Faculty Publications
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Item Electrodeposition of Ni-Mo alloy coatings for water splitting reaction(American Institute of Physics Inc. subs@aip.org, 2018) Shetty, A.R.; Hegde, A.C.The present study reports the development of Ni-Mo alloy coatings for water splitting applications, using a citrate bath the inducing effect of Mo (reluctant metal) on electrodeposition, its relationship with their electrocatalytic efficiency were studied. The alkaline water splitting efficiency of Ni-Mo alloy coatings, for both hydrogen evolution reaction (HER) and oxygen evolution reaction were tested using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. Moreover, the practical utility of these electrode materials were evaluated by measuring the amount of H2 and O2 gas evolved. The variation in electrocatalytic activity with composition, structure, and morphology of the coatings were examined using XRD, SEM, and EDS analyses. The experimental results showed that Ni-Mo alloy coating is the best electrode material for alkaline HER and OER reactions, at lower and higher deposition current densities (c. d.'s) respectively. This behavior is attributed by decreased Mo and increased Ni content of the alloy coating and the number of electroactive centers. © 2018 Author(s).Item Ultrasound induced multilayer Ni-Co alloy coatings for better corrosion protection(Elsevier B.V., 2017) Shetty, A.R.; Hegde, A.Ultrasound induced multilayer Ni-Co alloy coatings have been developed galvanostatically by periodic modulation of ultrasound effect, parallel to the process of conventional electroplating. Multilayer Ni-Co alloy having alternative layers of different composition were developed by turning the sonicator probe, ON and OFF periodically, while keeping the current density (c.d.) constant. The deposition conditions, in terms of pulsing power density (p.d.) and degree of layering have been optimized for the highest performance of coating against corrosion, evaluated by electrochemical testing methods. Corrosion data revealed that under optimal conditions, multilayer Ni-Co alloy coating having 150 layers, represented as (Ni-Co)2/2/150 is about 11 times more corrosion resistant than its homogeneous coating, represented as (Ni-Co)4.0 A dm ? 2, deposited from the same bath for same duration of time. Improved corrosion resistance of multilayer Ni-Co alloy coatings was attributed to an increase in the number of interfaces, separating the layers of alloys of different composition, affected due to periodic pulsing of the sonicator. The dependence of corrosion behaviors at different combination of c.d. and p.d., on surface morphology, composition and phase structures were analyzed, using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD) technique, respectively. Experimental results are compared, and discussed. © 2017 Elsevier B.V.Item Effect of TiO2 on electrocatalytic behavior of Ni-Mo alloy coating for hydrogen energy(KeAi Communications Co., 2018) Shetty, A.R.; Hegde, A.Ni-Mo-TiO2 composite coating has been developed through electrodeposition method by depositing titanium dioxide (TiO2) nanoparticles parallel to the process of Ni-Mo alloy coating. The experimental results explaining the increased electrocatalytic activity of Ni-Mo alloy coating on incorporation of TiO2 nanoparticles into its alloy matrix is reported here. The effect of addition of TiO2 on composition, morphology and phase structure of TiO2 – composite coating is studied with special emphasis on its electrocatalytic activity for hydrogen evolution reaction (HER) in 1.0 M KOH solution. The electrocatalytic activity of alloy coatings were validated using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. Under optimal condition, TiO2 – composite alloy coating represented as (Ni-Mo-TiO2)2.0 A dm?2 is found to exhibit the highest electrocatalytic activity for HER compared to its binary alloy counterpart. The increased electrocatalytic activity of (Ni-Mo-TiO2)2.0 A dm?2 composite coating was attributed to the increased Mo content, porosity and roughness of coating, affected due to addition of TiO2 nanoparticles, supported by SEM, EDX, XRD and AFM study. The increased electrocatalytic activity of (Ni-Mo-TiO2)2.0 A dm?2 coating was found due to decreased Rct and increased Cdl values, demonstrated by EIS study. Better electrocatalytic activity of (Ni-Mo-TiO2)2.0 A dm?2 coating, compared to (Ni-Mo)2.0 A dm?2 coating has been explained through mechanism. Experimental study revealed that (Ni-Mo-TiO2)2.0 A dm?2 composite coating follows Volmer-Heyrovsky mechanism, compared to Tafel mechanism in case of (Ni-Mo-TiO2)2.0 A dm?2 coating, assessed on the basis of Tafel slopes. © 2018Item Polymorph nickel titanate nanofibers as bifunctional electrocatalysts towards hydrogen and oxygen evolution reactions(Royal Society of Chemistry, 2019) Kumar, B.; Tarafder, K.; Shetty, A.R.; Hegde, A.C.