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Item Potential of pyrochlore structure materials in solid oxide fuel cell applications(Elsevier Ltd, 2021) Anjana, A.P.; Prasad Dasari, H.P.Pyrochlore structure material (A2B2O7) has gained interest in diverse applications like catalysis, nuclear waste encapsulation, sensors, and various electronic devices due to the unique crystal structure, electrical property, and thermal stability. This review deals with the ionic/electronic conductivity of numerous pyrochlore structure materials (titanates, zirconates, hafnates, stannates, niobates, ruthenates, and tantalite based pyrochlore) as electrolyte and electrode materials for solid oxide fuel cells (SOFCs). The impact of cation radius ratio (rA/rB) on the lattice constant and oxygen ‘x’ parameter of different pyrochlore structure materials obtained by various synthesis methods are reported. Higher ionic conductivity is essential for better ion transport in an electrolyte, and mixed ionic and electronic conductivity in electrode is essential for attaining higher efficiency in a typical SOFC. GdxTi2O7-δ, Gd2-xCaxTi2O7-δ, Nd2-yGdyZr2O7, Y2Zr2O7, Y2Zr2-xMnxO7-δ, SmDy1-xMgxZr2O7-x/2, Gd2-xCaxTi2O7-δ pyrochlore are reported as electrolytes for fuel cell applications. Some pyrochlore material (La2-xCaxZr2O7, Sm2-xMxTi2O7 (M = Mg, Co, and Ni) pyrochlore) shows protonic conductivity at lower temperatures and ionic conductivity at higher temperature condition. Also, the mixed ionic-electronic conductivity behavior is reported in electrode materials for SOFC such as R2MnTiO7 (R = Er and Y), R2MnRuO7 (R = Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), R2Ru2O7 (R = Bi, Pb and Y), Y2-xPrxRu2O7, Ni-(Gd0.9Ca0.1)2Ti2O7-δ, (Gd0.9Ca0.1)2Ti2O7-δ, Gd2(Ti0.8Ru0.2)2O7-δ, (Sm0.9Ca0.1)2Ti2O7-δ and (Y0.9Ca0.1)2Ti2O7-δ pyrochlore. The detailed study of the electronic behavior of these pyrochlore system confirms the necessity of defect structure with high oxygen mobility, lower activation energy, ionic radii ratio criterion should satisfy, and possess notable ion-ion interaction. Ionic conductivity in pyrochlore is increased by enhancing the oxygen migration through 48f-48f site with the formation of oxygen vacancy. Vacancy formation can be achieved by adding a suitable dopant that creates oxygen vacancy by charge compensation mechanism or as anion Frenkel defects. Similarly, the electrical conductivity is improved while adding suitable dopant (Ce, Pr, Ru, etc.) due to disordered structure and anti-Frenkel defect formation which leads to oxygen vacancy formation and thus improves conductivity. © 2020 Elsevier Ltd and Techna Group S.r.l.Item Ceria-based electrospun nanofibers and their widespread applications: A review(Academic Press, 2025) Prasad Dasari, H.P.; Patil, S.S.; Kamath, R.S.; Kisiela-Czajka, A.M.Electrospinning is a highly efficient technique for producing nanofibers, and it is noted for its cost-effectiveness, versatility, and user-friendly nature. The article evaluates the production of Ceria-based nanofibers primarily utilizing electrospinning technology and electrospinning parameters and explores their various potential applications. Ceria infused with lanthanoids and transition metals demonstrates significant potential as catalysts, optical sensors, and supercapacitors in various energy-related industrial applications. Their role as catalysts in water-gas and reverse water-gas shift reactions greatly enhances the water-splitting reaction in the Deacon process. Composite ceria nanofibers for wound therapy were developed by integrating polyurethane, cellulose acetate, and zein for biological applications. Soot-induced blockages in automobile filters pose challenges for the regeneration process of diesel particle filters, and the effectiveness of ceria-based nanofibers in soot and CO oxidation has been explored. Ce-based nanofibers produced via the electrospinning technique, with different operating parameters, exhibit notable variations in their morphology. Research indicates that, compared to traditional ceria, Ce-based nanofibers demonstrate greater surface area and porosity, a higher density of oxygen