Date of Award
2025
Document Type
Open Access Dissertation
Department
Mechanical Engineering
First Advisor
Kevin Huang
Abstract
This dissertation investigates novel materials designed to significantly enhance the performance and durability of oxygen electrodes for solid oxide cells and redox active materials for thermochemical hydrogen production. The first part of this work evaluates Ta-doped BaCoO₃₋δ (BCT) and its structural analog SrCoO₃₋δ (SCT), focusing on their catalytic performance in oxygen reduction and evolution reactions. Among BCT compositions (x = 0.1, 0.3, 0.5), the BCT10 (x = 0.1) composition exhibited the highest oxygen vacancy concentration, electronic conductivity, and lowest polarization resistance. However, SCT10 surpassed BCT10 in these critical performance parameters and also demonstrated greater stability over extended operational periods. Notably, SCT10’s superior catalytic activity is attributed to its larger Co–O octahedron, despite having a smaller overall unit cell compared to BCT10. The second part introduces a barrier-layer-free (BLF) oxygen electrode (OE) consisting of a composite of (Bi₀.₇₅Y₀.₂₅)₀.₉₃Ce₀.₀₇O₁.₅±δ (BYC), a high oxide-ion conductor, and La₀.₈Sr₀.₂MnO₃ (LSM), an electronic conductor. The innovative electrode design, achieved through infiltration of LSM nanoparticles into a porous BYC scaffold, delivered remarkably low area-specific resistance (0.10 Ω·cm²) and significantly improved current densities in both fuel cell and electrolytic modes. Durability testing over 550 hours confirmed exceptional stability, demonstrating its suitability for high-performance intermediate-temperature solid oxide cells. Finally, the third study investigates Pr₃ZrO₈-δ (PZO) as a new redox-active oxide for intermediate-temperature “two-step” thermochemical hydrogen production. Operating effectively at significantly reduced temperatures (900°C reduction and 400°C water splitting), PZO demonstrated superior oxygen vacancy concentrations and hydrogen generation rates compared to conventional CeO₂-based materials. With stable performance through multiple redox cycles, PZO demonstrates itself as a promising redox material for practical thermochemical hydrogen production utilizing lower-temperature heat sources. Collectively, these findings advance the fundamental understanding and practical applications of high-performance electrode materials and hydrogen production technologies, offering significant contributions toward sustainable and efficient energy conversion solutions.
Rights
© 2025, Jiaxin Lu
Recommended Citation
Lu, J.(2025). Novel Redox Oxygen Active Materials for Solid Oxide Cells and Thermochemical Hydrogen Production. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8324