Effect of Microstructure of Nitrogen-Doped Graphene on Oxygen Reduction Activity in Fuel Cells
Effect of Microstructure of Nitrogen-Doped Graphene on Oxygen Reduction Activity in Fuel Cells
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DOI：
10.1021/la2043262
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发表时间：
2012-05-15
期刊：
影响因子：
3.9
通讯作者：
Xia, Zhenhai
中科院分区：
文献类型：
--
作者：
Zhang, Lipeng;Niu, Jianbing;Xia, Zhenhai
燃料电池作为清洁能源技术的发展在很大程度上受到燃料电池中催化氧还原反应（ORR）所需的贵金属催化剂成本过高的限制。对催化剂设计原理的基本理解将材料结构与催化活性联系起来，可以加速寻找高活性和丰富的非金属催化剂来取代铂。在这里，我们提出了在酸性环境下氮掺杂石墨烯的ORR第一性原理研究。我们证明了ORR活性主要与石墨烯的电荷和自旋密度相关。氮掺杂和缺陷引入了高正自旋和/或电荷密度，促进了石墨烯表面的ORR。所确定的活性位点与掺杂簇大小和掺杂-缺陷相互作用密切相关。一般来说，较大的掺杂簇尺寸（N原子数>2）会减少每个N原子的催化活性位点数。结合N聚类，Stone-Wales缺陷能强烈促进ORB。对于四电子转移，根据缺陷和簇大小的不同，有效可逆电位范围为1.04 ~ 1.15 V/SHE。通过结合材料缺陷引入小N簇可以优化石墨烯的催化性能。
The development of fuel cells as clean-energy technologies is largely limited by the prohibitive cost of the noble-metal catalysts needed for catalyzing the oxygen reduction reaction (ORR) in fuel cells. A fundamental understanding of catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant nonmetal catalysts to replace platinum. Here, we present a first-principles study of ORR on nitrogen-doped graphene in acidic environment. We demonstrate that the ORR activity primarily correlates to charge and spin densities of the graphene. The nitrogen doping and defects introduce high positive spin and/or charge densities that facilitate the ORR on graphene surface. The identified active sites are closely related to doping cluster size and dopant-defect interactions. Generally speaking, a large doping cluster size (number of N atoms >2) reduces the number of catalytic active sites per N atom. In combination with N clustering, Stone-Wales defects can strongly promote ORB.. For four-electron transfer, the effective reversible potential ranges from 1.04 to 1.15 V/SHE, depending on the defects and cluster size. The catalytic properties of graphene could be optimized by introducing small N clusters in combination with material defects.