Faculty Publications
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Item Enhanced photoelectrochemical water splitting behaviour of tuned band gap CdSe QDs sensitized LaB6(American Scientific Publishers, 2017) Babu, M.S.; Sivanantham, A.; Chakravarthi, B.B.; Kannan, R.S.; Panda, S.K.; Berchmans, L.J.; Arya, S.B.; Sreedhar, G.We report the fabrication of tuned band gap quantum dots sensitized LaB6 hybrid nanostructures and their application as a photoanode for photoelectrochemical water splitting. The lanthanum hexaboride (LaB6) obtained by molten salt electrolysis method is sensitized with different sized CdSe quantum dots, which form a multiple-level hierarchical heterostructure and such design enhance the light absorption and charge carrier separation, which in turn showed higher photocurrent density compared to that of pristine LaB6. When LaB6 is sensitized with CdSe quantum dots of different band gaps, which have the absorption in the green and red (530 and 605 nm) regions in visible light, developed a ten times higher photocurrent density (11.0 mA cm-2) compared to that of pristine LaB6 (0.5 mA cm-2 at 0.75 V vs. Ag/AgCl) in 1 M Na2S electrolyte under illumination. These results prove that the tuned band gap quantum dots sensitized LaB6 heterostructures are an ideal candidate for a photoanode in solar water splitting applications. © © 2017 American Scientific Publishers All rights reserved.Item Electrodeposition and characterization of Ni-Mo alloy as an electrocatalyst for alkaline water electrolysis(Elsevier B.V., 2017) Shetty, S.; Mohamed, M.; Bhat, D.K.; Hegde, A.C.This work details the efficiency of Ni-Mo alloy as an electrode for water splitting application through electrodeposition method. Nano-crystalline Ni-Mo alloy coatings were deposited in the current density (c.d.) range of 1.0–4.0 A dm? 2 on a copper substrate, and were investigated for their deposit characters, and their electrocatalytic behaviours in 1.0 M KOH solution. The electrocatalytic behaviour of the coatings, in terms of their hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), were evaluated by electrochemical methods, like cyclic voltammetry (CV) and chronopotentiometry (CP). Experimental results revealed that Ni-Mo alloy electrodeposited at 1.0 A dm? 2 (38.3 wt% Mo) and 4.0 A dm? 2 (33.2 wt% Mo) shows the highest electrocatalytic tendency for HER and OER, respectively. The corrosion behaviour of Ni-Mo alloy coated at 4.0 A dm? 2 is found to be the most corrosion resistant in the same alkaline medium, compared to other coatings. The highest electrocatalytic activity of Ni-Mo alloy deposit for both HER and OER, depending on deposition c.d. was attributed to their composition (in terms of Ni and Mo content), structure and surface morphology; supported by EDXA, XRD, SEM and AFM analyses. The experimental study demonstrated that Ni-Mo alloy coatings follow Volmer-Tafel type of mechanism for HER, testified by Tafel slope analyses. © 2017 Elsevier B.V.Item Chemically prepared Polypyrrole/ZnWO 4 nanocomposite electrodes for electrocatalytic water splitting(Elsevier Ltd, 2019) Brijesh, K.; Bindu, K.; Shanbhag, D.; Nagaraja, H.S.ZnWO 4 , PPy, and PPy/ZnWO 4 nanoparticles were prepared using chemical synthesis. The structural, compositional and morphological properties of the prepared samples have been investigated using XRD, FTIR, SEM, and HRTEM respectively. The powder XRD reveals the monoclinic wolframite structure for both ZnWO 4 and PPy/ZnWO 4 nanocomposite. SEM confirms the wrapping of ZnWO 4 with PPy. The electrodes of ZnWO 4 , PPy, and PPy/ZnWO 4 have been tested as bifunctional electrocatalyst towards HER and OER using constant current chronopotentiometry (CP) and Linear Sweep Voltammetry (LSV). The electrochemical surface area and the electrocatalytic activity PPy/ZnWO 4 nanocomposite towards HER and OER are greater than that of pure ZnWO 4 and PPy. The Tafel slope of PPy/ZnWO 4 nanocomposite is 76 and 84 mV dec ?1 in 0.5 M H 2 SO 4 and 1 M KOH at room temperature for HER and OER respectively. The results suggest that PPy/ZnWO 4 nanocomposite is a good candidate for the bifunctional electrocatalyst for water splitting. © 2018 Hydrogen Energy Publications LLCItem 