Shi Nai, Zhu Kang, Xie Yun, Huan Daoming, Hyodo Junji, Yamazaki Yoshihiro
Kyushu University Platform of Inter-/Transdisciplinary Energy Research, Kyushu University, 744 Motooka, Fukuoka, 819-0395, Japan.
CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui, 230026, China.
Small. 2024 Sep;20(36):e2400501. doi: 10.1002/smll.202400501. Epub 2024 May 1.
Water, being abundant and readily accessible, gains widespread usage as proton source in many catalysis and energy conversion technologies, including applications like reversible protonic ceramic cells (R-PCCs). Revealing the influence of water on the electrode surface and reaction kinetics is critical for further improving their electrochemical performance. Herein, a hydrophilic air-electrode PrBaCsCoO is developed for R-PCC, which demonstrates a remarkable peak power density of 1058 mW cm in fuel cell mode and a current density of 1354 mA cm under 1.3 V in electrolyzing steam at 650 °C. For the first time on R-PCC, surface protons' behavior in response to external voltages is captured using in situ FTIR characterizations. Further, it is shown that contrary to the bulk proton uptake process that is thought to follow hydrogenation reactions and lead to cation reductions. The air-electrode presents enriched surface protons occurring through oxidizing surface cations, as confirmed by depth-profiling XPS results. H/D isotope exchange experiments and subsequent electrochemical characterization analyses reveal that the presence of protons enhances surface reactions. This study fills the knowledge gap between water-containing atmospheres and electrochemical performance by providing insights into the surface properties of the material. These new findings provide guidance for future electrode design and optimization.
水储量丰富且易于获取，在许多催化和能量转换技术中作为质子源得到广泛应用，包括可逆质子陶瓷电池（R-PCCs）等应用。揭示水对电极表面和反应动力学的影响对于进一步提高其电化学性能至关重要。在此，开发了一种用于R-PCC的亲水性空气电极PrBaCsCoO，在燃料电池模式下其峰值功率密度达到1058 mW/cm²，在650°C电解蒸汽时，在1.3 V电压下电流密度为1354 mA/cm²。首次在R-PCC上利用原位傅里叶变换红外光谱（FTIR）表征捕获了表面质子对外加电压的响应行为。此外，研究表明，与认为遵循氢化反应并导致阳离子还原的体相质子吸收过程过程相反，空气电极表面质子通过氧化表面阳离子而富集，深度剖析X射线光电子能谱（XPS）结果证实了这一点。氢/氘同位素交换实验及后续的电化学表征分析表明，质子的存在增强了表面反应。本研究通过深入了解材料的表面性质，填补了含水气氛与电化学性能之间的知识空白。这些新发现为未来电极的设计和优化提供了指导。
