Identifying the Active Site of N-Doped Graphene for Oxygen Reduction by Selective Chemical Modification,ACS Energy Letters

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Identifying the Active Site of N-Doped Graphene for Oxygen Reduction by Selective Chemical Modification
ACS Energy Letters ( IF 19.3 ) Pub Date : 2018-03-19 00:00:00 , DOI: 10.1021/acsenergylett.8b00258
Tao Wang ₁ , Zhi-Xin Chen ₁ , Yu-Gang Chen ₂ , Li-Jun Yang ₂ , Xiao-Dong Yang ₃ , Jin-Yu Ye ₁ , Hai-Ping Xia ₁ , Zhi-You Zhou ₁ , Shi-Gang Sun ₁

Affiliation

N-doped carbon materials are promising electrocatalysts for oxygen reduction reaction (ORR). However, the lack of knowledge in the nature of active sites limits the rational design of this type of catalysts. Although pyridinic N species are proposed to be active for ORR, little experimental evidence is provided to reveal the reactive sites. Herein, we developed a surface-modification method to identify the ortho-carbon atom of the pyridinic ring as the reactive site for ORR on N-doped graphene. The pyridinic ring of N-doped graphene was selectively grafted by an acetyl group at pyridinic N and ortho-C atoms by electrophilic and radical substitution, respectively. The former remained most of ORR catalytic activity, while the latter lost its activity completely. DFT calculations confirm that O₂ can get adsorbed and reduced favorably on the ortho-C atom of the pyridinic ring. This study provides new insight into the nature of active sites and the ORR mechanism for N-doped carbon materials.

中文翻译：

通过选择性化学修饰确定N掺杂石墨烯的活性位点以减少氧气

氮掺杂碳材料是用于氧还原反应（ORR）的有前途的电催化剂。但是，缺乏对活性位点性质的了解限制了这种催化剂的合理设计。尽管提出吡啶二氮类物质对ORR具有活性，但很少有实验证据来揭示反应性位点。本文中，我们开发了一种表面修饰方法，以将吡啶环的邻碳原子确定为N掺杂石墨烯上ORR的反应位点。N掺杂石墨烯的吡啶环被吡啶N和邻位的乙酰基选择性接枝-C原子分别通过亲电和自由基取代。前者仍然是ORR的大部分催化活性，而后者则完全失去了活性。DFT计算证实，O ₂可以被吸附并被有利地还原在吡啶环的邻-C原子上。这项研究提供了新的见解，活性位点的性质和氮掺杂碳材料的ORR机制。

更新日期：2018-03-19

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