当前位置：
X-MOL 学术
›
ACS Appl. Mater. Interfaces
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Operando Imaging of Ce Radical Scavengers in a Practical Polymer Electrolyte Fuel Cell by 3D Fluorescence CT–XAFS and Depth-Profiling Nano-XAFS–SEM/EDS Techniques
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2022-01-25 , DOI: 10.1021/acsami.1c22336 Hirosuke Matsui 1 , Shinobu Takao 2 , Kotaro Higashi 2 , Takuma Kaneko 2 , Gabor Samjeské 1 , Tomoya Uruga 2, 3 , Mizuki Tada 1, 4 , Yasuhiro Iwasawa 2, 5
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2022-01-25 , DOI: 10.1021/acsami.1c22336 Hirosuke Matsui 1 , Shinobu Takao 2 , Kotaro Higashi 2 , Takuma Kaneko 2 , Gabor Samjeské 1 , Tomoya Uruga 2, 3 , Mizuki Tada 1, 4 , Yasuhiro Iwasawa 2, 5
Affiliation
|
There is little information on the spatial distribution, migration, and valence of Ce species doped as an efficient radical scavenger in a practical polymer electrolyte fuel cell (PEFC) for commercial fuel cell vehicles (FCVs) closely related to a severe reliability issue for long-term PEFC operation. An in situ three-dimensional fluorescence computed tomography–X-ray absorption fine structure (CT–XAFS) imaging technique and an in situ same-view nano-XAFS–scanning electron microscopy (SEM)/energy-dispersive spectrometry (EDS) combination technique were applied for the first time to perform operando spatial visualization and depth-profiling analysis of Ce radical scavengers in a practical PEFC of Toyota MIRAI FCV under PEFC operating conditions. Using these in situ techniques, we successfully visualized and analyzed the domain, density, valence, and migration of Ce scavengers that were heterogeneously distributed in the components of PEFC, such as anode microporous layer, anode catalyst layer, polymer electrolyte membrane (PEM), cathode catalyst layer, and cathode microporous layer. The average Ce valence states in the whole PEFC and PEM were 3.9+ and 3.4+, respectively, and the Ce3+/Ce4+ ratios in the PEM under H2 (anode)–N2 (cathode) at an open-circuit voltage (OCV), H2–air at 0.2 A cm–2, and H2–air at 0.0 A cm–2 were 70 ± 5:30 ± 5%, as estimated by both in situ fluorescence CT–X-ray absorption near-edge spectroscopy (XANES) and nano-XANES–SEM/EDS techniques. The Ce3+ migration rates in the electrolyte membrane toward the anode and cathode electrodes ranged from 0.3 to 3.8 μm h–1, depending on the PEFC operating conditions. Faster Ce3+ migration was not observed with voltage transient response processes by highly time-resolved (100 ms) and spatially resolved (200 nm) nano-XANES imaging. Ce3+ ions were suggested to be coordinated with both Nafion sulfonate (Nfsul) groups and water to form [Ce(Nfsul)x(H2O)y]3+. The Ce migration behavior may also be affected by the spatial density of Ce, interactions of Ce with Nafion, thickness and states of the PEM, and H2O convection, in addition to the PEFC operating conditions. The unprecedented operando imaging of Ce radical scavengers in the practical PEFCs by both in situ three-dimensional (3D) fluorescence CT–XAFS imaging and in situ depth-profiling nano-XAFS–SEM/EDS techniques yields intriguing insights into the spatial distribution, chemical states, and behavior of Ce scavengers under the working conditions for the development of next-generation PEFCs with high long-term reliability and durability.
