Large scale CO₂ electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO₂ reduction to CO. We have used shear–force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO₂ reduction as a function of catalyst loading and CO₂ back pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO₂ back pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO₂ back pressure on their performance.

中文翻译：

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探讨金气体扩散电极上 CO2 还原的局部活性：催化剂负载和 CO2 压力的影响

使用气体扩散电极 (GDE) 可以实现大规模 CO ₂电解，这是更广泛地实施碳捕获和利用战略的重要一步。已知不同的变量会影响 GDE 的性能。尤其是在催化剂负载方面，据报道在活性和选择性方面存在不同的趋势，例如CO ₂还原为 CO。我们在表面生成尖端收集中使用了基于剪切力的 Au 纳米电极定位和扫描电化学显微镜 (SECM)用于评估 Au GDE 的 CO ₂还原活性与催化剂负载量和 CO ₂的函数关系的模式背压。使用 Au 纳米电极，我们局部测量了在操作条件下沿催化剂负载梯度产生的 CO 量。我们观察到催化剂的最佳局部负载对于实现高活性是必要的。然而，该最佳值直接取决于CO ₂背压。我们的工作不仅提供了一种在当地评估 GDE 活性的工具，而且还可以更精确地描绘催化剂负载和 CO ₂背压对其性能的影响。