Browsing by Author "Mohamed, M.J."

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    Development of multilayer Sn-Ni alloy coating by pulsed sonoelectrolysis for enhanced corrosion protection
    (Royal Society of Chemistry, 2016) Shetty, S.; Mohamed, M.J.; Bhat, D.; Hegde, A.C.
    Multilayer Sn-Ni alloy coating has been developed electrochemically on mild steel using an ultrasound effect, as a tool to modulate mass transfer process at electrical double layer, during deposition. Sn-Ni coatings having alternate layers of alloys of different compositions were developed on a nano/micrometric scale by pulsing sonicator ON (tON) and OFF (tOFF), periodically. The composition modulated multilayer alloy (CMMA) Sn-Ni coatings have been deposited by inducing the ultrasound field periodically at optimal current density. Corrosion performances of ultrasound-assisted multilayer Sn-Ni alloy coatings have been evaluated by electrochemical methods. Corrosion data revealed that CMMA Sn-Ni coating, developed using pulsed ultrasonic field and having 150 layers, represented as (Sn-Ni)2/2/150, is the most corrosion resistant, compared to its monolayer alloy coatings developed by both with/without ultrasound effect. Corrosion protection efficacy of multilayer coatings was found to be decreased at high degree of layering due to diffusion of layers. Improved corrosion resistance of multilayer Sn-Ni coatings is attributed to an increase in the number of layers, or interfaces separating alloys of the same metals, but of different composition, surface morphologies and phase structures, supported by energy dispersive spectroscopy, field emission scanning electron microscopy and X-ray diffraction study, respectively. The better corrosion protection of CMMA Sn-Ni coatings, compared to monolayer counterparts, is attributed to an increase in the number of layers, hence phase boundaries between layers, and experimental results are discussed. © 2018 The Royal Society of Chemistry.
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    Novel RGO-ZnWO4-Fe3O4 nanocomposite as an efficient catalyst for rapid reduction of 4-nitrophenol to 4-aminophenol
    (American Chemical Society service@acs.org, 2016) Mohamed, M.J.; Bhat Denthaje, K.
    We report herein a simple, economic, and facile approach for the synthesis of a novel reduced graphene oxide-zinc tungstate-iron oxide (RGO-ZnWO4-Fe3O4) nanocomposite by a one-pot microwave method and its efficiency as a catalyst in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride (NaBH4). The as-prepared RGO-ZnWO4-Fe3O4 nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The prepared nanocomposites showed excellent catalytic performance in the reduction of 4-NP to 4-AP. The reaction was completed in just 40 s at room temperature. The RGO in RGO-ZnWO4-Fe3O4 nanocomposite plays an essential role to improve the catalytic performance through facilitation of easy electron transfer and high adsorption of the substrate on graphene sheets. The synergistic effects of RGO, ZnWO4, and Fe3O4 in the RGO-ZnWO4-Fe3O4 nanocomposite toward reduction, apart from its excellent stability and reusability, make it an efficient candidate as catalyst for hydrogenation reactions of aromatic compounds in research and industrial applications. © 2016 American Chemical Society.