Faculty Publications
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Item Calcium copper titanate a perovskite oxide structure: effect of fabrication techniques and doping on electrical properties—a review(Springer, 2022) Infantiya, S.G.; Aslinjensipriya, A.; Reena, R.S.; Deepapriya, S.; Rodney, J.D.; Jerome das, S.J.; Justin Raj, C.J.The discovery of innovative multifunctional ceramics is an important topic in the recent field of research and development. Perovskite oxide ceramics exhibit a wide range of multifunctional characteristics, such as ferromagnetism, ferro-, piezo-, and pyro-electricity and nonlinear dielectric properties. These characteristics are significant for use in environmental remediation, sensors, filters, energy conversion, and storage, corrosion-resistance coatings, aerospace industries, separators, detectors, antennas, etc. The calcium copper titanate (CCTO) with colossal dielectric constant with low dielectric loss tangent, and its isomorphs have piqued the interest of the development of advanced capacitor materials for electronic industries. CaCu3Ti4O12 (CCTO) exhibits the most extraordinary characteristic, with a dielectric permittivity at 1 kHz of ~ 104 that is essentially constant from ambient temperature to 300 °C. The substitution of metal cations/anions is an effective strategy to enhance the properties of the CCTO ceramics and extend their applications. In this review, we systematically examined the advancements of CCTO ceramics, including their structural morphology, tolerance factor, extrinsic/intrinsic mechanisms, different synthesis techniques, sintering techniques, and the effect of single doping as well as the co-doping mechanism for the enhancement of the dielectric and electrical properties. A series of CCTO-based ceramics have been summarized and explained their mechanisms and electrical properties. We anticipate that our study will help as an overview and motivate other researchers to continue working on the fabrication of CCTO or other electro-ceramics in the upcoming years. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.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 New hybrid semiconducting CdSe and Fe doped CdSe quantum dots based electrochemical capacitors(Elsevier Ltd, 2022) Premanand, G.; Sridevi, D.V.; Perumal, S.; Maiyalagan, T.; Rodney, J.D.; Ramesh, V.In this study, pure and Fe-doped CdSe (Fe@CdSe) quantum dots (QDs) in various concentrations have been prepared via the chemical co-precipitation method. The PXRD, FT-IR, UV–vis spectroscopy, and HR-TEM micrographs have been utilized to confirm the structural, optical, and morphological features of as-synthesized QDs. The optical bandgap values of pure and Fe@CdSe QDs have been found to vary from 2.12 eV to 1.82 eV, as determined by the Tauc relation, and the absorption spectrum of pure and Fe@CdSe QDs exhibits a blue shift compared to the bulk CdSe. Moreover, three-electrode configuration systems have been employed to characterize the electrochemical properties of pure and Fe@CdSe QDs. Notably, the areal capacitance of pure CdSe is 47 mFcm−2, which considerably increases to ∼73 mFcm−2 for 6 mol.% Fe@CdSe QDs QDs at a scan rate of 5 mVs−1. © 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 Bi-functional LaMxFe1-xO3 (M = Cu, Co, Ni) for photo-fenton degradation of methylene blue and photoelectrochemical water splitting(Elsevier Ltd, 2023) James, A.; Rodney, J.D.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.Due to growing concern over environmental remediation and the energy crisis, perovskite nanoparticles have gained wide interest in converting solar energy to sustainable fuel and also in degrading organic effluents. Herein, we report the synthesis and bi-functional activity of one-pot-glycine combustion derived LaMxFe1-xO3 (M = Cu, Co, Ni; x = 0, 0.01) for photo-Fenton degradation of Methylene Blue (MB) and photoelectrochemical water splitting. When used as a photocatalyst, with partial substitution of Cu even at a lower concentration, LaCu0.01Fe0.99O3 has exhibited excellent degradation efficiency of 96.4% in 90 min, which is 2.5 times better than the LaFeO3. On the other hand, Co and Ni modified LaFeO3 photocatalysts have demonstrated prominent activities with degradation efficiency of 93.8% and 74.8% respectively within 180 min of visible light irradiation. The retention and reusability analysis showed that LaCu0.01Fe0.99O3 is stable against photo corrosion and remains unchanged after 5 consecutive cycles of MB dye degradation. In addition, LaCu0.01Fe0.99O3 is complimented as a single catalyst for dual functions such as photocatalysis and electrocatalysis, both of which are assisted by visible light. Under illumination, the overpotential (η) improved from 507.6 mV vs RHE (dark) to 498.1 mV vs RHE (light) for O2 evolution and 220.5 mV vs RHE (dark) to 182.8 mV vs RHE (light) for H2 generation respectively. The light response of the catalyst and improvement in activity is validated by the significant enhancement in current density