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首页> 外文期刊>ACS catalysis >Carbon-Supported Platinum Electrocatalysts Probed in a Gas Diffusion Setup with Alkaline Environment: How Particle Size and Mesoscopic Environment Influence the Degradation Mechanism
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Carbon-Supported Platinum Electrocatalysts Probed in a Gas Diffusion Setup with Alkaline Environment: How Particle Size and Mesoscopic Environment Influence the Degradation Mechanism

机译：碳载铂电催化剂探测在碱性环境中的气体扩散设置中：粒径和介观环境如何影响降解机制

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In recent years, extensive research has been performed concerning the stability of fuel cell catalysts in an acidic environment. By comparison, only few studies address the degradation mechanism(s) of fuel cell catalysts in alkaline media. In this work, we investigate the stability of four different types of Pt/C fuel cell catalysts upon applying accelerated degradation tests in a gas diffusion electrode (GDE) setup equipped with an anion exchange membrane. In contrast to previous investigations exposing the catalysts to a liquid electrolyte, the GDE setup provides a realistic three-phase boundary of the reactant gas, catalyst, and ionomer which enables reactant transport rates close to real fuel cells. Therefore, the GDE setup mimics the degradation of the catalyst under more realistic reaction conditions as compared to conventional electrochemical cells. Combining the determination of the loss in the electrochemically active surface area of the Pt/C catalysts via CO stripping measurements with the change in particle size distribution determined by small-angle X-ray scattering measurements, we demonstrate that (i) the degradation mechanism depends on the investigated Pt/C catalyst and might indeed be different from the one observed in conventional electrochemical cells, (ii) degradation is increased in an oxygen gas atmosphere (as compared to an inert atmosphere), and (iii) the observed degradation mechanism depends on the mesoscopic environment of the active phase. The measurements indicate an increased particle growth if small and large particles are immobilized next to each other on the same carbon support flakes as compared to a simple mix of two catalysts with small and large particles, respectively.
机译：近年来，已经进行了广泛的研究，关于酸性环境中的燃料电池催化剂的稳定性。相比之下，只有少数研究才能解决碱性介质中燃料电池催化剂的降解机制。在这项工作中，我们在配备有阴离子交换膜的气体扩散电极（GDE）设置中施加加速降解试验时，研究四种不同类型的Pt / C燃料电池催化剂的稳定性。与将催化剂暴露于液体电解质的先前研究相反，GDE设置提供了反应气体，催化剂和离聚物的现实三相边界，其使得能够接近真实燃料电池的反应物运输速率。因此，与常规电化学电池相比，GDE设置在更现实的反应条件下模拟催化剂的降解。通过CO剥离测量与通过小角度X射线散射测量确定的粒度分布的变化的CO剥离测量结合测定Pt / C催化剂的电化学表面积的损失，我们证明（i）降解机制取决于在所研究的Pt / C催化剂上并且可能与在常规电化学电池中观察到的催化剂不同，（ii）在氧气气氛中劣化（与惰性气氛相比）增加，并且（iii）观察到的降解机制取决于在活性阶段的介观环境上。如果小颗粒在相同的碳载薄片上彼此相邻地固定在相同的两种催化剂的简单混合物，则测量值增加了颗粒生长增加，并且与具有小颗粒的两种催化剂的简单混合物，分别是相同的。

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