This paper critically evaluates three methods for determining metrics of the oxygen evolution reaction (OER) describing the performance and stability of low-loading iridium-based anode catalyst layers (CLs) in proton exchange membrane water electrolysis (PEMWE) cells. The methods applied are OER mass activity, voltage breakdown analysis (VBA), and constant Tafel slope VBA (CT-VBA). They are used to assess the OER metrics as a function of anode CL configurations, potential cycling, and level of degradation. Therefore, various accelerated stress tests (ASTs) are carried out for a targeted degradation of different anode CLs based on Ir black or Ir oxide. It turns out that the OER mass activity method is robust, straightforward and an ideal method for e.g., in-house screening tasks. On the other hand, the VBA method is suitable for comparative analysis across laboratories by distinguishing between the three main overpotentials. The CT-VBA method, however, offers improved accuracy, as it accounts for mass transport overpotential at low current density, and is particularly suitable for determining apparent exchange current density values further used in modelling approaches. This benefit comes with a drawback, as commonly accepted reference Tafel slopes for respective catalyst type and PTL configurations would be required within the PEMWE community. This guidance therefore helps to choose the right method for determining OER metrics depending on the research question.

中文翻译：

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PEM 水电解槽中低负载铱基催化剂的 OER 动力学靶向降解分析指南


本文批判性地评估了三种确定析氧反应 （OER） 指标的方法，这些反应描述了质子交换膜水电解 （PEMWE） 电池中低负载铱基阳极催化剂层 （CLs） 的性能和稳定性。应用的方法包括 OER 质量活度、电压击穿分析 （VBA） 和恒定塔菲尔斜率 VBA （CT-VBA）。它们用于评估 OER 指标与阳极 CL 配置、潜在循环和降解水平的函数关系。因此，进行了各种加速应力测试 （AST），以针对基于 Ir 黑或 Ir 氧化物的不同阳极 CL 进行靶向降解。事实证明，OER 质量活性方法稳健、简单，是内部筛选任务等的理想方法。另一方面，VBA 方法通过区分三个主要过电位，适用于跨实验室的比较分析。然而，CT-VBA 方法提供了更高的精度，因为它考虑了低电流密度下的质量传输过电位，特别适用于确定进一步用于建模方法的视在交换电流密度值。这个好处也有一个缺点，因为在 PEMWE 社区内需要针对相应催化剂类型和 PTL 配置的普遍接受的参考塔菲尔斜率。因此，本指南有助于根据研究问题选择正确的方法来确定 OER 指标。