under exposure at both half cycle of chronoamperometry. © 2023 Hydrogen Energy Publications LLCItem A novel effective immobilization of glucose oxidase on Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 – Chitosan nanocomposite as an enzymatic glucose biosensor(Elsevier B.V., 2023) Deepapriya, S.; Rodney, J.D.; John, J.; Joshi, S.; Udayashankar, N.K.; Lakshmi Devi, S.; Jerome das, S.An effectual enzymatic glucose biosensor has drawn significant attention in the natural world due to its continuous glucose monitoring systems on human beings. A need for accurate and dependable glucose biosensors is needed and has notably augmented the keen interest to synthesize new non-invasive glucose monitoring systems in the recent phase. A novel Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 nanocomposite has been synthesized via the combustion method to develop an appreciable glucose biosensor. The glucose biosensor was fabricated by immobilization of glucose oxidase (GOx) onto chitosan (CH)-Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 heterojunction nanocomposite on FTO glass substrate. The performance of the as-prepared enzymatic glucose biosensor was estimated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical studies revealed an enhanced diffusion of molecules on the electrode surface, superior charge transfer rate, high sensitivity, and fast response time. The Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4-CH bi-junction conjoining with GOx exhibits a higher sensitivity of 52.76 µAmM-1cm−2 in a comprehensive undeviating range. The catalytic properties of the electrode in the H2O2 solution were studied using cyclic voltammetry, which showed a good linear response with an increase in scan rate and peak current resulting in enriched electrostatic interaction. In addition, the fabricated biosensor with a low Michaelis-Menten constant contributes a better affinity of the electrode surface towards glucose oxide. © 2023 Elsevier B.V.Item Structural, dielectric and impedance functionalities of La0.01Cu0.99O nanocrystals(Springer, 2023) Deepapriya, S.; Rodney, J.D.; Udayashankar, N.K.The necessity for materials designed with high and low-K dielectric constant having unique thermal stability has been a prime factor for the continuous development of the microelectronics-based industries. To address this issue, pure and 1% lanthanum (La) substituted copper oxide (CuO) nanoparticles were synthesized through an eco-friendly and time effective co-precipitation route for new unanticipated facts. The thermal effisivity of the material was determined by means of photoacoustic spectroscopy (PAS). The dielectric analysis of the monoclinic structured pure and La doped CuO nanoparticles in the frequency range of 1 Hz–1 MHz for various temperatures was noted, Dielectric constant and loss factor had a declining trend with surge in applied frequency and turned out to be independent of frequency at higher frequencies. The AC conductivity observed has confirmed the semi-conducting nature of the nanoparticle and obeyed Jonscher’s universal law. The temperature-dependant electric relaxation process was revealed using complex impedance spectroscopic studies suggesting non-Debye type behaviour of the material. The electrical activity of the nanoparticles is established for the circuit model devised from the calculated relaxation time constant. The impact of the thermal property and the hopping mechanism in the material with indices of interest is confirmed from the electric modulus. The obtained impedance spectra indicate the effect of lanthanum on the grain boundaries and the higher basicity and electropositive nature of lanthanum on the dielectric relaxation process. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Revolutionizing energy storage: A novel Cu2Se-GO nanocomposite for supercapacitors(Elsevier B.V., 2023) Mascarenhas, F.J.; Rodney, J.D.; Mishra, P.; Badekai Ramachandra, B.R.There is a requirement for the evolution of clean energy sources since the energy demand has exponentially increased. Therefore, substantial research is being implemented to efficiently convert renewable energy and capture it in energy storage devices. In this regard, fabricating unique, advanced, and potent supercapacitor materials has been laborious and demanding. Herein, we report a facile one-pot hydrothermal method for synthesizing copper selenide (Cu2Se)-graphene oxide (GO) nanocomposite. Among the various compositions developed, Cu2Se-5GO showed the highest specific capacitance of 219 F/g at 5 mV/s when used as an electrode material in a 2 M KOH solution. Also, the composition showed a capacitance retention of 90.6 % after 10,000 charge–discharge cycles. Therefore, the collective effect of copper selenide and graphene oxide has proved the material to be upsurging, accessible, and utilizable for prospective electrochemical energy storage devices. © 2023 Elsevier B.V.Item 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.
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