Faculty Publications

Now showing 1 - 4 of 4

Effect of graphene oxide loading on plasma sprayed alumina-graphene oxide composites for improved anticorrosive and hydrophobic surface
(IOP Publishing Ltd custserv@iop.org, 2019) Amudha, A.; Shashikala, H.D.; Asiq Rahman, O.S.; Keshri, A.K.; Nagaraja, H.S.
Alumina is a widely used anticorrosive coating material for protection of metal surfaces. The graphene oxide (GO)-Alumina composite coatings can enhance the anticorrosion property of carbon steel surfaces used in an industrial scale. In the present work, the spray dried graphene oxide nanoplatelets of 0, 0.5, 1, 1.5 and 2 wt% reinforced alumina (?-Al2O3) were deposited on the low carbon steel substrate by Atmospheric Plasma Spray (APS) technique. The GO-Alumina nanocomposite coatings are characterised using XRD, FE-SEM, HR-TEM and Raman Spectroscopy. The electrochemical corrosion behaviour of the coatings on carbon steel has been examined using three electrode electrochemical method in 3.5 wt% NaCl electrolyte. A remarkable improvement in the corrosion resistance (with a corrosion current density of 0.01 nAcm-2) of about six orders with respect to pristine alumina was observed. The wettability tests revealed that, with 1.5 and 2 wt% graphene oxide nanoplatelets addition, the surface coating turned out to be hydrophobic with contact angle of 127°, from hydrophilic with contact angle 36°, which complements the anticorrosion results. The in situ reduction of GO to r-GO by APS deposition and bridging of alumina splats by the GO sheets accounts for observing the superior performance of the composite coatings. © 2019 IOP Publishing Ltd.
Enhanced corrosion resistance of atmospheric plasma-sprayed zirconia–GNP composite by graphene oxide nanoplatelet encapsulation
(Springer, 2020) Amudha, A.; Hosakoppa S, N.; Holavanahalli Doraiswamy, S.
The unique natural diffusion barrier property of graphene plays a crucial role in protecting the carbon steel substrates from corrosion, particularly using graphene oxide nanoplatelets (GNP)–zirconia (ZrO2) composites. In the present work, atmospheric plasma spraying (APS) technique has been used to coat both the spray-dried pristine ZrO2 and ZrO2–(0.5, 1.0, 1.5 and 2) wt% GNP composite on the carbon steel substrate. The retention of GNPs in the coating was confirmed using XRD, Raman spectroscopy, TEM, FE-SEM, and EDAX techniques. The corrosion properties of the coatings in 3.5 wt%NaCl electrolyte were studied using linear polarization resistance and electrochemical impedance spectroscopy technique. This reveals the enhanced charge transfer resistance, decreased corrosion current density and corrosion rate of ZrO2–GNP composite. Further, the corrosion rate of ZrO2–2 wt% GNP coating is 130 times less than the plasma-sprayed ZrO2. Compared to 0.5, 1.0 and 1.5 wt% GNP added zirconia coatings, ZrO2–2 wt% GNP displayed the highest stability up to 14 days in 3.5% NaCl electrolyte. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Mesoporous NiWO4@rGO nanoparticles as anode material for lithium-ion battery
(Taylor and Francis Ltd., 2023) Brijesh, B.; Amudha, A.; Mukesh, M.P.; Sagar, L.; Moolayadukkam, S.; Nagaraja, H.S.
Herein, we have tried to explore the charge storage properties of mesoporous NiWO4 as an anode in lithium-ion batteries (LIB). A one pot-solvothermal synthesis is used to tweak the properties of mesoporous NiWO4 nanoparticles with reduced graphene oxide (rGO) for the first time and explored the LIB anode applications. Materials are well characterised using structural and morphological characterisations to corroborate the relation between the electrochemical properties and the graphene addition. At 100 mA g−1, the NiWO4@rGO (NWZC) exhibits initial discharge capacity of 1439 mAh g−1, which is more than that of NiWO4 (NWZ). Both NWZ and NWZC display initial coloumbic efficiency of 91.65% and 62.1%. After 500 cycles, the coloumbic efficiency of the NWZ and NWZC is above 99%. The improved lithium-ion storage characteristics of the NWZC may be from the synergetic effect between NiWO4 and r-GO. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
Enhanced Electrochemical Performance of Low-Content Graphene Oxide in Porous Co3O4 Microsheets for Dual Applications of Lithium-Ion Battery Anode and Lithium-Ion Capacitor
(Springer, 2024) Lakshmi Sagar, G.; Brijesh, K.; Mukesh, P.; Amudha, A.; Bhat, K.S.; Nagaraja, H.S.
The enhancement of electrochemical performance in lithium-ion battery (LIB) anode materials through nanostructures is of paramount importance, facilitated by the synergistic integration of these unique architectures with active materials, which increases the availability of active sites and decreases the diffusion path for lithium ions. In this investigation, we successfully synthesized cobalt oxide (Co3O4) microsheets composed of small nanoparticles (measuring 28–33 nm), employing a straightforward hydrothermal process followed by annealing. Furthermore, to enhance the composite’s ability to endure volume changes and increase its electrical conductivity, we created a Co3O4/reduced graphene oxide (rGO) composite embedding a judicious amount of graphene oxide (GO). This engineered composite exhibited remarkable specific discharge capacity of 1081 mAh g−1 at 100 mA g−1, a substantial improvement over the pristine material’s capacity of 718 mAh g−1. The composite demonstrated reduced irreversible capacity loss relative to the pristine counterpart and approached a reversible capacity of nearly 99%. Even after 400 cycles under the demanding conditions of high current density of 500 mA g−1, the composite managed to retain 81% of its initial capacity, underscoring its exceptional cycling stability. Moreover, the application of the Co3O4/rGO//carbon black (CB) assembly in lithium-ion capacitors (LIC) yielded notable energy density of 15.6 Wh kg−1 at elevated power density of 1007 W kg−1. These LIC devices demonstrated robust cyclic stability across extended cycles, sustaining 56% of their initial capacity after 2000 cycles while operating at a current density of 2 A g−1. Graphical Abstract: [Figure not available: see fulltext.]. © 2024, The Minerals, Metals & Materials Society.

Faculty Publications

Browse

Filters

Settings

Sort By

Results per page

Search Results