Faculty Publications

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    Dynamic mechanical analysis and free vibration behavior of intra-ply woven natural fiber hybrid polymer composite
    (SAGE Publications Ltd info@sagepub.co.uk, 2016) RAJESH, M.; Jeyaraj, P.
    Influence of nature of weaving pattern and intra-ply hybridization of natural fibers on dynamic mechanical and free vibration characteristics of woven banana/jute polyester composite has been investigated. Results revealed that basket-type composite has better dynamic properties due to uniform stress distribution in both warp and weft directions. Warp jute fiber and weft banana fiber (WJWB) and both warp and weft banana and jute fiber (WAWBJ) intra-ply hybrid composites have better dynamic mechanical behavior as relatively stronger fiber is oriented along the loading direction. Experimental modal analysis carried out on beam-like samples revealed that warp and weft banana and jute fiber intra-ply hybrid composite has better natural frequencies while huckaback woven and warp banana fiber and weft jute fiber composites have better modal damping factors. © The Author(s) 2015.
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    Enhanced Power Density of Graphene Oxide–Phosphotetradecavanadate Nanohybrid for Supercapacitor Electrode
    (Springer, 2021) Maity, S.; Anandan Vannathan, A.A.; Kumar, K.; Das, P.P.; Mal, S.S.
    Successful exploration of supercapacitor (SC) material to integrate with high energy and high power density storage device still remains a daunting challenge. Conducting carbon nanostructures have been primarily used for this purpose; however, most of their surface area remains unutilized throughout the storage process. Herein, a new type of hybrid material has been reported by effectively using active sides of carbon nanostructures. Insertion of faradaic-type polyoxometalates (POMs), namely phosphotetradecavanadate (Na7[H2PV14O42], hereafter described as PV14), into the graphene oxide (GO) matrix creates a novel hybrid material for SC applications. Owing to the formation of nanohybrid, it can store charges both electrostatically and electrochemically. PV14/GO composite’s electrochemical behavior in different electrolyte (acidic/neutral) solutions shows different types of characteristics. The PV14/GO composite as a working electrode exhibits a high galvanostatic capacitance of 139 F/g while maintaining at a power density of 97.94 W/kg in 0.25 M H2SO4 electrolyte. The specific energy density was also found out to be around 56.58 Wh/kg at a 5 mV/s scan rate for the same electrolyte. Furthermore, in 1 M Na2SO4 solution, PV14/GO composite demonstrates a specific capacitance of 85.4 F/g at a scan rate of 5 mV/s. The equivalent series resistance for the device was found to be approximately 0.51 ? with a circuit resistance of 3.881 ?, using electrochemical impedance spectroscopy. The cell capacitance, employing the Nyquist plot, was calculated to be around 2.78 mF. © 2021, ASM International.
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    Imidazole-Pyrene Hybrid Luminescent Materials for Organic Light-Emitting Diodes: Synthesis, Characterization & Electroluminescent Properties
    (Elsevier B.V., 2021) Umasankar, G.; Ulla, H.; Madhu, C.; Gontu, G.R.; Shanigaram, B.; Nanubolu, J.B.; Bhanuprakash, B.; Karunakar, G.V.; Satyanarayan, M.N.; Rao, V.J.
    A series of multichromophoric, pyrene-imidazole-phenyl based hybrid luminescent small molecules (PA, PI, PnB, PtB, PoM and PnDM) with different donating groups at the para position of the phenyl attached to N1 position of imidazole moiety were designed, synthesized, and characterized, for use in blue organic light-emitting diodes (OLEDs). The photophysical, thermal and electrochemical properties of the molecules were systematically investigated. All the molecules displayed delayed fluorescence at room temperature with a lifetime ranging from 7.1 to 8.5 µs. The synthesized fragment molecules (tetraphenyl-imidazoles: IA, IoM and InDM) revealed high triplet energies of ~ 2.90eV. Glass transition temperatures determined to range from 77°C to 123°C and decomposition temperatures are found to be above 280°C. The molecules possess appropriate HOMO and LUMO energy levels for effective charge injection. The crystal structure for PI is reported. OLED devices were fabricated based on the pyrene-imidazole-phenyl hybrids as emitters and as dopants with CBP as host. OLED devices with PI doped (5% wt.) with CBP exhibits excellent device performance with a current efficiency of 9.82 cd/A, the power efficiency of 8.32 lm/W and external quantum efficiency of 4.64%. © 2021
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    Effect of similar and dissimilar interface layers on delamination in hybrid plain woven glass/carbon epoxy laminated composite double cantilever beam under Mode-I loading
    (Elsevier B.V., 2021) Suman, M.L.J.; Murigendrappa, S.M.; Kattimani, S.