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.Producing pure H2 and O2 to sustain the renewable energy sources with minimal environmental damage is a key objective of photo/electrochemical water-splitting research. Metallic Ni-based electrocatalysts are expensive and eco-hazardous. This has rendered the replacement or reduction of Ni content in Ni-based electrocatalysts a decisive criterion in the development of bifunctional electrocatalytic materials. In the current study, spinel/ilmenite composite nickel titanate (NTO) nanofibers were synthesised using sol-gel assisted electrospinning followed by pyrolysis at different soaking temperatures (viz., 773, 973, and 1173 K). The presence of a defective spinel NTO phase (SNTO) distributed uniformly along the nanofibers was confirmed by X-ray photoelectron and Raman spectroscopy. The electron micrographs revealed the morphological change of NTO nanofibers from a mosaic to bamboo structure with an increase in pyrolysis soaking temperature. The electrocatalytic activity of NTO nanofibers obtained at different pyrolysis soaking temperatures for alkaline water-splitting was studied. The highly defective SNTO manifests properties similar to metallic Ni and favours H2 evolution through the hydrogen evolution reaction (HER) by adsorbing more H+ ions on active sites. In contrast, the ilmenite NTO favours O2 discharge. These results are explained based on the morphology of the NTO nanofibers. The mosaic structure which has higher porosity and greater SNTO content shows excellent HER performance. In contrast, the large bamboo structured NTO nanofibers which have lesser porosity and SNTO content cage the bigger (OH)ads ions at their catalytic sites to facilitate OER performance. 2019 © The Royal Society of Chemistry.Item Sol-gel electrospun ZnMn2O4 nanofibers as bifunctional electrocatalysts for hydrogen and oxygen evolution reactions(Institute of Physics Publishing helen.craven@iop.org, 2019) Shamitha, C.; Shetty, A.R.; Hegde, A.C.; Anandhan, S.Electrochemical water-splitting has gained significant attention for the development of next generation fuels. The present work is an investigation on the electrocatalytic activity towards both Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER) of ZnMn2O4 (ZMO) nanofabrics synthesized by sol-gel electrospinning followed by calcination (at 500, 600 and 700 °C). Poly(styrene-co-acrylonitrile) was used as the polymeric binder for the production of nanofabrics. The morphological features of ZMO nanofabrics were studied by scanning electron microscopy and field emission scanning electron microscopy. The electrocatalytic behavior of ZMO nanofabrics obtained at different calcination temperatures was evaluated using chrono-potentiometry, cyclic voltammetry, and linear sweep voltammetry in an alkaline medium (1 M KOH). The ZMO nanofabrics calcined at 500 °C exhibited the maximum electrocatalytic activity towards HER. This can be ascribed to their superior specific surface area (79.5 m2 g-1). The nanofabrics calcined at 700 °C displayed the least potential for O2 evolution and hence they are considered to be effective for OER. The results prove that ZMO nanofabrics are promising candidates as bifunctional electrocatalysts for water-splitting applications. © 2019 IOP Publishing Ltd.Item Effect of Magnetic Field on Corrosion Performance of Ni–Co Alloy Coatings(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, A.R.; Hegde, A.C.The corrosion protection efficacy of Ni–Co alloy coatings was tried to improve by magnetoelectrodeposition (MED) approach. The magnetic field of varying strength (B) was applied in perpendicular and parallel to the direction of diffusion of metal ions, simultaneously to the process of deposition. The corrosion behaviour of the deposited coatings was studied through electrochemical DC method and results revealed that Magneto-electrodeposited (MED) Ni–Co alloys coatings were found to be more corrosion resistant than their conventionally electrodeposited (ED) counterparts. Moreover, the effect of magnetic field is more pronounced in perpendicular field direction and was explained by Lorentz force. Under optimal condition, MED Ni–Co alloy coating obtained at a magnetic field intensity of B = 0.3 T (Perpendicular) was found to be less prone to corrosion than its ED alloy (B = 0 T) counterpart. The increased limiting current density (iL) of Co2+ ions in turn increases the corrosion resistant properties of MED Ni–Co alloy coatings. The effect of magnetic field on improved corrosion resistance of the deposited coatings