Faculty Publications
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Item Electrolytic Synthesis and Characterization of Electrocatalytic Ni-W Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2015) Elias, L.; Scott, K.; Hegde, A.Inspired by the more positive (about 0.38 V nobler) discharge potential of hydrogen on Ni-W alloy compared to that on both Ni and W, a Ni-W alloy has been developed electrolytically as an efficient electrode material for water electrolysis. The deposition conditions, for peak performance of the electrodeposits for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH medium have been optimized. Electrocatalytic activity of the coatings, deposited at different current densities (c.d.’s) for water splitting reactions of HER and OER was tested by cyclic voltammetry and chronopotentiometry. It was found that Ni-W alloys deposited, at 4.0 A/dm2 (having about 12.49 wt.% W) and 1.0 A/dm2 (having about 0.95 wt.% W) are good electrode materials as cathode (for HER) and anode (for OER), respectively. A dependency of the electrocatalytic activity for HER and OER with relative amount of Ni and W, in the deposit was found. The variation of electrocatalytic activity with W content showed the existence of a synergism between high-catalytic property of W (due to low hydrogen overvoltage) and Ni (having increased adsorption of OH? ions), for hydrogen (as cathode) and oxygen (as anode) evolution, respectively. Electrocatalytic activities of the coatings, developed at different c.d.’s were explained in the light of their phase structure, surface morphology, and chemical composition, confirmed by XRD, FESEM, and EDX analysis. The effect of c.d. on thickness, hardness, composition, HER, and OER was analyzed, and results were discussed with possible mechanisms. © 2015, ASM International.Item Modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticles(Royal Society of Chemistry, 2016) Elias, L.; Hegde, A.This work reports the modification of Ni-P alloy coatings for better hydrogen production by electrochemical dissolution and TiO2 nanoparticle incorporation. The first part is devoted to optimization of a new citrate bath for the development of an efficient electroactive Ni-P electrode material by electrodeposition, using glycerol as an additive. The Ni-P alloys developed at 4.0 A dm-2 and 2.0 A dm-2 were found to be good for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively as demonstrated by cyclic voltammetry (CV) and chronopotentiometry (CP) methods. The Ni-P alloy showing good catalytic activity for HER is found to be less active for OER and vice versa. The unique electrocatalytic property of the coatings was attributed to its structure, morphology and composition, confirmed by XRD, SEM and EDS analyses. In the second part, the electrocatalytic activity of Ni-P alloy coatings for HER has been improved further by anodic dissolution and TiO2 nanoparticle incorporation. Drastic improvement in the electrocatalytic activity for HER was found in both anodically treated and Ni-P-TiO2 composite coatings, compared to as-coated Ni-P alloys. The highest electrocatalytic character of the Ni-P-TiO2 composite coating was attributed to a greater number of electroactive centres, affected by TiO2 nanoparticle incorporation, and experimental results are discussed. © The Royal Society of Chemistry 2016.Item Magnetoelectrodeposition of Ni-W alloy coatings for enhanced hydrogen evolution reaction(Royal Society of Chemistry, 2016) Elias, L.; Cao, P.; Hegde, A.The electrocatalytic efficiency of electrodeposited (ED) Ni-W alloy coatings for the hydrogen evolution reaction (HER) has been improved drastically through magnetoelectrodeposition (MED) approach. Ni-W alloy coatings have been developed under different conditions of magnetic field intensity 'B' (applied perpendicular in the range of 0.1-0.4 T), and their electrocatalytic activity for the HER has been tested using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques in 1.0 M KOH solution. A drastic improvement in the electrocatalytic behavior of the MED coating, represented as (Ni-W)B=0.2 T was found as compared to its conventional Ni-W alloy coatings. Improved performance of the MED coatings was explained on the basis of differences in the process of electrocrystallization affected due to the applied magnetic field, supported by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. A magnetic field has been used advantageously for the first time to increase the W content of the alloy. Increased activity of the MED coatings was attributed to the increased W content in the alloy, characterized by the unique (220) reflection, explained by the magnetohydrodynamic (MHD) effect due to Lorentz force. © 2016 The Royal Society of Chemistry.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 Nano-composites of NiFe-LDH/V Se2 heterostructures for effective water splitting electrocatalyst(Elsevier Ltd, 2024) Hegde, A.; Mukesh, P.; G, L.S.; Kumar, A.; Nagaraja, H.S.In the realm of sustainable and environmentally friendly “green-hydrogen” fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their durability In the realm of sustainable and environmentally friendly “green-hydrogen” fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their performance and durability in corrosive alkaline water at high current density remain limited. In this regard, one can make the nano-composites of this NiFe-LDH with high electronic conductivity materials and layered structures like VSe2. With this motivation, this work presents a novel electrocatalyst, NiFe-LDH, supported with VSe2 nanosheets (V Se2/NiFe−LDH), designed to address these challenges and enhance water splitting efficiency. Experimental results demonstrate that the heterostructure synergistically reduces charge transfer resistance, increases exposure of active sites, and enhances oxygen gas evolution ability. Consequently, the V Se2/NiFe−LDH electrocatalyst demonstrated superior sustainability, maintaining an elevated current density (500mAcm−2) for over 50 h of continuous electrolysis without noticeable degradation. This research opens up new possibilities and shows that nano-compositing can be a good option for achieving efficient and durable electrocatalysts in alkaline water splitting, thereby contributing to sustainable hydrogen production. © 2024 Hydrogen Energy Publications LLC