The role of porosity, and more specifically, microporosity, in the performance of carbon materials as Oxygen Reduction Reaction (ORR) catalysts in alkaline medium still has to be clarified. For this purpose, a highly microporous KOH-activated carbon and a microporous char have been prepared and their ORR performance in alkaline media were compared to that of two commercial carbon blacks with low and high surface areas, respectively. Interestingly, all carbon materials show a two-wave electrocatalytic process, where the limiting current and the number of electron transferred increase when going to more negative potentials. The limiting current and onset potential of the second wave is positively related to the amount of microporosity, and H₂O₂ electrochemical reduction tests have confirmed that the second wave could be related to the catalytic activity towards this reaction. In accordance to these findings, a model is developed that takes into account narrow and wide micropores in both charge transfer reactions and the mass transfer rate of O₂ and H₂O₂. This model successfully reproduces the experimental electrochemical response during ORR of the analyzed porous carbon materials and suggests the important role of narrow micropores in H₂O₂ reduction.

在碱性介质中，作为氧气还原反应（ORR）催化剂的碳材料的性能中，孔隙度（更具体而言是微孔）的作用仍然需要弄清楚。为此，已经制备了高度微孔的KOH活性炭和微孔炭，并将它们在碱性介质中的ORR性能分别与两种低表面积和高表面积的商业炭黑进行了比较。有趣的是，所有碳材料都表现出两波电催化过程，当进入更多的负电势时，极限电流和转移的电子数量增加。第二波的极限电流和起始电势与微孔量和H ₂ O ₂正相关电化学还原测试已证实第二波可能与对该反应的催化活性有关。根据这些发现，开发了一种模型，该模型考虑了电荷转移反应和O ₂和H ₂ O ₂的质量转移率中的窄孔和宽孔。该模型成功地再现了所分析的多孔碳材料在ORR期间的实验电化学响应，并表明了窄微孔在H ₂ O ₂还原中的重要作用。