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Analysis of the limitations in the oxygen reduction activity of transition metal oxide surfaces
Nature Catalysis ( IF 37.8 ) Pub Date : 2021-05-24 , DOI: 10.1038/s41929-021-00618-w
Hao Li , Sara Kelly , Dan Guevarra , Zhenbin Wang , Yu Wang , Joel A. Haber , Megha Anand , G. T. Kasun Kalhara Gunasooriya , Christina Susan Abraham , Sudarshan Vijay , John M. Gregoire , Jens K. Nørskov

The oxygen reduction reaction (ORR) is the key bottleneck in the performance of fuel cells. So far, the most active and stable electrocatalysts for the reaction are based on Pt group metals. Transition metal oxides (TMOs) constitute an alternative class of materials for achieving operational stability under oxidizing conditions. Unfortunately, TMOs are generally found to be less active than Pt. Here, we identify two reasons why it is difficult to find TMOs with a high ORR activity. The first is that TMO surfaces consistently bind oxygen atoms more weakly than transition metals do. This makes the breaking of the O–O bond rate-determining for the broad range of TMO surfaces investigated here. The second is that electric field effects are stronger at TMO surfaces, which further makes O–O bond breaking difficult. To validate the predictions and ascertain their generalizability for TMOs, we report experimental ORR catalyst screening for 7,798 unique TMO compositions that generally exhibit activity well below that of Pt.



中文翻译:

过渡金属氧化物表面氧还原活性的局限性分析

氧还原反应(ORR)是燃料电池性能的关键瓶颈。迄今为止,用于该反应的最活跃和最稳定的电催化剂是基于 Pt 族金属的。过渡金属氧化物 (TMO) 构成了在氧化条件下实现操作稳定性的另一类材料。不幸的是,通常发现 TMO 不如 Pt 活跃。在这里,我们确定了难以找到具有高 ORR 活性的 TMO 的两个原因。首先是 TMO 表面始终比过渡金属更弱地结合氧原子。这使得 O-O 键的断裂决定了此处研究的广泛 TMO 表面的速率。第二个是TMO表面的电场效应更强,这进一步使O-O键断裂变得困难。

更新日期:2021-05-24
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