中文翻译：
通过 3D 荧光 CT-XAFS 和深度剖析 Nano-XAFS-SEM/EDS 技术对实用聚合物电解质燃料电池中的 Ce 自由基清除剂进行操作成像
在用于商用燃料电池汽车 (FCV) 的实用聚合物电解质燃料电池 (PEFC) 中，作为有效自由基清除剂掺杂的 Ce 物种的空间分布、迁移和价态信息很少，这与长期严重的可靠性问题密切相关。长期 PEFC 操作。原位三维荧光计算机断层扫描-X射线吸收精细结构（CT-XAFS）成像技术和原位同视图纳米XAFS-扫描电子显微镜（SEM）/能量色散光谱（EDS）组合技术首次应用在PEFC操作条件下对丰田MIRAI FCV的实际PEFC中的Ce自由基清除剂进行操作空间可视化和深度剖析分析。使用这些原位技术，我们成功地可视化和分析了不均匀分布在 PEFC 组件中的 Ce 清除剂的域、密度、化合价和迁移，例如阳极微孔层、阳极催化剂层、聚合物电解质膜 (PEM)、阴极催化剂层和阴极微孔层。整个PEFC和PEM的平均Ce价态分别为3.9+和3.4+，开路H 2（阳极）-N 2（阴极）下PEM中的Ce 3+ /Ce 4+比值电压 (OCV)、H 2 –air at 0.2 A cm –2和 H 2 –air at 0.0 A cm –2分别为 70 ± 5:30 ± 5%，由两者估计原位荧光 CT-X 射线吸收近边光谱 (XANES) 和纳米 XANES-SEM/EDS 技术。电解质膜中Ce 3+向阳极和阴极电极的迁移速率范围为 0.3 至 3.8 μm h -1，具体取决于 PEFC 操作条件。通过高度时间分辨 (100 ms) 和空间分辨 (200 nm) 纳米 XANES 成像，在电压瞬态响应过程中未观察到更快的 Ce 3+迁移。建议Ce 3+离子与 Nafion 磺酸盐 (Nf sul ) 基团和水配位形成 [Ce(Nf sul ) x (H 2 O) y ] 3+. 除了 PEFC 操作条件外，Ce 迁移行为还可能受到 Ce 的空间密度、Ce 与 Nafion 的相互作用、PEM 的厚度和状态以及 H 2 O 对流的影响。通过原位三维 (3D) 荧光 CT-XAFS 成像和原位深度剖析纳米 XAFS-SEM/EDS 技术对实际 PEFC 中的 Ce 自由基清除剂进行前所未有的操作成像，对空间分布、化学Ce 清除剂在工作条件下的状态和行为，以开发具有高长期可靠性和耐用性的下一代 PEFC。
更新日期：2022-02-09
中文翻译：
通过 3D 荧光 CT-XAFS 和深度剖析 Nano-XAFS-SEM/EDS 技术对实用聚合物电解质燃料电池中的 Ce 自由基清除剂进行操作成像
在用于商用燃料电池汽车 (FCV) 的实用聚合物电解质燃料电池 (PEFC) 中，作为有效自由基清除剂掺杂的 Ce 物种的空间分布、迁移和价态信息很少，这与长期严重的可靠性问题密切相关。长期 PEFC 操作。原位三维荧光计算机断层扫描-X射线吸收精细结构（CT-XAFS）成像技术和原位同视图纳米XAFS-扫描电子显微镜（SEM）/能量色散光谱（EDS）组合技术首次应用在PEFC操作条件下对丰田MIRAI FCV的实际PEFC中的Ce自由基清除剂进行操作空间可视化和深度剖析分析。使用这些原位技术，我们成功地可视化和分析了不均匀分布在 PEFC 组件中的 Ce 清除剂的域、密度、化合价和迁移，例如阳极微孔层、阳极催化剂层、聚合物电解质膜 (PEM)、阴极催化剂层和阴极微孔层。整个PEFC和PEM的平均Ce价态分别为3.9+和3.4+，开路H 2（阳极）-N 2（阴极）下PEM中的Ce 3+ /Ce 4+比值电压 (OCV)、H 2 –air at 0.2 A cm –2和 H 2 –air at 0.0 A cm –2分别为 70 ± 5:30 ± 5%，由两者估计原位荧光 CT-X 射线吸收近边光谱 (XANES) 和纳米 XANES-SEM/EDS 技术。电解质膜中Ce 3+向阳极和阴极电极的迁移速率范围为 0.3 至 3.8 μm h -1，具体取决于 PEFC 操作条件。通过高度时间分辨 (100 ms) 和空间分辨 (200 nm) 纳米 XANES 成像，在电压瞬态响应过程中未观察到更快的 Ce 3+迁移。建议Ce 3+离子与 Nafion 磺酸盐 (Nf sul ) 基团和水配位形成 [Ce(Nf sul ) x (H 2 O) y ] 3+. 除了 PEFC 操作条件外，Ce 迁移行为还可能受到 Ce 的空间密度、Ce 与 Nafion 的相互作用、PEM 的厚度和状态以及 H 2 O 对流的影响。通过原位三维 (3D) 荧光 CT-XAFS 成像和原位深度剖析纳米 XAFS-SEM/EDS 技术对实际 PEFC 中的 Ce 自由基清除剂进行前所未有的操作成像，对空间分布、化学Ce 清除剂在工作条件下的状态和行为，以开发具有高长期可靠性和耐用性的下一代 PEFC。
京公网安备 11010802027423号