vacancies, and improved oxygen transfer efficiency, all essential for numerous redox and catalytic processes. The nanofibrous structure enhances electrical conductivity by expanding the surface area accessible for interaction with active components. The nanofibrous composite structure exhibits enhanced thermal and mechanical durability, making it appealing for numerous applications. © 2025 Elsevier LtdItem From non-renewable waste to activated carbon: A smart move towards sustainable development and environmental protection in a circular economy(Elsevier Ltd, 2025) Patil, S.S.; Kisiela-Czajka, A.M.; Prasad Dasari, H.P.Waste generation is unavoidable as the population grows and globalisation/modernisation occurs. Ineffective garbage management and treatment raise major environmental concerns. This study provides a comprehensive and unique compilation of available knowledge on the potential use of various non-renewable waste materials to produce activated carbon (AC). One document brings together and evaluates the potential for converting hazardous and non-hazardous waste – from industrial and municipal to recyclable and medical waste – into a valuable resource with wide-ranging applications. The appropriately selected conversion method is key to converting waste into a valuable activated carbon product. It must consider both the applicable legal regulations and the key technological parameters that determine the quality and suitability of the final product for a specific application. The numerous carbonisation and activation methods employed to convert waste to AC include hydrothermal, ionothermal, pyrolysis and microwave-assisted methods. AC's elemental composition and functional groups are analysed using elemental analysis, XPS and FTIR. Crystal structure and phase identification are performed via XRD, SEM and TEM. Surface area and porosity are determined using the BET and BJH methods, along with the iodine index. Following the thermal conversion of various waste materials into AC, it is widely used in multiple disciplines, including energy and the environment. AC is used as an adsorbent to effectively remove harmful elements from water, including pharmaceutical contamination, dyes and heavy metals. AC has excellent electrochemical characteristics and is highly efficient in CO2 capture. AC also extracts valuable products such as hydrocarbons, methane and uranium. © 2025 The Author(s)Item Record-low sintering-temperature (600 °c) of solid-oxide fuel cell electrolyte(Elsevier Ltd, 2016) Prasad Dasari, H.P.; Ahn, K.; Park, S.-Y.; Hong, J.; Kim, H.; Yoon, K.J.; Son, J.-W.; Kim, B.-K.; Lee, H.-W.; Lee, J.-H.One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 °C) to fully densify the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 °C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 °C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (?150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ?1.00 × 10-2 S cm-1 at 600 °C in air and from the conductivity plots the activation energy is found to be 0.53 eV. © 2016 Elsevier B.V. All rights reserved.Item Synthesis of GDC electrolyte material for IT-SOFCs using glucose & fructose and its characterization(Elsevier B.V., 2017) Medisetti, S.; Ahn, J.; Patil, S.; Goel, A.; Bangaru, Y.; Sabhahit, G.V.; Babu, G.U.B.; Lee, J.-H.; Prasad Dasari, H.P.Nano-powder of gadolinium-doped-ceria (GDC, Ce0.9Gd0.1O2) has been synthesized using a novel sol–gel method with glucose and fructose as organic additives. The main objective of the present study is to find the suitability of this synthesis method in synthesizing ceria-based SOFC electrolyte materials and evaluate its performance. The average crystallite/particle size obtained from XRD, TEM, BET surface area was found to be 4–12 nm. The phase was found to be cubic fluorite from XRD and further the structure and the nature of oxygen vacancies was confirmed using Raman spectroscopy. Dilatometer studies illustrated two shrinkage maxima (450 °C and 1450 °C). The ionic conductivity measurements were done using DC four-probe method on the GDC electrolyte sintered at 1500 °C. The sintered sample showed an ionic conductivity of 1.13E?02 Scm?1 at a temperature of 700 °C in the air, and the activation energy is 1.02 eV. The present study reveals that this synthesis method can be adaptable for synthesizing SOFC electrolyte materials. © 2017 Elsevier B.V.Item Soot Oxidation Activity of Redox and Non-Redox Metal Oxides Synthesised by EDTA–Citrate Method(Springer New York LLC barbara.b.bertram@gsk.com, 2017) Anjana, A.P.