Pawan Kumar Dubey

PCO (Praseodymium Cerium Oxide) solid solution (0-50% PrOx) has been prepared by the conventional solid-state ceramic processing of mixed CeO₂ and PrOx powders in the desired stoichiometry at 1500°C in air. Synthesized powder has been characterized for phase chemistry and lattice structure. Electrochemical characteristics of the synthesized powder has been examined using electrochemical impedance spectroscopy. The observed increase in the electrical conductivity of PCO are associated with increased concentration of oxygen vacancies created by replacement of Ce⁴⁺ ions with Pr⁺³ ions. The addition of PrOx also lowered the polarization and ohmic losses.

State of the art SOFCs, consisting of Ni base anode, experience excessive localized endothermic cooling and carbon deposition during internal reforming of hydrocarbon fuels. To mitigate the above issues, we developed high-entropy alloy (HEA) anode consisting of optimized mixture of Cu, Ni, Co, Fe and Mn transition metals. Alloys were synthesized using co-precipitation technique and experimentally evaluated for internal reforming and electrochemical activity under SOFC operating conditions. As-synthesized HEA catalysts were also characterized by techniques including N₂ adsorption/desorption analysis, SEM, XRD, TPR, TPO and TPD. Compared with standard Ni/YSZ and Ni/GDC anodes, HEA anode containing gadolinium-doped ceria (GDC) showed controlled reforming of methane. Raman spectroscopy and SEM microscopy confirmed the absence of carbon on the HEA/GDC anode.

Electrochemical systems operating at elevated temperatures such as solid oxide fuel cells (SOFC), solid oxide electrolysis cells (SOEC) and oxygen transport membranes (OTM) are susceptible to electrochemical performance degradation due to the presence of intrinsic and extrinsic contaminants in air stream. Intrinsic and extrinsic airborne contaminants include a wide range of gaseous compounds consisting of cations such as Cr, Si, and B, intrinsic impurities include SOx, NOx, VOC and PM’s. During high temperature exposure, the contaminants deposit and react with the cell components leading to both ohmic and non-ohmic polarization buildup. The use of a cost-effective, design-agnostic, passive “getter” system has been proposed for capturing trace contaminants. A number of getter formulations (containing alkaline earth, transition metal and lanthanide group elements) have been synthesized and experimentally tested. Results will be presented.

PCO (Praseodymium Cerium Oxide) solid solution (0-50% PrOx) has been prepared by the conventional solid-state ceramic processing route using CeO2 and PrOx powders in the desired stoichiometry and sintering at 1500°C in air. Synthesized powder has been characterized for phase chemistry and lattice structure. Electrochemical characteristics of the synthesized powder has been examined using electrochemical impedance spectroscopy. The observed increase in the electrical conductivity of PCO are associated with increased concentration of oxygen vacancies created by the replacement of Ce⁴⁺ ions with Pr⁺³ ions. The addition of PrOx also lowered the polarization and ohmic losses.