    Effect of similar and dissimilar interface layers on delamination in hybrid plain woven glass/carbon epoxy laminated composite double cantilever beam under Mode-I loading has been investigated experimentally and analytically. Glass-glass, glass-carbon interface layers in three different configurations of hybrid plain woven glass/carbon epoxy laminated composites were fabricated. Valvo's mode partition method from the literature is utilised to compute individual modal contributions and total fracture toughness of the hybrid composite laminates. Mode-I fracture toughness contribution is compared with standard data reduction schemes of ASTM D5528-13. The comparison reveals that Valvo's mode partition method considers mode-mixity and provides conservative results. The Valvo's mode partition does not require any correction factors including curve fitting, it provides a straightforward method for evaluating fracture toughness as they are based on the mechanics of composite materials. The comparison of R-curves of hybrid configurations reveal that the insertion of carbon with glass at the interface of symmetric hybrid configuration enhances initial fracture toughness and stabilises whereas, with the change in layer configuration of anyone arm of the double-cantilever beam, the crack growth trend is also affected irrespective of same interface layers. The fractography analysis of delamination surfaces reveals that crack propagation through a resin-rich layer creates a rougher fracture surface resulting in higher energy dissipation as compared to crack propagation through resin-rich pockets. © 2021 Elsevier Ltd
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    Activated carbon- supported Vanado-nickelate (IV) based hybrid materials for energy application
    (Elsevier Ltd, 2021) Maity, S.; BM, N.; Kella, T.; Shee, D.; Das, P.P.; Mal, S.S.
    The rapid development of supercapacitor (SC) technology leads to increased demand for nanofabrication of novel and effective electroactive hybrid materials for next-generation energy storage devices. Herein, nickel tetradecavanadate, K2H5[NiV14O40](NiV14), is doped into porous activated carbon (AC), for the first time, in different wt.% in order to investigate the homogeneous loading of the inorganic metal-oxide component on the AC matrix. The resulting complex, AC-NiV14, is found to have possessed an enhanced electrochemical characteristic (for both symmetric and asymmetric SC cell), which operates at a significantly higher potential of 1.2 V. The combination of the double-layer capacitance (EDLC) and the redox-active polyoxometalate cluster leads to an intrinsic increase in specific capacitance (capacity) (from 45.3 Fg?1 (54.4 Cg?1) for AC to 316 Fg?1 (379.2 Cg?1) for 15 wt.% AC-NiV14 at a current density of 1 Ag?1). It was also observed that there is an increase of 20% in the operating voltage compared to conventional AC supercapacitors with acidic aqueous electrolytes. Firstly, symmetric supercapacitor's electrochemical performances of various wt.% of NiV14 composition were studied in acidic aqueous electrolyte (0.5 M H2SO4) solution. We observed that the 15 wt.% of AC-NiV14 hybrid electrode showed remarkable specific energy value (~63.2 Wh kg?1) compared with pristine AC and NiV14 electrodes, separately. Besides, the asymmetric layout (AC//AC-NiV14) increased the potential window up to 1.5 V and enhanced the specific energy and power values (90.1 Whkg?1 and 2400 Wkg?1, respectively), with 98% coulombic efficiency. Meanwhile, the AC-NiV14//NiV14 asymmetric cell possesses a specific capacitance (capacity) of 375 Fg?1 (450 Cg?1) with a maximum power of 3140 Wkg?1 at the high current density of 2 Ag?1. © 2021 Elsevier Ltd
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    Simple carbazole derivatives with mono/dimethoxyphenylacrylonitrile substituents as hole-transporting materials: Performance studies in hybrid perovskite solar cells
    (John Wiley and Sons Inc, 2021) Keremane, K.S.; Vasudeva Adhikari, A.V.
    Herein, we report the development of two new low-cost 9-(2-ethylhexyl)-9H-carbazoles carrying the mono/dimethoxyphenyl substituted cyanovinylene units symmetrically at 3- and 6-positions of the carbazole core (CZ1-2), as potential hole-transporting materials (HTMs) for perovskite solar cell (PSC) application. The current work highlights their structural, photophysical, electrochemical, theoretical, and photoelectrochemical studies, including evaluation of their structure-property relationships. Evidently, the optical studies showcased their excellent fluorescence ability due to their push-pull natured structure; their ?abs and ?emi values were found to be in the order of 410–430 nm and 530–560 nm, respectively, with a bandgap in the range of 2.5–2.6 eV. Further, their theoretical studies, performed by using the DFT simulations clearly revealed in-depth information on their molecular geometries, FMO, and electronic properties. Finally, new PSCs were fabricated successfully by employing CZ1-2 as HTMs to evaluate their photovoltaic performances. Their results indicated that the device with CZ1 displayed enhanced PCE of 2.55% (JSC= 7.85 mA/cm2, VOC= 0.79 V and FF = 40%) than the cell with CZ2 (PCE = 1.71%, JSC= 8.15 mA/cm2, VOC = 0.4 V, FF = 49%) and the obtained data are well comparable with reference, Sipro-OMeTAD (PCE = 4.76%, JSC= 12.27 mA/cm2, VOC = 0.84 V, FF = 45%). Conclusively, the study furnishes a deeper understanding of the intricacies involved in the structural modification of in low-cost HTM in achieving an enhanced performance of the devices. © 2021 The Authors. Electrochemical Science Advances published by Wiley-VCH GmbH.
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    Organic cation linkers polyoxomolybdate-polypyrrole nanocomposite-based supercapacitors
    (Springer Science and Business Media Deutschland GmbH, 2021) Muhammed Anees, P.K.; Anandan Vannathan, A.; Kella, T.; Shee, D.; Mal, S.
