared by Hummer's method. rGO obtained from Tang Lau method formed stable and efficient composite with ZnO and exhibited higher activity compared to the composite, wherein rGO was prepared from conventional Hummer's method. Under UV light, the ZnO liberates photoelectrons which reacts with surface oxygen to form superoxide radicals (O ? 2 ) and (OH ? ) in the water medium. The rGO nanosheets could reduce the charge recombination during the reaction. The active species adsorbs the MO molecules and degrades into CO 2 , H 2 O and other byproducts. More than 3.5 times increase in the rate constant was observed for rGO-ZnO compared to the bare ZnO. © 2018 Elsevier B.V.Item A single step unique microstructural growth of porous colossal dielectric constant titanium oxide(Springer Verlag service@springer.de, 2019) Meti, S.; Hosangadi Prutvi, S.P.; Rahman, M.R.; Bhat K, U.K.New microstructure of TiO 2 grown in hydrothermal process is reported on. The influence of hydrothermal process parameters, such as heating temperature, on growth dynamics is also reported. The improvement in surface area and crystallinity are reached by the hydrothermal process, as compared to other growth techniques. The synthesized TiO 2 is characterized by XRD technique and subjected to Rietveld analysis. The results indicate that the obtained TiO 2 is of tetragonal structure. The results of other characterization techniques such as micrography, Raman spectroscopy and TGA are also reported. The obtained TiO 2 is tested for its electrical properties and it shows good dielectric strength in the flat band region from 40 Hz to 1 MHz. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Item Colossal dielectric permittivity of Nylon-6 matrix-based composites with nano-TiO2 fillers(Springer, 2020) Meti, S.; Bhat K, U.K.; Rahman, M.R.Herein, the nanocomposite films of Nylon-6 with reinforced nano-TiO2 were explored for their charge storage capacity. The high dielectric constant (?) of TiO2, along with its compatibility with Nylon-6, formed the basis for the present study. TiO2 nanoparticles were synthesized initially using hydrothermal technique. The microscopic uniformity and anatase-phase purity of the TiO2 nanoparticles were confirmed with the help of morphological and structural investigations. The effect of weight fraction of TiO2 in Nylon-6 was investigated to understand the robustness of the fabricated nanocomposites. The composite films with 5, 10 and 20 wt% of TiO2 in Nylon-6 matrix were prepared, and their dielectric behavior was explored by fabricating capacitors with parallel plate architecture. The composite film with 20 wt% TiO2 showed the highest dielectric parameters. The nanocomposite films have the exceptional dielectric quality with ? ~ 124 and low dielectric loss of 0.51 at 1 kHz. The colossal dielectric nature along with minimum sophistication in the film fabrication process makes the present nanocomposite to be a potential candidate for the various electronic devices. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Investigational study of mwcnt’s/silicon oxide nanoparticles/epoxy resin nanocomposite coating on mild steel for anticorrosion and mechanical properties(International Journal of Scientific and Technology Research editor@ijstr.org, 2020) Gujjar, S.V.; Prajapati, A.D.; Hunashyal, A.M.; Hallad, S.; Meti, S.Weathering of mild steel known as corrosion, affects the life span of engineering structures adversely. An attempt to enhance the durability of structure using Nanotechnology carried out in the present experimental work. Multi- Walled Carbon Nano Tubes were prepared by CVD method. For better dispersion of Multi- Walled Carbon Nano Tubes (MWCNT’s) and Silicon Oxide Nano particles were simultaneously ultrasonicated. The MWCNT’s/ SO/ Epoxy Nano composite coating effect on mild steel for corrosion behavior and mechanical properties were investigated. The anticorrosion property of the Nano composite coating was determined by immersion as well as salt spray method. Mechanical properties like tensile strength and scratch hardness were evaluated to compare with the plain mild steel and neat epoxy coated mild steel. For surface characterization, FESEM was conducted. The addition of MWCNTs and Silicon Oxide Nano particles in Epoxy resin improves the anticorrosion and mechanical properties of mild steel. © IJSTR 2020.Item Fabrication of Ag/PDMS-TiO2 