have been investigated in terms of their changed surface morphology, composition, phase structure and surface roughness using Scanning electron microscopy (SEM), Energy dispersion spectroscopy (EDS), X-Ray diffraction (XRD) technique and Atomic Force Microscopy (AFM) respectively. © 2022, The Author(s).Item Effect of limiting current density on corrosion performance of Ni–Mo, Ni–Cd and Ni–Mo–Cd alloy coatings(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, A.R.; Hegde, A.C.In this article an attempt was made to increase the corrosion resistance of Ni–Mo alloy coatings with the addition of small quantity of CdCl2 into its bath. The limiting of limiting current density (iL) of Ni in both Ni–Mo and Ni–Cd baths due to inherent induced and normal type of codeposition has been successfully alleviated by addition of 1 g/L of CdCl2. The advent of induced and normal type of codeposition of individual binary baths has been used to optimize the Ni content of the ternary deposit for better corrosion stability. The composition vs. current density plots of all coatings have been studied, and thereby optimal iL of Ni in all baths were assessed. The content of Mo was found to be decreased with the small addition of Cd to the bath. Results revealed that (Ni–Mo–Cd)6.0 Adm−2 coating showed better corrosion resistance by reducing iL of Ni, on addition of Cd+2 ions into the bath and was explained in the light of diffusion limited deposition of Ni+2 ions. The results were supported by SEM (scanning electron microscopy), XRD (X-ray diffraction) and AFM (atomic force microscopy) study of Ni–Mo, Ni–Cd and Ni–Mo–Cd coatings at optimal current densities. © 2023, The Author(s).Item Effect of square pulse current densities on anticorrosive behavior of Ni–Zn multilayer deposited coatings on mild steel(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, A.R.; Hegde, A.C.This paper reports the production of Ni–Zn multilayer alloy coating to improve the anticorrosive behavior of the mild steel material. The deposition technique follows the square wave current pulse technique. Initially, the effect of current densities on the anticorrosive behavior of the Ni–Zn was investigated. Later, the current densities were optimized in different combinations to get a multilayer of Ni–Zn with different degrees of layering. The Ni–Zn multilayer coatings were developed on the surface of mild steel with different numbers of layers by square pulsing current density of 1 Adm−2 and 3 Adm−2. The deposited Ni–Zn alloy coating was studied for its electrochemical behavior toward corrosion. Results revealed that the anticorrosive behavior of the multilayer Ni–Zn alloy coating was found to be many folds higher than that of monolayer Ni–Zn alloy coating. The comparison study of corrosion data revealed that (Ni–Zn)1/3/300 multilayer coatings are less prone to undergo corrosion among all developed monolayer and multilayer coatings. The corrosion rate of (Ni–Zn)1/3/300 was found to be less and in the range of 0.37 mm year−1 among all developed coatings. © 2023, The Author(s).Item Synthesis and characterization of Co-W alloy coatings for enhanced hydrogen evolution: effects of bath composition and deposition parameters(Taylor and Francis Ltd., 2025) Hegde, A.; Navada, M.K.; Ganesha, G.; Shetty, A.R.This study explores the development of Co-W alloy coatings as efficient electrode materials for the hydrogen evolution reaction (HER), offering new insights into their performance. Using a specially formulated electrolyte bath with glycerol as an additive, Co-W alloy coatings were deposited on copper under different [Co2+]/[WO42?] molar ratios. Their electrocatalytic efficiency was evaluated in 1 M KOH through cyclic voltammetry (CV), chronopotentiometry (CP), and hydrogen gas measurements using a custom glass device. The results showed that the combination of Co and W in the coatings significantly enhances performance, as confirmed by SEM, XRD, and EDS analyses. Potentiodynamic polarization studies further explained the HER mechanisms. This work introduces a unique bath composition and demonstrates how optimizing the alloy composition can improve HER activity, paving the way for better electrocatalysts. The study identified that the Co-W coating prepared using a 0.35 M solution at a current density of 1 Adm2 demonstrated the highest electrocatalytic efficiency. This performance was attributed to the tungsten content of approximately 30 wt% and the maximum hydrogen evolution observed under these optimized conditions. The hydrogen evolution reaction (HER) in Co-W alloys follows the Volmer-Heyrovsky mechanism, characterized by the rapid evolution of hydrogen. © 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of the University of Bahrain.