当前位置: X-MOL 学术ACS Catal. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Unconventional Oxygen Reduction Reaction Mechanism and Scaling Relation on Single-Atom Catalysts
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-03-20 , DOI: 10.1021/acscatal.0c00815
Lixiang Zhong 1 , Shuzhou Li 1
Affiliation  

The electrochemical oxygen reduction reaction (ORR) mechanism was generally considered to be O2 → OOH* → O* → OH* → H2O (O* mechanism). This O* mechanism predicted reasonable ORR half-wave potential (E1/2) of Co/N/C but abnormally underestimated the one of Fe/N/C. Herein, we highlight an unconventional 2OH* ORR mechanism (O2 → OOH* → 2OH* → OH* → H2O), which was often ignored because the free energies (ΔG) of 2OH* and O* are equal, according to the famous scaling relation: 2ΔG(OH*) = ΔG(O*). This scaling relation is true for traditional catalysts with near-continuous active sites. We find a different scaling relation: ΔG(2OH*) = ΔG(O*) + 1.5 eV on single-atom catalysts (Me/N/C, Me = Fe, Co, etc.) and suggest that the 2OH* mechanism should not be overlooked. In consideration of both O* and 2OH* mechanisms, the ORR E1/2 values of Co/N/C and Fe/N/C are in good agreement with experimental results. This work reveals the structure dependence of ORR reaction mechanisms and scaling relations in single-atom catalysis, and it is also heuristic for other reactions, such as O2 evolution and N2 reduction on single-atom catalysts.

中文翻译:

单原子催化剂的非常规氧还原反应机理及结垢关系

通常认为电化学氧还原反应(ORR)的机理为O 2  →OOH *→O *→OH *→H 2 O(O *机理)。这种O *机制预测了Co / N / C的合理的ORR半波电势(E 1/2),但异常低估了Fe / N / C的一种。在本文中,我们重点介绍了一种非常规的2OH * ORR机理(O 2  →OOH *→2OH *→OH *→H 2 O),这通常被忽略,因为2OH *和O *的自由能(ΔG)相等。著名的标度关系:2Δ ģ(OH *)=Δ ģ(O *)。这种比例关系对于具有近连续活性位的传统催化剂是正确的。我们发现了不同的比例关系:在单原子催化剂上(Me / N / C,Me = Fe,Co等),ΔG(2OH *)= ΔG(O *)+ 1.5 eV,并建议2OH *机制不容忽视。考虑到O *和2OH *机理,Co / N / C和Fe / N / C的ORR E 1/2值与实验结果非常吻合。这项工作揭示了ORR反应机理的结构依赖性和在单原子催化中的比例关系,对于其他反应,如在单原子催化剂上的O 2析出和N 2还原,也具有启发性。
更新日期:2020-03-21
down
wechat
bug