    A few new hybrid electrode materials have been synthesized and immobilized for the next-generation energy storage device. The hybrid electrodes PVMo11-TBA, PVMo11-BTA, PVMo11-TBP, PVMo11-TBA-PPy, PVMo11-BTA-PPy, and PVMo11-TBP-PPy were well characterized by NMR, XRD, FTIR, FESEM, BET, and tested for electrochemical performance. Among these hybrid electrode materials, the PVMo11-TBA-PPy electrode shows a high specific capacitance of 144.37 F/g at a 1A/g current density and incredible power and energy density of 1100.16 W/kg and 15.28 Wh/kg, respectively. The high electrode’s capacitance was due to the synergistic effect between the PPy and TBA-PVMo11 and high ionic diffusion compared with other synthesized electrodes. It also exhibited high cycle stability of 72.78% after 4500 cycles at 1 M H2SO4 electrolyte. The EIS offers a lower ESR value of 0.72 ohms for the PVMo11-TBA-PPy than PVMo11-TBA, indicating the rapid charge/discharge rate. On the other hand, the PVMo11-BTA-PPy and PVMo11-TBP-PPy electrodes showed lower capacitance values of 26.98 and 19.53. F/g at 0.4 and 1 A/g current density, respectively. Lowering the capacitance could be the prevention of the interaction of organic cations with the counter polyanion. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Polyoxomolybdate-Polypyrrole-Graphene Oxide Nanohybrid Electrode for High-Power Symmetric Supercapacitors
    (American Chemical Society, 2021) Maity, S.; Je, M.; Biradar, B.R.; Chandewar, P.R.; Shee, D.; Das, P.P.; Mal, S.
    Supercapacitors have emerged as one of the most promising candidates for high-performance, safe, clean, and economical routes to store and release of nonfossil energy. Designing hybrid materials by integrating double-layer and pseudocapacitive materials is crucial to achieving high-power and high-energy storage devices simultaneously. Herein, we synthesized a polyoxomolybdate-polypyrrole-graphene oxide nanohybrid via a one-pot reaction. The inclusion of polypyrrole enables a uniform distribution of the polyoxomolybdate clusters; it also confines the restacking of graphene oxide nanosheets. The structural and morphological analysis to unveil the nanohybrid architecture implies excellent interfacial contact, enabling fast redox reaction of polyanions, and a quick transfer of charge to the interfaces. Electrochemical characteristics tested under a two-electrode system exhibit the highest capacitance of 354 F g-1 with significantly high specific energy and power of 49.16 Wh kg-1 and 999.86 W kg-1, respectively. In addition, the cell possesses a high-rate capability and long cycle life by maintaining 96% of its capacitance over 5000 sweeping cycles. The highest specific power of ?10 »000 W kg-1 was computed with Coulombic efficiency of 92.30% at 5 A g-1 current density. Electrochemical impedance spectroscopy additionally reveals enhanced redox charge transfer due to double hybridization. Furthermore, it also demonstrates the impedance and capacitive behavior of supercapacitor cells over a definite frequency regime. ©
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    Dynamic characterization of hybrid composite material of rotor-bearing support system
    (Taylor and Francis Ltd., 2022) Gonsalves, T.H.; Garje Channabasappa, M.K.; Motagondanahalli Rangarasaiah, R.; Joladarashi, S.
    In this paper, the dynamic characterization of hybrid composite material of carbon-epoxy sandwiched by steel is presented from the rotor-bearing system perspective. The tensile and flexural strengths of the hybrid material are investigated followed by the detailed damping estimation using modal testing in cantilever mode and dynamic mechanical analysis in double cantilever mode. The experimental characterization results obtained in this work have fundamentally ascertained the mechanical and dynamic behavior of hybrid composite material for the intended application. © 2020 Taylor & Francis Group, LLC.
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    Polyoxovanadate-Activated Carbon-Based Hybrid Materials for High-Performance Electrochemical Capacitors
    (Institute of Physics, 2022) Anandan Vannathan, A.; Chandewar, P.R.; Shee, D.; Mal, S.S.
    Two different polyoxovanadates derivatives, K5MnIVV11O32.10 H2O (MnV11) and K7MnIVV13O38.18 H2O (MnV13), have been studied to evaluate their electrochemical performance. These polyoxovanadates were deposited on activated carbon (AC) to prepare AC-MnV11 and AC-MnV13 composites. The electrochemical performance of the AC-MnV11 electrode exhibits the remarkable specific capacitance of 479.73 F g-1 at a current density of 0.6 A g-1, along with incredible specific power and energy of 960 W kg-1. Likewise, the AC-MnV13 exhibits a specific capacitance of 357.33 F g-1 at the current density of 0.6 A g-1 with a specific energy of 71.46 Wh kg-1. Interestingly, the AC-MnV11 could light up the red and yellow color LED bulbs for a duration of 80 and 60 s, respectively, indicating a considerable specific power of the material. The AC-MnV13 electrode shows significantly less lighting up during the 65 and 30 s period with red and yellow LED bulbs. © 2022 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.