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Babu, G.U.B.Abstract: In the present study, redox (CeO2, SnO2, Pr6O11 and Mn3O4) and non-redox (Gd2O3, La2O3 ZrO2 and HfO2) metal oxides were successfully synthesised using the EDTA–citrate complexing method and tested for soot oxidation activity. The characterization of the metal oxides is carried out using FTIR, XRD, BET surface area, pore volume analyser, SEM and TEM. The redox nature and metal–oxygen bond information of the metal oxides are obtained from XPS analysis. In redox metal oxides, three critical parameters [lattice oxygen binding energy, reduction temperature and ?r (ionic size difference of the corresponding metal oxide oxidation states)] govern the soot oxidation activity. Among the redox metal oxide samples, Mn3O4 and Pr6O11 samples showed lower binding energy for oxygen (O?—529.4, 528.9 eV respectively), lower reduction temperature (T?—317 and 512 °C respectively) and have smaller ?r value (9 pm and 17 pm respectively). Thus, displayed a better soot oxidation activity (T50 = 484 and 482 °C respectively) than compared to other redox metal oxides. Among the non-redox metal oxides, HfO2 sample displayed higher BET surface area (21.06 m2/g), lattice strain (0.0157), smaller ionic radius (58.2 pm) and higher relative surface oxygen ratio (58%) and thus resulted in a significantly better soot oxidation activity (T50 = 483 °C) than compared to other non-redox metal oxides. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media, LLC.Item Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Geethu, J.; P, M.R.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Bhaskar Babu, G.U.Binary metal oxides of CeO2-Sm2O3 (CSx, x varies from 10 to 90 mol%) along with pure CeO2 and Sm2O3 were synthesised successfully by the EDTA-Citrate method. From XRD, Raman spectroscopy and UV–vis DRS results, the whole composition of metal oxides exist in three phases: (fluorite phase (F) (CS10-CS30), bi-phase (fluorite (F) + cubic (C)) (CS30-CS90) and cubic phase (C) (Sm2O3)). For CSx samples, the calculated band gap energy values obtained from the UV–vis DRS results were in between 3.0–5.1 eV and fluorite phase samples (CS10–CS30) displayed lower band gap energy values (3.04–3.07 eV) than compared to the samples in other phases. Similarly, from XPS analysis, fluorite phase samples (CS10–CS30) showed higher surface oxygen vacancy concentration than compared to samples in other phases. Catalytic activity for soot oxidation is carried out on CSx samples, and the T50 temperature is in between 480–540 °C. Fluorite phase samples (CS10 CS30) showed higher surface area, lower degree of agglomeration, lower band gap energy, higher oxygen vacancy concentration and better catalytic activity for soot oxidation. Among all the CSx samples, CS10 sample displayed highest surface area (38 m2/g), lowest degree of agglomeration (0.36), lowest band gap energy (3.04 eV), highest oxygen vacancy concentration (64%) and highest soot oxidation activity (T50 = 480 °C). The order of the soot oxidation activity of CSx samples followed the same trend of band gap energy values. © 2018 Elsevier B.V.Item Praseodymium doped ceria as electrolyte material for IT-SOFC applications(Elsevier Ltd, 2018) Shajahan, I.; Ahn, J.; Nair, P.; Medisetti, S.; Patil, S.; Niveditha, V.; Uday Bhaskar Babu, G.; Prasad Dasari, H.P.; Lee, J.