flexible piezoresistive pressure sensor(Elsevier B.V., 2020) Kumari, K.; Rameshan, R.; ArunKumar, D.S.; Meti, S.; Rahman, M.R.In this study, TiO2 nanorods are grown on a flexible Polydimethylsiloxane (PDMS) substrate using the hydrothermal technique. The morphological, structural, compositional, optical properties and pressure sensing are investigated in detail by FESEM, XRD, EDX, UV–visible spectrophotometer, and piezoelectric studies. XRD demonstrates the pure rutile phase with a tetragonal structure is formed from deposited TiO2 thin film. FESEM images confirm the TiO2 nanorods with average dimensions length ~620 nm and diameter ~97 nm whereas the optical spectrum shows the strong light absorption in the UV region with bandgap 3.54 eV. The voltage is measured as a response to the applied mechanical load and the sensitivity of the pressure sensor is obtained as 2.56 × 10?5 V/N. The flexible pressure sensors (Ag/PDMS-TiO2) senses over a large pressure range and shows a linear response because of the adjustments in the volume of dielectric that makes the pressure inside the dielectric cavity to vary. © 2020 Elsevier B.V.Item Assessment of triboelectricity in colossal-surface-area-lanthanum oxide nanocrystals synthesized via low-temperature hydrothermal process(Springer, 2021) Meti, S.; Hosangadi Prutvi, H.P.; Rahman, M.R.; Bhat, K.U.Triboelectric nanogenerators (TENGs) have marked their applications in various fields, most importantly, in medical devices. The electrical output of the TENGs mainly concentrated on parameters such as electrode separation distance, applied mechanical pressure, surface charge density, and overlapping surface area. The surface area of the active layer in TENGs plays a crucial role. Given this, the present contribution is the first report on the utilization of lanthanum oxide (La2O3) as an active material with a large surface area (~ 72.33 m2/g) in TENGs. The nanocrystals of La2O3 have been successfully embedded into TENGs architecture through a high-quality screen-printed film with a Teflon-counter surface. The in-house test-rig of TENGs resulted in an output open-circuit voltage of 120 V and a short-circuit current of 23.7 ?A. Further, the maximum power density is 7.125 W/m2 at an external load resistance of 30 M?. These results suggest that La2O3 is a suitable contender in various self-powered devices. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Triboelectric effect based self-powered compact vibration sensor for predictive maintenance of industrial machineries(IOP Publishing Ltd, 2021) Hosangadi Prutvi, H.P.; Meti, S.; Bhat K, U.K.; Gupta, D.This article showcases a compact self-powered contact-mode triboelectric (TE) phenomenon-based vibration sensor for predictive maintenance of industrial machinery. The sensor has a suspended proof-mass that oscillates under external vibration and causes contact-separation between Teflon and zinc oxide (ZnO) films creating tribo signals, which are used for both sensing and powering mechanisms. For these sensors to be implemented in real-time applications, the sensor must be cost-effective, reliable, and repeatable. Hence, the active layer (ZnO film) is fabricated by an efficient process of microwave-assisted thermal decomposition followed by the established screen printing method. The sensor operates up to 400 Hz and is highly robust with no significant decay in signal strength even after 120 000 cycles tested at elevated stress values. The device produces a maximum voltage (V) of ±30 V, short circuit current of ±3 ?A, and can deliver a maximum power density of 0.5 W m-2, at 8 M? load resistance. In the frequency domain, the device generates a maximum V at 55 Hz and can charge 1 µF capacitor to 3.5 V in 25 s. To demonstrate the functionality of the sensor in a real application, it is implemented on a lab-scale vacuum pump to capture the system faults by analyzing the harmonic signatures. Thus, in this article, we have showcased end-to-end development of the sensor from material synthesis to device testing along with its signal processing techniques and proved that the sensor can readily be implemented in industrial environments as is. This article thus emphasis bridging the lab-to-market gap for TE devices as a self-powering sensor. © 2021 IOP Publishing Ltd.Item Influence of Copper Oxide Nanoparticles on AC Conductivity of Polyvinyl Alcohol-Polyaniline