Faculty Publications
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Item Electrochemical characterization of electrolyte supported solid oxide electrolysis cell during CO2/H2O co-electrolysis(Springer Science and Business Media Deutschland GmbH, 2024) Shirasangi, R.; Prasad Dasari, H.P.; Saidutta, M.B.High-temperature co-electrolysis is studied on electrolyte-supported NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF (NiO: Nickel Oxide, YSZ: Yttria-stabilized zirconia, SDC: Samarium-doped ceria, ScSZ: Scandia-stabilized zirconia, LSCF: Lanthanum Strontium Cobalt Ferrite, GDC: Gadolinium-doped ceria) button cell. Electrochemical impedance spectroscopy (EIS) was recorded under open-circuit voltage (OCV) and co-electrolysis mode over various operating conditions, including temperature, water vapor content, and applied voltage. Interfacial polarization resistance (Rp) is obtained from peak arcs located in the three regions: gas conversion resistance (Region I (0.01 to 0.1 Hz)), gas diffusion resistance (Region II (0.1 to 100 Hz)) and air electrode charge transfer resistance (Region III (100 to 10,000 Hz)). As the temperature increased from 700 to 850 oC, Rp decreased from 18.15 to 3.32 Ω.cm2 at 1.3 V for 10%CO2/3%H2O. From the Distribution of relaxation times (DRT) studies, one additional peak, P5 (fuel gas conversion or gas-phase diffusion in the pores of the air electrode), is observed, and Region III (100 to 10,000 Hz) consists of two additional peaks: P1 (ionic transport coupled with gas diffusion close to triple phase boundaries (TPBs)) and P2 (fuel electrode charge transfer reaction), which were not clearly distinguished from EIS. Region II dominates in the overall polarization resistance. At 800 oC, for 10%CO2/3%H2O, the Rp decreased from 6.78 to 4.82 Ω.cm2, with an increase in the applied voltage from 1.3 to 1.5 V. At 800oC/1.5 V, the Rp values are 4.41, 8.09, and 6.77 Ω.cm2 for H2O, CO2, and co-electrolysis. At 800 ºC/1.5 V, with an increase in the water vapor content from 3%H2O to 15%H2O, there is not much change in the Rp value; therefore, 10%H2O is sufficient. H2 consumption is between 23 and 36%, depending on the temperature at OCV. At 800 °C for (10%H2/10%CO2/10%H2O), co-electrolysis occurs at applied voltage, along with Reverse water gas shift (RWGS) reaction. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Item Study of CO oxidation activity of NiO-PDC and NiO-YSZ catalysts coated on alumina wash-coated honeycomb cordierite monolith(Springer Science and Business Media Deutschland GmbH, 2025) Wagay, A.A.; Shourya, A.; Patil, S.S.; Shirasangi, R.; Prasad Dasari, H.P.In this study, the EDTA-Citrate method was employed to synthesize NiO-PDC (NPC) and NiO-YSZ (NYZ) powder catalysts in nanostructured form. Subsequently, the catalysts were slurry dip-coated onto monolith cordierite substrates with alumina, using a one-step coating approach, and their CO oxidation activity was tested. The coating was achieved by first mixing the catalyst with the alumina suspension to prepare a homogeneous slurry, which was then used for dip coating onto the monolith. The adherence test was performed on the coated monolith to evaluate the mechanical stability of the catalyst-alumina composite layer. The coating was visually confirmed through optical imaging. The remaining powders (after coating) were then subjected to BET surface area, XRD, Raman spectroscopy, H2 TPR and O2 TPD analysis for characterization. Raman spectra showed that NPC exhibited higher oxygen vacancies than NYZ. H2 TPR and O2 TPD provided better evidence of the reduction potential and O2 desorption of NPC respectively. NPC/cord demonstrated the highest catalytic activity (T50 = 165 °C) compared to NYZ/cord (T50 = 215 °C) and bare cordierite (T50 = 777 °C), which is attributed to its better redox properties and higher oxygen vacancies. The effect of flow rate and heating rate on CO oxidation was studied on NPC/cord and NYZ/cord. The long-term stability of the NPC/cord and NYZ/cord were tested through 5-h and 50-h isothermal studies. © The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química 2025.Item Degradation studies over nickel foam current collector for supercapacitor application(Springer Science and Business Media B.V., 2025) Chakarayan, T.; Pallipad, A.; Shirasangi, R.; Purushothaman, P.; Prasad Dasari, H.P.The 3D porous structure of nickel foam makes it appealing as a current collector in supercapacitors. Cyclic voltammetry (CV) studies were conducted in a three-electrode cell with a 1.2 cm diameter Ni foam (working electrode), an Ag/AgCl (reference electrode), and a Pt (counter electrode) in KOH electrolyte solution. The effects of various scan rates, different concentrations of KOH, and degradation tests were evaluated. Characterization of Ni foam after cyclic study was carried out using X-Ray Diffraction (XRD), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and Field emission scanning electron microscopy (FESEM). The areal capacitance decreased from 341.71 to 196.83 mF cm? 2 with an increase in scan rate from 5 to 30 mV s? 1 for 1 M KOH. The increase in the redox peak currents is of order: 5 M > 3 M > 1 M > 7 M. From the XRD results, the Ni peak intensity decreased as the KOH concentration increased due to the formation of the oxide layer (NiOOH) following CV analysis. Bare Ni foam exhibited no peaks in the Raman spectra. However, the Ni foam after CV in 1, 3, 5, and 7 M KOH showed peaks around ~ 500–600 cm? 1 and ~ 1000 cm? 1, indicating the stretching vibrations of Ni-O and Ni-OH bonds, respectively. The peaks ~ 2800 cm? 1 indicate O-H stretching. From the FTIR spectra, the broad and weak peaks around ~ 3000–3750 cm? 1 for Ni foam after CV indicated O-H stretching, while peaks around ~ 1500–1650 cm? 1 and ~ 1100 cm? 1 represented hydroxyl and Ni-OH bending, respectively. Significant degradation was observed within the first 100 cycles. On the surface of the Ni foam, nanoflake structures were observed following the electrochemical measurements, indicating the presence of an oxide layer. This was confirmed by Energy Dispersive X-ray Spectroscopy (EDX) analysis, which revealed that the oxygen element’s weight%, along with potassium and carbon on the surface of Ni foam, increased with increasing KOH concentration. The maximum areal capacitance of 1628.44 mF cm? 2 at 5 mV s? 1 was obtained with 5 M KOH among the different electrolyte concentrations. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.