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 annealing temperature on the bifunctional electrocatalytic properties of strontium nickelate (SrNiO3) nanoparticles for efficient overall water splitting(Elsevier Ltd, 2022) J, J.; Jayalakshmi, J.; Rodney, J.D.The global trend in energy demand has paved way for clean hydrogen (H2) energy production at large scale. To address this issue, perovskite (ABX3) nanomaterials are widely researched to replace the noble metal electrocatalysts for electrochemical water splitting. In this work, the effect of annealing temperature on the structural and electrochemical properties of combustion derived strontium nickelate (SrNiO3) nanoparticles are studied. Benefitting from the unique features of perovskites, SrNiO3 nanoparticles displays excellent OER and HER activity in 1.0 M KOH with an overpotential of 259 mV and 451 mV to achieve 10 mAcm−2 respectively. SrNiO3 nanoparticles show superior HER activity when annealed at higher temperature and subtle change in OER activity. The stability of SrNiO3 nanoparticles were noteworthy as it shows no degradation even after 12 h. The overall water splitting of highly active SrNiO3 nanoparticles was carried out in a two-electrode system and the setup posted a cell voltage of 1.88 V at 10 mAcm−2 after continuous water splitting for 24 h. Thus, SrNiO3 nanoparticles may possibly serve as a potential bifunctional electrocatalyst for H2 production. © 2022 Hydrogen Energy Publications LLCItem Boosting overall electrochemical water splitting via rare earth doped cupric oxide nanoparticles obtained by co-precipitation technique(Elsevier Ltd, 2022) Rodney, J.D.; Deepapriya, S.; Jerome das, S.J.; Robinson, M.C.; Perumal, S.; Sadhana, S.; Periyasamy, P.; Jung, H.; Justin Raj, C.J.The development of electrocatalyst based on nonprecious metals has been a persistent issue as electrochemical water splitting requires electrocatalyst with advanced activity and stability. Further, the electrocatalyst must require low overpotential above the standard potential (>1.23 V) of water splitting to produce hydrogen. This study presents the facile co-precipitation derived rare earth dysprosium (Dy) doped cupric oxide nanoparticles (Cu1−xDyxO) as a non-noble transition metal oxide nanoparticle. The 3 % Dy doped CuO (3 % Dy/CuO) and 1 % Dy doped CuO (1 % Dy/CuO) electrocatalysts showed excellent Oxygen Evolution Reaction (OER) at 1.55 V vs RHE and Hydrogen Evolution Reaction (HER) at − 0.036 V vs RHE in aqueous 1 M KOH aqueous electrolyte to attain the benchmark current density (10 mA cm−2). The stability of the driven electrocatalyst in a bi-functional electrocatalytic setup was monitored for 24 h and was found to be exhibiting a cell voltage of about 2.1 V at 30 mA cm−2 constant current density. Further, the retention capability of the electrode was observed to be 99 % with a very minimal loss. This study hugely suggests the promising consequence of doping rare earth onto a non-precious metal oxide-based electrocatalyst, making it a highly effective bifunctional material for water splitting. © 2022 Elsevier B.V.Item Combustion-derived BaNiO3 nanoparticles as a potential bifunctional electrocatalyst for overall water splitting(Elsevier Ltd, 2023) J, J.; Jayalakshmi, D.; Rodney, J.D.Electrochemical water electrolyser though an assuring solution for clean hydrogen production, the sluggish kinetics and high cost of existing precious metal electrocatalyst remains a barrier to its effective utilization. Herein, solution combustion route derived perovskite type barium nickelate (BaNiO3) nanoparticles were developed and studied for their bifunctional electrocatalytic properties towards overall water splitting. The unannealed BaNiO3 nanoparticles exhibited the highest OER and HER activity with overpotentials 253 mV and 427 mV respectively to attain 10 mAcm−2 in 1.0 M KOH. Using unannealed BaNiO3 as a bifunctional electrocatalyst in a two-electrode alkaline electrolyser, the cell was able to achieve the benchmark current density at a low cell voltage of 1.82 V. Impressively the setup's electrocatalytic performance improved 4.9% after continuous overall water splitting for 24 h at 30 mAcm−2. Therefore, BaNiO3 nanoparticles can be a low-cost and efficient alternative for noble metal electrocatalysts for clean H2 production. © 2022 Hydrogen Energy Publications LLCItem Cobalt-doped LaFeO3 for photo-Fenton degradation of organic pollutants and visible-light-assisted water splitting(Springer, 2024) James, A.; Rodney, J.D.; Manojbabu, A.; Joshi, S.