Faculty Publications
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Item Photoelectrochemical studies on metal-doped graphitic carbon nitride nanostructures under visible-light illumination(MDPI, 2020) Reddy, I.; Jayashree, N.; Manjunath, V.; Kim, D.; Shim, J.Recently, the engineering of optical bandgaps and morphological properties of graphitic carbon nitride (g-C3N4) has attracted significant research attention for photoelectrodes and environmental remediation owing to its low-cost synthesis, availability of raw materials, and thermal physical–chemical stability. However, the photoelectrochemical activity of g-C3N4-based photoelectrodes is considerably poor due to their high electron–hole recombination rate, poor conductivity, low quantum efficiency, and active catalytic sites. Synthesized Ni metal-doped g-C3N4 nanostructures can improve the light absorption property and considerably increase the electron–hole separation and charge transfer kinetics, thereby initiating exceptionally enhanced photoelectrochemical activity under visible-light irradiation. In the present study, Ni dopant material was found to evince a significant effect on the structural, morphological, and optical properties of g-C3N4 nanostructures. The optical bandgap of the synthesized photoelectrodes was varied from 2.53 to 2.18 eV with increasing Ni dopant concentration. The optimized 0.4 mol% Ni-doped g-C3N4 photoelectrode showed a noticeably improved six-fold photocurrent density compared to pure g-C3N4. The significant improvement in photoanode performance is attributable to the synergistic effects of enriched light absorption, enhanced charge transfer kinetics, photoelectrode/aqueous electrolyte interface, and additional active catalytic sites for photoelectrochemical activity. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Item Vanadium-doped graphitic carbon nitride for multifunctional applications: Photoelectrochemical water splitting and antibacterial activities(Elsevier Ltd, 2021) Reddy, I.N.; Reddy, L.V.; Jayashree, N.; Venkata Reddy, C.V.; Cho, M.; Kim, D.; Shim, J.Bulk graphitic carbon nitride (g-C3N4) exhibits limited water splitting efficiency due todrawbacks including high charge recombination rate, low electrical conductivity, poor quantum efficiency, and few adsorption and active catalytic sites. Herein, we report V-doped g-C3N4 nanoarchitectures prepared via direct calcination of urea and ammonium metavanadate. The obtained V-doped g-C3N4 nanostructures not only improved the visible light absorption property but also increased the charge separation and transportation, resulting in extremely enhanced water splitting activity. The structural, morphological, and optical analysis results confirmed the successful incorporation of V into the host g-C3N4 material, and electrochemical impedance spectroscopy measurements revealed the charge carrier dynamics. Compared to the pristine g-C3N4 photoelectrode, the optimized 0.3 mol% V-doped g-C3N4 photoelectrode showed a considerably higher photocurrent density (0.80 mA cm-2). The enhancement of the catalytic performance could be attributed to the synergistic effects of prolonged light absorption, improved transfer of electrons and holes, and extra active catalytic sites for water splitting. Further, the optimized 0.3 mol% V-doped g-C3N4 sample showed an antibacterial activity higher than that of the undoped photocatalyst. © 2020 Elsevier LtdItem Photoelectrochemical water oxidation kinetics and antibacterial studies of one-dimensional SiC nanowires synthesized from industrial waste(Springer Science and Business Media Deutschland GmbH, 2021) Reddy, I.N.; Sreedhar, A.; Pallavolu, M.R.; Reddy, L.V.; Cho, M.; Kim, D.; Jayashree, N.; Shim, J.Silicon wafers are significantly utilized in integrated circuits and memory devices for the fabrication of novel semiconductor devices. As a result, a substantial amount of silicon wastes are generated every year. But recycling process of pure silicon waste is expensive with an additional problem related to chemical waste generation. Thus, the possibility of inevitable silicon waste conversion into potential nanostructures is not only beneficial for the semiconductor industry but also resolves current e-waste pollution. Hence, we successfully achieved hexagonal silicon carbide (SiC) nanowires under a strategic combination of waste silicon wafers and graphite powder by robust high-energy ball milling and heat treatment approaches. Structural, morphological, chemical, and optical properties of SiC nanowires are systematically studied by XRD, SEM, TEM, XPS, and optical absorbance. This facile experimental technique recognized the value of SiC nanowire generation for exploring multifunctional photoelectrochemical (PEC) water splitting and antibacterial activity. Accordingly, SiC nanowires achieved a photocurrent density of about 0.21 mA cm?2 vs. Ag/AgCl, which demonstrates enhanced light absorption capacity under reduced charge carrier recombination. Moreover, SiC nanowires prevailed decrement in the charge carrier resistance (27.53 ?) under light state compared to the dark state (26.76 ?). Specifically, potentiodynamic studies revealed superior exchange current density (? 3.17 mA cm?2), Tafel slope (80.1 mV dec?1), and limiting diffusion current density (? 1.49 mA cm?2) under light state than the dark state. Also, these results are certainly applicable for superior antibacterial activity against E. coli and L. monocytogenes about 90% and 75% under visible light, respectively. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Item Decentralised priority-based shortest job first queue model for IoT gateways in fog computing(Inderscience Publishers, 2022) Jayashree, N.; Babu, B.S.; Talawar, B.An increased growth in time-critical IoT applications, led to a rise in real-time resource requirements. The stringent deadlines on latency have made IoT applications move out from far away cloud servers to distributed fog computing devices infrastructure which is available locally. To meet the touchstones of deadlines and processing times, there is a need to prioritise the job scheduling through the IoT gateways to appropriate fog devices. Studies showed that the queuing models exhibit uncertainties in choosing suitable computing devices, applying priorities to the jobs, deadline achievements, and minimum latency constraints. In this paper, we propose a Decentralised Priority-based Shortest Job First (DPSJF) queuing model for the IoT gateways for a fog computing infrastructure, which uses the priority-based jobs sorting technique to achieve better performance and also overcome most of the uncertainties in queuing. © © 2022 Inderscience Enterprises Ltd.