Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
6 results
Search Results
Item Novel Fe-Ni-Graphene composite electrode for hydrogen production(Elsevier Ltd, 2015) Badrayyana, S.; Bhat, D.K.; Shenoy, U.S.; Ullal, Y.; Hegde, A.We have developed a novel, efficient and economical composite electrode for hydrogen production. The electrode has been formed by embedding graphene in the Fe-Ni matrix via room temperature electrodeposition. The obtained active coatings have been tested for their efficiency and performance as electrode surfaces for hydrogen evolution reaction (HER) in 6 M KOH by cyclic voltammetry and chronopotentiometry techniques. The coating obtained at 60 mA cm-2 exhibited approximately 3 times higher activity for hydrogen production than that of binary Fe-Ni alloy. Addition of graphene to electrolyte bath resulted in porous 3D projections of nano-sized spheres of Fe-Ni on the surface of graphene, which effectively increased the electrochemically active surface area. XPS analysis results showed the equal distribution of both Ni metal and NiO active sites on the composite. The addition of graphene favoured the deposition of metallic nickel, which accelerated the rate determining proton discharge reaction. All these factors remarkably enhanced the HER activity of Fe-Ni-Graphene (Fe-Ni-G) composite electrode. The Tafel slope analysis showed that the HER follows Volmer-Tafel mechanism. The structure-property relationship of Fe-Ni-G coating has been discussed by interpreting field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis results. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Item Novel RGO-ZnWO4-Fe3O4 nanocomposite as high performance visible light photocatalyst(Royal Society of Chemistry, 2016) Mohamed, M.M.J.; Shenoy, U.S.; Bhat, D.K.A novel RGO-ZnWO4-Fe3O4 nanocomposite is synthesized by a microwave irradiation method and its catalytic activity for the photo degradation of Methylene Blue (MB) is investigated. The prepared nanocomposites are characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible spectroscopy. The visible light photocatalytic activities of the prepared nanocomposites are investigated using a MB dye solution. It is noteworthy that RGO-ZnWO4-Fe3O4 nanocomposites exhibited relatively high photocatalytic activity compared to ZnWO4-RGO and pure ZnWO4 on MB in aqueous solution. This enhanced rate is due to the ability of the graphene in the RGO-ZnWO4-Fe3O4 composite to support carrier exploitation efficiently by tolerating the photo excited electron-hole pairs and thus encouraging oxidative degradation of the pollutants. This work could be extended to other organic pollutants as well and could provide new insights into ternary nanocomposites as high performance photocatalysts and their application in waste water treatment. © 2016 The Royal Society of Chemistry.Item RGO/ZnWO4/Fe3O4 nanocomposite as an efficient electrocatalyst for oxygen reduction reaction(Elsevier B.V., 2017) Mohamed, M.; Mutyala, S.; Mathiyarasu, J.; Bhat, D.K.Development of low cost, environmental friendly and noble metal free catalyst materials with excellent performance is essential for commercialization. In fact, this is the need of the day too. Herein, we report a facile microwave irradiation method for the synthesis of novel RGO/ZnWO4/Fe3O4 cathode catalysts for the oxygen reduction reaction (ORR) in alkaline medium. The structural and morphological features of synthesized materials are fully examined using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM). The chemical composition and elemental analysis of the catalyst is investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques. Efficiency of RGO/ZnWO4/Fe3O4 catalyst material for oxygen reduction reaction (ORR) in 0.1 M KOH is reported. The activity of catalyst is determined by linear sweep voltammogram (LSV) and rotating disk electrode (RDE) measurements in O2 saturated 0.1 M KOH electrolyte. RGO/ZnWO4/Fe3O4 catalyst exhibits higher ORR activity than RGO, ZnWO4, RGO/ZnWO4 and its electrocatalytic performance is comparable to Pt/C material and is superior to it in stability and methanol tolerance. Further, it is determined that process follows a direct four electron reaction pathway. These combined results strongly signpost that RGO/ZnWO4/Fe3O4 composite can function as an economic noble metal free ORR cathode catalyst for energy applications. © 2017 Elsevier B.V.Item NiWO4-ZnO-NRGO ternary nanocomposite as an efficient photocatalyst for degradation of methylene blue and reduction of 4-nitro phenol(Elsevier Ltd, 2017) Mohamed, M.; Shenoy, U.S.; Bhat, D.K.A novel NiWO4-ZnO-NRGO ternary nanocomposite has been efficiently synthesized by decorating nitrogen doped reduced graphene oxide (NRGO) with zinc oxide and nickel tungstate nanoparticles via a facile microwave irradiation technique and its capability to catalyze photodegradation of methylene blue (MB) dye in aqueous solution and reduction of 4-nitro phenol (4-NP) to 4-amino phenol (4-AP) using sodium borohydride was explored. The as-synthesized nanocomposite was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, energy dispersive X-ray (EDX) analysis, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity of the as-synthesized nanocomposite estimated through the photodegradation of MB under visible light irradiation showed 9 times improvement over pure NiWO4. It also showed excellent catalytic activity in reduction of 4-NP to 4-AP. The material also showed excellent stability and reusability. The entire study revealed that the novel NiWO4-ZnO-NRGO ternary nanocomposite can act as a promising bifunctional photocatalyst for environmental remediation and industrial application. © 2017 Elsevier LtdItem Electrodeposition of Ni-Mo-rGO composite electrodes for efficient hydrogen production in an alkaline medium(Royal Society of Chemistry, 2018) Shetty, S.; Mohamed, M.; Bhat, D.K.; Hegde, A.The mechanism and kinetics of the hydrogen evolution reaction (HER) on Ni-Mo-rGO composite electrodes in 1.0 M KOH solution were investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and potentiodynamic polarization techniques. Ni-Mo-rGO composite coatings were deposited on a copper substrate by an electrodeposition method at a current density (c.d.) ranging from 1.0 to 4.0 A dm-2. The change in surface morphology and chemical composition was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) analysis and X-ray photoelectron spectroscopy (XPS). It was shown that the carbon content of the composite coatings was affected by c.d. With the increase in the carbon content in the Ni-Mo-rGO composite coatings, the onset potential was decreased and the exchange current density was increased during the HER. The minimum onset potential and maximum exchange current density of Ni-Mo-rGO composite coatings for the HER were -401.6 mV and 4.31 ?A cm-2. The best composite coating exhibited a maximum peak current density of -0.517 A cm-2 at -1.6 V, which is approximately 3 times better than that of the binary Ni-Mo alloy, indicating the best activity for hydrogen production. The potentiodynamic polarization measurements revealed that composite coatings are much more resistant to corrosion than binary alloy coatings. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Novel NRGO-CoWO4-Fe2O3 nanocomposite as an efficient catalyst for dye degradation and reduction of 4-nitrophenol(Elsevier Ltd, 2018) Mohamed, M.M.J.; Shenoy, S.; Bhat, D.K.Novel NRGO-CoWO4-Fe2O3 (N-doped reduced graphene oxide-cobalt tungstate-iron oxide) ternary nanocomposite was prepared by using simple microwave method. The synthesized materials were thoroughly characterized by X-ray diffraction (XRD) studies, Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, photoluminescence (PL) and UV-Visible spectroscopy. The nanocomposite was studied for its catalytic activity in degradation of methylene blue (MB) and reduction of 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP). The observed results of catalytic efficiency and rate constants indicated that the NRGO-CoWO4-Fe2O3 nanocomposite can perform as an excellent catalyst compared to other composite materials. The detailed experimental study revealed that this ternary nanocomposite shows a great promise as a candidate for various environmental applications. © 2018 Elsevier B.V.