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.The increasing demand for clean energy sources and the growing concerns about environmental pollution have led to a significant interest in developing efficient photocatalytic and photoelectrochemical systems. Here, we report the visible-light-induced photo-Fenton catalytic degradation of Methylene Blue (MB) dye over LaFeO3 and LaCo xFe1−xO3 (x = 0.01, 0.05, 0.1) catalysts synthesized via the facile combustion method. The LaCo0.01Fe0.99O3 has significantly enhanced the photo-Fenton catalytic efficiency of LaFeO3 from 67.75 to 93.85% for MB dye removal after 180 min of light irradiation. The rate constants calculated via the pseudo-first-order kinetics mechanism are found to be 0.00532/min for LaFeO3 and 0.01476/min for LaCo0.01Fe0.99O3, respectively. In addition, the most effective LaCo0.01Fe0.99O3 catalyst has demonstrated remarkable degradation performance towards Tetracycline (TC) and Methyl Orange (MO) dye with an efficacy of 93.81% and 69.67%, respectively, indicating its versatility. Further, the pristine and doped LaFeO3 were structurally optimized using DFT, and the computed band gaps were following the experimental data. Interestingly, the same catalyst can be employed as a light-induced electrocatalyst in addition to water treatment by taking advantage of its dual functionality. The LaCo0.01Fe0.99O3 catalyst achieved a benchmark current density of 10 mA/cm2 for H2 evolution at an overpotential of 297 mV vs. RHE which further improved to 190 mV vs. RHE under illumination. This work provides valuable insights on partial Co incorporation at the B-site of LaFeO3 for the development of visible-light-induced photocatalytic and electrocatalytic systems, which is hoped to contribute to the advancement of sustainable energy production and environmental remediation. © 2024, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item 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 LLCItem Growth of octahedral structured AgBiS2 single crystals and its insights on the high performance electrocatalytic hydrogen generation(Elsevier Ltd, 2024) Jauhar, R.O.M.; Ramachandran, K.; Deepapriya, S.; Joshi, S.; Ghfar, A.A.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.; Vadivel, V.; Raji, R.; Kim, B.C.; Rodney, J.D.Given the enormous depletion of fossil fuels and growing environmental concerns, there is an immediate need to develop alternative and clean energy sources. Hydrogen (H2), recognized for its cleanliness and renewability, is poised to meet future energy requirements. Consequently, ongoing research is focused on the development of electro-active, durable, and cost-effective catalysts to replace expensive noble metal-based electrocatalysts. In this study, microscale AgBiS2 chalcogenide derived from a single crystal is reported as promising electrocatalysts for the Hydrogen Evolution Reaction (HER) with a remarkably low overpotential. The physico-chemical characterization of the AgBiS2 catalyst has been investigated using various analytical techniques. The synthesized AgBiS2 catalyst exhibits excellent HER activity, manifesting a low overpotential of 86 mV at a current density of 10 mA cm−2 and a Tafel slope of 44 mV dec−1, along with superior stability even after 24 h in HER at a very high current density. The developed AgBiS2 also showcased stable production when subjected to a two-electrode system. The enhanced alkaline HER activity of AgBiS2 can be attributed to its phase purity, high crystallinity, and the presence of high active sites. The observed high electrochemical performance and stability position AgBiS2 as a potential electrocatalyst for the hydrogen evolution reaction. This finding holds significant promise in the quest for efficient, durable, and economically viable catalysts to drive the shift towards clean and renewable energy sources. © 2024 Hydrogen Energy Publications LLC