Wang Haocong, Zhang Wenwen, Meng Junling, Pei Yongli, Qiu Xin, Meng Fanzhi, Liu Xiaojuan
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
University of Science and Technology of China, Hefei 230026, Anhui, China.
ACS Appl Mater Interfaces. 2021 May 26;13(20):24329-24340. doi: 10.1021/acsami.1c06757. Epub 2021 May 12.
The development of multiphase composite electrocatalysts plays a key role in achieving the efficient and durable operation of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a self-assembled nanocomposite is developed as the oxygen reduction reaction (ORR) catalyst for IT-SOFCs through a coprecipitation method. The nanocomposite is composed of a doped (MnMg)ScCoO (MMSCO) spinel oxide (84 wt %), an orthorhombic perovskite phase (11.3 wt %, the spontaneous combination of PrO additives and spinel), and a minor ScO phase (4.7 wt %). The surface of the (MnMg)ScCoO phase is activated by the self-assembled nanocoating with many heterogeneous interfaces. Thence, the ORR kinetics is obviously accelerated and an area-specific resistance (ASR) of ∼0.11 Ω cm is obtained at 750 °C. Moreover, a single cell with the cathode shows a peak power density (PPD) of 1144.1 mW cm at 750 °C, much higher than that of the cell with the MnCoO cathode (456.2 mW cm). An enhanced stability of ∼120 h (0.8 A cm, 750 °C) is also achieved, related to the reduced thermal expansion coefficient (13.9 × 10 K). The improvement in ORR kinetics and stability can be attributed to the refinement of grains, the formation of heterointerfaces, and the enhancement of mechanical compatibility.
多相复合电催化剂的开发对于实现中温固体氧化物燃料电池（IT-SOFCs）的高效持久运行起着关键作用。在此，通过共沉淀法制备了一种自组装纳米复合材料作为IT-SOFCs的氧还原反应（ORR）催化剂。该纳米复合材料由掺杂的（MnMg）ScCoO（MMSCO）尖晶石氧化物（84 wt%）、正交钙钛矿相（11.3 wt%，PrO添加剂与尖晶石的自发结合）和少量ScO相（4.7 wt%）组成。（MnMg）ScCoO相的表面通过具有许多异质界面的自组装纳米涂层而被活化。因此，ORR动力学明显加快，在750°C时获得了约0.11Ω·cm的面积比电阻（ASR）。此外，带有该阴极的单电池在750°C时的峰值功率密度（PPD）为1144.1 mW/cm²，远高于带有MnCoO阴极的电池（456.2 mW/cm²）。还实现了约120小时（0.8 A/cm²，750°C）的增强稳定性，这与降低的热膨胀系数（13.9×10⁻⁶ K⁻¹）有关。ORR动力学和稳定性的提高可归因于晶粒细化、异质界面的形成以及机械相容性的增强。
