A series of hybrid catalysts for the oxygen reduction reaction (ORR) has been investigated. They are composed of multi-wall carbon nanotubes (MWNTs) coated with iron strapped porphyrins. Two porphyrins have been probed; both are strapped with the same skeleton and differ only by the number of overhung carboxylic acid(s), either one or two. In this structure, the carboxylic acid group can act as a proton relay between the medium and the catalyst or as a polar group surrounding the dioxygen binding cavity. While the number of carboxylic acid group(s) does not exhibit a significant influence on the catalytic properties, the combination of both components–MWNTs and porphyrin–leads to a better catalytic activity than those of the nanotubes or the porphyrins taken separately.

中文翻译：

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碳纳米管上吸附的悬垂羧酸束缚铁卟啉催化氧还原反应

已经研究了一系列用于氧还原反应（ORR）的混合催化剂。它们由涂有铁带卟啉的多壁碳纳米管 (MWNT) 组成。已经探测了两种卟啉；两者都绑有相同的骨架，仅在悬垂羧酸的数量上有所不同，一个或两个。在这种结构中，羧酸基团可以充当介质和催化剂之间的质子中继，或充当围绕分子氧结合腔的极性基团。虽然羧酸基团的数量对催化性能没有显着影响，但与单独使用的纳米管或卟啉组分相比，MWNT 和卟啉这两种组分的组合具有更好的催化活性。