Twenty years of operando IR, X-ray absorption, and Raman spectroscopy: Direct methanol and hydrogen fuel cells
Twenty years of operando IR, X-ray absorption, and Raman spectroscopy: Direct methanol and hydrogen fuel cells
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DOI：
10.1016/j.cattod.2016.06.012
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发表时间：
2017-04
期刊：
影响因子：
5.3
通讯作者：
Neili Loupe;Jonathan Doan;E. Smotkin
中科院分区：
文献类型：
--
作者：
Neili Loupe;Jonathan Doan;E. Smotkin
采用原位红外、X射线吸收和拉曼光谱对聚合物电解质燃料电池膜电极组件中的混合金属催化剂进行了表征。带窗口的直接甲醇和氢-空气燃料电池组件允许在受控电位、温度和流向石墨流场的反应物流的情况下进行光谱采集。研究了庄信万丰 Pt 和 PtRu (1:1)、内部制备的 PtRu（1:1 和 3:1）、PtRuOs (65:25:10)、PtNi (1:1) 和三聚氰胺合成的 FeNC 催化剂。相偏合金催化剂的核心结构在实际燃料电池电势上几乎不变，使得金属组分 EXAFS 能够同时拟合，以定量表征核心结构：JM PtRu 是面心立方晶格，其中 50% 的 Ru 处于非晶相。 COads 作为反应中间体和表面结构探针的斯塔克调谐阐明了 Nafion 官能团在 Pt 上的潜在依赖性共吸附。 Nafion IR 波段基于对称性的组模式分配促进了燃料阴极膜水合的操作拉曼光谱跟踪。完全水合的 Nafion 磺酸盐基团具有 C3V 局部对称性。脱水磺酸基团具有C1局部对称性。 C3V 和 C1IR 谱带在膜水合的中间状态中共存。
Mixed metal catalysts in polymer electrolyte fuel cell membrane electrode assemblies were characterized by operando infrared, X-ray absorption and Raman spectroscopy. Windowed direct methanol and hydrogen-air fuel cell assemblies allow for spectral acquisition with controlled potential, temperature and flowing reactant streams to the graphite flow fields. Johnson Matthey Pt and PtRu (1:1), in-house prepared PtRu (1:1 and 3:1), PtRuOs (65:25:10), PtNi (1:1), and a melamine-synthesized FeNC catalyst were studied. The near invariant core structure of phase segregated alloy catalysts over practical fuel cell potentials enable a simultaneous fit of metal component EXAFS to quantitatively characterize core structures: JM PtRu is a face centered cubic lattice with 50% of the Ru in an amorphous phase. Stark tuning of COadsas a reaction intermediate and as a surface structure probe elucidates potential dependent co-adsorption of Nafion functional groups on Pt. Operando Raman spectroscopic tracking of membrane hydration at a fuel cathode is facilitated by symmetry-based group mode assignments of Nafion IR bands. Fully hydrated Nafion sulfonate groups have C3Vlocal symmetry. Dehydrated sulfonic acid groups have C1local symmetry. C3Vand C1IR bands coexist at intermediate states of membrane hydration.