On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts
On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts
复制标题
反应物传输和（表面）合金形成对碳负载 PtRu 聚合物电解质燃料电池催化剂 CO 耐受性的作用
DOI：
10.1002/fuce.200500246
复制
发表时间：
2006
期刊：
影响因子：
2.8
通讯作者：
R. Behm
中科院分区：
文献类型：
--
作者：
J. Kaiser;L. Colmenares;Z. Jusys;R. Mörtel;H. Bönneman;G. Köhl;H. Modrow;J. Hormes;R. Behm
研究了原子尺度混合对重整操作的聚合物电解质燃料电池（PEFC）中PtRu阳极催化剂的电催化活性的作用，利用基于胶体的催化剂合成的特定性质选择性制备合金化和非合金化PtRu催化剂。具有不同程度的Pt和Ru混合的三种不同的碳负载的PtRu催化剂，由（i）碳负载的PtRu合金颗粒（PtRu/C），（ii）共沉积在相同碳载体上的Pt和Ru颗粒（Pt+Ru/C），和（iii）碳载Pt和碳载Ru的混合物制备了（Pt/C+Ru/C）以及相应的单组分Pt/C和Ru/C催化剂，并通过电子显微镜（TEM）、X射线吸收光谱和CO剥离进行表征。通过在旋转盘电极（RDE）装置中在燃料电池相关条件（升高的温度、连续反应和受控的反应物传输）下氧化H2/2%CO气体混合物（模拟重整产物）来评估它们作为PEFC阳极催化剂的性能。三种催化剂的CO耐受性和H2氧化活性相当，与单组分催化剂相比有明显差异。结果表明对于所有三种催化剂，反应物COad和/或OHad在Pt和Ru表面区域和颗粒之间的显著传输，从合金催化剂到物理混合物只有细微的差异。通过形成氧化物表面解释了氧化物催化剂的高活性和CO耐受性，例如，通过在纳米颗粒附聚物中的接触形成或通过在催化剂制备、调节和操作期间的材料输送和随后的表面装饰/表面合金形成。催化剂在这些条件下的不稳定性和流动性与气相催化的概念非常相似。
The role of atomic scale intermixing for the electrocatalytic activity of bimetallic PtRu anode catalysts in reformate operated polymer electrolyte fuel cells (PEFC) was investigated, exploiting the specific properties of colloid based catalyst synthesis for the selective preparation of alloyed and non‐alloyed bimetallic catalysts. Three different carbon supported PtRu catalysts with different degrees of Pt and Ru intermixing, consisting of (i) carbon supported PtRu alloy particles (PtRu/C), (ii) Pt and Ru particles co‐deposited on the same carbon support (Pt+Ru/C), and (iii) a mixture of carbon supported Pt and carbon supported Ru (Pt/C+Ru/C) as well as the respective monometallic Pt/C and Ru/C catalysts were prepared and characterized by electron microscopy (TEM), X‐ray absorption spectroscopy, and CO stripping. Their performance as PEFC anode catalysts was evaluated by oxidation of a H2/2%CO gas mixture (simulated reformate) under fuel cell relevant conditions (elevated temperature, continuous reaction and controlled reactant transport) in a rotating disk electrode (RDE) set‐up. The CO tolerance and H2 oxidation activity of the three catalysts is comparable and distinctly different from that of the monometallic catalysts. The results indicate significant transport of the reactants, COad and/or OHad, between Pt and Ru surface areas and particles for all three catalysts, with only subtle differences from the alloy catalyst to the physical mixture. The high activity and CO tolerance of the bimetallic catalysts, through the formation of bimetallic surfaces, is explained, e.g., by contact formation in nanoparticle agglomerates or by material transport and subsequent surface decoration/surface alloy formation during catalyst preparation, conditioning, and operation. The instability and mobility of the catalysts under these conditions closely resembles concepts in gas phase catalysis.