Controlled growth of Pr1.5Ba1.5Cu3O7 cubes to meliorate the cathode reaction for protonic ceramic fuel cells

Generating electricity affordably and environmental-friendly stands as a pivotal challenge in steering our society towards a sustainable future. Solid oxide fuel cells (SOFCs) have garnered significant attention as a promising solution, for their remarkable efficiency and low environmental footprint. Particularly, protonic ceramic fuel cells (PCFCs) have attracted considerable interest for their capacity to function at low temperatures (LTs, ≤ 600 °C), uphold sufficient electrolyte conductivity (≥ 0.01 S cm^-1), and exhibit low activation energy, thereby establishing them as viable contenders in the commercial arena. Nevertheless, as operating temperatures decrease, a significant hurdle arises from the constrained electrocatalytic activity of cathode, predominantly due to the sluggish kinetics of the oxygen reduction reaction (ORR). Then developing highly active and durable cathode materials is crucial for PCFC application.

Recently, a team of material scientists led by Jie Hou from University of South China first reported the controlled growth of Pr_1.5Ba_1.5Cu₃O₇ (PBC) cubes and their optimization effect on cathode reactions in protonic ceramic fuel cells (PCFCs). This study systematically explores the impact of calcination temperatures (900 °C, 950 °C, 1000 °C) on the microstructure of PBC powders (particle morphology, lattice parameters, interplanar spacing, and size distribution) and their electrochemical performance. Through morphological characterization, surface elemental analysis, power output comparison, and DRT analysis, the study reveals the promoting effect of cubic morphology on the oxygen reduction reaction (ORR) at the cathode. This work highlights the importance of exploring materials with specific particle geometries to activate specialized properties at particular lattice planes, and thereby meeting specific requirements in related electrocatalytic fields.

The team published their work in Journal of Advanced Ceramics on March 5, 2023.

In this assignment, the perovskite-related PBC is successfully applied as a stand-alone cathode for PCFC and the amelioration of PBC is attempted via the controllable growth of PBC cubes. Consequently, the PBC particle geometry changes from sphericity to cube at 950 ℃, resulting in the exposure of {100} crystal facets on the cube surface. This creates more efficient Cu²⁺-O-Cu³⁺ electron-hopping transition paths and much higher surface oxygen vacancy concentration, leading to higher electrocatalytic activity with promoted oxygen adsorption and activation at active sites, and thus facilitating the ORR process.

Resultantly, the particle-cubic PBC-950 cathode shows a remarkably enhanced cell performance with the power output of 1982, 1281, 797 and 477 mW cm^-2, along with the R_P of 0.028, 0.069, 0.164 and 0.376 Ω cm² at 700, 650, 600 and 550 °C, respectively. Comparatively, the PBC-950 cell outperforms both PBC-900 and PBC-1000 cell significantly. Though the PBC is firstly ameliorated via configuring specific particle geometry, its performance surpasses that of PCFC employing Co-based and Cu-based single-phase cathodes reported in the literature.

Crucially, the favorable electrochemical performance does not compromise its durability, indicating the high potential for utilization of particle-cubic cathode in PCFCs. This attempt of configuring materials with specific particle geometry could be significant for the possible exposure of special crystal facets with specialized properties, which could meet particular needs and provide a path towards new material designs in PCFC and related electrocatalytic fields.

Other contributors include Junyi Gong, Kunpeng Du, Wang Jiang, Shenchi Qu from the School of Resource Environment and Safety Engineering, University of South China, Hengyang, China.

This work was supported by the National Natural Science Foundation of China (Grant Nos: 51802200) and the Startup Funding for Talents at University of South China.

About Author

Dr. Hou Jie, who graduated from the University of Science and Technology of China in 2017, has since conducted research with Professor John Irvine’s team at the University of St Andrews (UK) and with Professor Jingli Luo’s team (a member of the Canadian Academy of Engineering) at Shenzhen University. He currently serves as a Distinguished Professor and doctoral supervisor at University of South China, recognized as a “Young Outstanding Talent” at University of South China. Additionally, he is classified as a C-class talent under the Shenzhen Overseas High-Level Talent Introduction Program (“Peacock Plan”) and a selected talent under the Nanshan District Leading Talent program in Shenzhen.

Dr. Hou is also a young editorial board member of Energy Reviews, a high-starting-point new journal under the Excellent Action Plan for Chinese Scientific and Technological Journals, and a senior member of the Chinese Materials Research Society. His main research areas include solid oxide fuel cells/electrolyzers and functional membrane reactor devices. He has led several projects, including those funded by the National Natural Science Foundation of China. To date, he has published over 40 SCI papers in relevant fields, such as Chemical Engineering Journal, Journal of Materials Chemistry A, and Journal of Materials Science & Technology, and holds one authorized national invention patent.

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in “Materials Science, Ceramics” category, and its 2023 CiteScore is 21.0 (top 5%) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508

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