Transition‐metal oxide/nanocarbon hybrids are known to deliver a cooperative oxygen reduction reaction (ORR) with a synergistic effect of the hybrid interface. This work assesses a series of first‐row transition‐metal oxides in the form of surface‐confined clusters on carbon nanotubes, as a mimic of fully exposed hybrid interfaces, providing an activity benchmark for hybrid catalysts. Among the selected metal oxides, MnO_x and CoO_x are found to be the most active first‐row transition‐metal oxide clusters for the ORR, given their excellent peroxide‐reducing capability at low overpotential. FeO_x and CuO_x are also active for the same role, except their peroxide‐reducing activity is only activated with substantial overpotential. Other metal oxides (NiO_x and ZnO_x) do not appear to show any activity toward the ORR, even with an integrated interface as a source for the possible synergistic effect.

中文翻译：

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基准测试碳纳米管上第一行过渡金属氧化物簇的氧还原电活性

已知过渡金属氧化物/纳米碳杂化物可产生协同的氧还原反应（ORR），并具有杂化物界面的协同作用。这项工作评估了一系列第一行过渡金属氧化物，以碳纳米管上表面受限簇的形式存在，模拟了完全暴露的杂化界面，为杂化催化剂提供了活性基准。在选定的金属氧化物中，发现MnO _x和CoO _x是ORR活性最高的第一行过渡金属氧化物簇，因为它们在低电势下具有出色的过氧化物还原能力。FeO _x和CuO _x它们也具有相同的作用，只是它们的减少过氧化物的活性仅在相当大的超电势下才被激活。其他金属氧化物（NiO _x和ZnO _x）似乎没有表现出对ORR的任何活性，即使使用集成界面作为可能产生协同作用的来源。