Polymer Blends(Springer, 2022) Kanavi, P.S.; Meti, S.; Fattepur, R.H.; Patil, V.B.Copper oxide (CuO) nanoparticles were synthesized using a simple co-precipitation method. CuO doped (0.2%, 0.4%, 0.6% and 1%) polyaniline (PANI)—polyvinyl alcohol (PVA) nanocomposites were prepared by solution casting techniques. The crystalline monoclinic phase of CuO was identified by XRD analysis. The peak widths in XRD spectra of PANI-PVA-CuO (PPC) become intense and sharp with the increase in loading of CuO, which implies the crystalline character of PPC that results in higher ionic diffusivity and conductivity. The CuO nanocrystal morphology, surface topography and thickness of the PPC films were recorded by scanning electron microscopy (FESEM). The chemical natures of the bonds were studied by the FTIR technique. The absorption spectra of CuO nanocrystals and PPC films were recorded using UV–visible spectroscopy. TGA and DSC techniques were used to examine the thermal stability of the PPC films. The prepared samples were kept to study electrical properties in the frequency range of 10 to 105 Hz in the temperature range of 30°C to 150°C. It was shown that as the applied frequency and temperature increased, the corresponding electrical conductivity increased abruptly. © 2022, The Minerals, Metals & Materials Society.Item Enhancing the electrochemical performance of ZnO anode by novel additive of MoS2–SnO2 nanocomposite for the zinc alkaline battery application(Springer, 2022) Prabukumar, C.; Meti, S.; Bhat K, U.K.ZnO nanorods and ZnO microrods are synthesized as the anode material for the Zn alkaline battery application. The present work studies the electrochemical performance of ZnO with regard to its size, morphology and MoS2–SnO2 nanocomposite as its additive towards the alkaline battery application. The properties, such as oxidation–reduction reaction, anti-corrosion behaviour, charge-transfer resistance and suppression of hydrogen evolution reaction (HER), are studied in detail. The structural characterization of ZnO samples is performed by using X-ray diffractometry. The morphological analysis of ZnO and MoS2–SnO2 nanocomposite is performed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The atomic absorption spectroscopy (AAS) is employed to determine the solubility of ZnO samples in KOH solution. The electrochemical properties of the bare ZnO and the ZnO with MoS2–SnO2 additive (MoS2–SnO2/ZnO) samples are characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), cathodic polarization and Tafel polarization techniques. The ZnO with nanorod morphology shows better electrochemical performance than ZnO microrods and ZnO nanoparticles with sphere-like or plate-like morphology. The addition of MoS2–SnO2 nanocomposite with the ZnO improved the electrochemical activity, suppressed the HER activity and improved the anti-corrosion behaviour of the ZnO samples. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Emphasized temperature dependent electrical properties study of fabricated ZnO/PVA/PANI nanocomposite films(Elsevier Inc., 2022) Kanavi, P.S.; Meti, S.; Fattepur, R.H.; Patil, V.B.Polyvinyl alcohol-Polyaniline composite films with different amounts of zinc oxide (ZnO) (0.2%, 0.4%, 0.6% and 1%)were prepared by in situ polymerization followed by film casting and drying. The samples, ZnO and PPZ films, were characterized by various techniques. The presence of ZnO in PPZ films was confirmed by the X-Ray Diffractometer (XRD). The surface morphology of the ZnO and PPZ films were examined by the Field-Emission Scanning Electron Microscopy(FESEM). The formation of absorption bonds corresponding to the PPZ films were illustrated by the Fourier Transform Infrared Spectroscope (FTIR)analysis. The films were found to be stable up to 150 °C, which was confirmed from the Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analyzer (TGA) technique. The absorption peaks of PPZ, around visible and UV region, was studied by the UV–Vis spectra. The electrical conductivity plots obtained from the impedance analyzer, between frequency ranges of 10 Hz to 100 kHz, show that the increase in concentration and temperature of the samples resulted in the higher conductivity of the PPZ films. For 1% ZnO concentration at 150 °C, the AC conductivity of PPZ1 was found to be 20.06 S/m. Such conductivity behavior samples render the applicability of the PPZ films. © 2022