Dual-site oxygen reduction reaction mechanism on CoN4 and CoN2 embedded graphene: Theoretical insights
Dual-site oxygen reduction reaction mechanism on CoN4 and CoN2 embedded graphene: Theoretical insights
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CoN4和CoN2嵌入石墨烯上的双位点氧还原反应机制：理论见解
DOI：
10.1016/j.carbon.2016.07.051
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发表时间：
2016-11
期刊：
影响因子：
10.9
通讯作者：
Wu Zhijian
中科院分区：
文献类型：
--
作者：
Sun Xiaoxu;Li Kai;Yin Cong;Wang Ying;Jiao Menggai;He Feng;Bai Xiaowan;Tang Hao;Wu Zhijian
作为潜在的电催化剂候选材料之一，非贵金属氮嵌入石墨烯近年来受到了广泛的关注。深入了解氧还原反应机理，包括特定的活性位点和反应途径，将有助于进一步提高其催化活性。采用密度泛函方法研究了CoN2和CoN4嵌入石墨烯在酸性介质中的ORR过程.生成能的计算结果表明，CoN2和CoN4嵌入的石墨烯均为热力学稳定构型.在CoN4位上，形成HOOH的反应途径是最有利的途径。然而，CoN4位点不促进完全ORR，并且HOOH是最终产物。同时，对于CoN2嵌入的石墨烯，HOOH解离的反应途径也是最有利的反应途径，其反应速度决定步骤的能垒为0.58 eV.这意味着CoN2位点充当CoNx嵌入的石墨烯上的完整ORR的第二位点。因此，在CoN4位上形成的HOOH可以在CoN2位上解离，导致双位2 × 2e−ORR机制。最后讨论了不同电极电位对ORR的影响。
As one of the potential candidates of electrocatalysts, non-precious transition metal and nitrogen embedded graphene has attracted extensive attention in recent years. Deep understanding of the oxygen reduction reaction (ORR) mechanism including the specific active sites and reaction pathways will contribute to the further enhancement of their catalytic activity. In this work, density functional study is conducted on the ORR process of CoN2and CoN4embedded graphene in acid medium. The calculated formation energy shows that both CoN2and CoN4embedded graphenes are thermodynamically stable configurations. On the CoN4site, the reaction pathway to form HOOH is the most favorable pathway. However, CoN4site does not promote complete ORR and HOOH is the final product. Meanwhile, for CoN2embedded graphene, the reaction pathway of HOOH dissociation is also the most favorable pathway and the energy barrier is 0.58 eV in the rate-determining step. This implies that CoN2site serves as the second site for the complete ORR on the CoNxembedded graphene. Therefore, the HOOH formed on the CoN4site can be dissociated on the CoN2site, leading to a dual-site 2 × 2e−ORR mechanism. Finally, the effect of different electrode potentials on the ORR is discussed.
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