氧还原反应(ORR)是一个复杂的过程,尤其在碱性电解液中,炭载型催化剂表面的ORR路径尤为复杂,因为碳本身可以催化ORR以二电子转移过程发生,产生过氧化氢,继而过氧化氢或者发生化学分解生成氧气(HODR),或者发生电化学还原生成OH–(HORR)。本文详细研究了ORR在常用氧化锰催化剂表面的反应路径。通过比较HODR和HORR的转换频率发现,尽管利用旋转环盘电极方法得到的表观电子转移数接近4,真实的ORR主要是2电子过程,反应生成的过氧化氢继而大部分发生化学分解生成氧气。该结果有助于理解碱性电解质中炭载型过渡金属氧化物电催化剂对ORR的催化行为。
The oxygen reduction reaction (ORR) is a complex process. This is particularly the case for car‐bon‐supported electrocatalysts in alkaline electrolytes, because carbon can catalyze the ORR via a two‐electron transfer to generate hydroperoxide (HO2?), which subsequently undergoes either chemical decomposition to generate O2 and OH? (HODR) or electrochemical reduction to OH?(HORR). In this study, we elucidated the ORR pathway on a series of carbon‐supported manganese oxides, which have been extensively studied as electrocatalysts in alkaline electrolytes. A compari‐son of the turnover frequencies of the HODR and HORR showed that although an apparent four‐electron transfer process was identified when the HO2?yield was measured using the rotating ring disk electrode technique, the real ORR pathway involved a two‐electron transfer process to generate HO2?, with subsequent chemical decomposition of HO2?. These results will help us to un‐derstand the intrinsic catalytic behavior of carbon‐supported transition‐metal oxides for the ORR in alkaline electrolytes.
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