-H.Praseodymium-doped ceria (PDC, Ce0.9Pr0.1O2) electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been successfully synthesised by EDTA-citrate method. From X-Ray diffraction (XRD), fluorite structure along with a crystallite size of 5.4 nm is obtained for PDC nanopowder calcined at 350 °C/24 h. Raman spectroscopy confirmed the structure, presence of oxygen vacancies with the manifestation of the main peak at 457 cm?1 and with a secondary peak at 550 cm?1. From Transmission Electron Microscopy (TEM) analysis, the average particle size is around 7–10 nm and selected area electron diffraction (SAED) patterns further confirmed the fluorite structure of PDC nanopowder. The PDC nanopowder displayed a BET surface area of 65 m2/g with a primary particle size of ?13 nm (calculated from BET surface area). Dilatometer studies revealed a multi-step shrinkage behaviour with the multiple peaks at 522, 1171 and 1461 °C which may be originated due to the presence of multiple size hard agglomerates. The PDC electrolyte pellet sintered at 1500 °C displayed an ionic conductivity of 1.213E-03 S cm?1 along with an activation energy of 1.28eV. Instead of a single fluorite structure, XRD of sintered PDC pellet showed multiple structures (Fluorite structure (CeO2) and cubic structure (PrO2). © 2018 Elsevier B.V.Item Surface morphology and phase stability effect of Ceria-Hafnia (CHx) binary metal oxides on soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.CeO2-HfO2 (CHx) binary metal oxides over whole composition range (0–100%) are synthesised using the EDTA-Citrate method and calcined at 600 °C/5 h. From XRD analysis, the sample series are classified as fluorite (F) phase for CH10-CH30, hybrid (F + M) phase for CH40-CH90 and monoclinic (M) phase for CH100 sample, respectively and the results were further confirmed using Raman spectroscopy. From SEM analysis, a clear surface morphology change is noticed for fluorite, hybrid and monoclinic phases of the CHx binary metal oxides. Further, Selected Area Electron Diffraction (SAED) analysis also confirmed the single and hybrid phases of CHx binary metal oxides. The soot oxidation for the CHx binary metal oxides displayed high catalytic activity for Fluorite phase (CH10 ? CH30) samples and a decrease in catalytic activity is noticed for the Hybrid phase (CH40 ? CH90) samples. The change in catalytic activity coincides with the change in the surface morphology and phase change for the CHx binary metal oxides. Among the Fluorite phase samples, CH10 sample displayed the highest catalytic activity (T50 = 430 °C) with higher surface area (29 m2/g), lower particle size (26 nm), lower degree of agglomeration (? = 2.8) higher surface oxygen concentration (44%). Isothermal-Time-on-stream (ITOS) analysis also showed that the CH10 sample can achieve T50 in a shorter time than compared to other CHx binary metal oxides. Surface morphology and phase stability can also play as key descriptors in screening CHx binary metal oxides for soot oxidation activity. © 2018 Elsevier B.V.Item Effect of synthesis method on structural properties and soot oxidation activity of gadolinium-doped ceria(Springer International Publishing kasia@cesj.com, 2018) Anjana, A.P.; Gadiyar, H.J.; Surendran, M.; Rao, A.S.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.Abstract: EDTA–citrate complex and solvothermal methods were adopted for the synthesis of gadolinium-doped ceria (GDC) (Ce0.9Gd0.1O2) solid solution, and the obtained GDC sample is tested for soot oxidation activity. Based on XRD results, it was evident that the reactive facet planes of {100} and {110} were highly intense [intensity ratio (%) of (200)/(100) (34.2%) and (220)/(111) (51.2%)] for GDC prepared by the EDTA–citrate method in comparison with the solvothermal method, and this highly intense reactive facet plane correlates to the lower energy for oxygen vacancy formation. Apart from the smaller crystallite size (10 nm) the GDC sample prepared by the EDTA–citrate method displayed lower band gap energy (2.99 eV), higher ratio of reducibility (45.45%) and lower binding energy (528.8 eV) for surface-adsorbed oxygen. The GDC obtained by EDTA–citrate method displayed a better soot oxidation activity (T50 = 468 °C) than compared to the GDC obtained by solvothermal method (T50 = 500 °C). The obtained results significantly show that the synthesis method plays a crucial role in controlling the structural properties and in enhancing the soot oxidation activity. © 2018, Institute of Chemistry, Slovak Academy of Sciences.