气凝胶
石墨烯
催化作用
掺杂剂
材料科学
碳纤维
杂原子
纳米技术
化学工程
兴奋剂
化学
有机化学
复合材料
光电子学
复合数
工程类
戒指(化学)
作者
Wei Yu,Limin Liu,Yuxiao Yang,Na Li,Yuzhi Chen,Xiangkai Yin,Jinpen Niu,Jiuhong Wang,Shujiang Ding
标识
DOI:10.1016/j.cej.2023.142787
摘要
Carbon-based metal-free materials are regarded as viable cathode catalysts for Li-CO2 batteries due to their low costs and lightweight. And heteroatom doping (such as N atom) has great potential to improve the catalytic activity of carbon-based catalysts. However, the underlying catalytic mechanism is yet unclear, which hinders the construction of high-efficiency catalysts and further improvements in electrochemical performance. Especially, the role of oxygen-containing groups prevalent in carbon-based catalysts has never been explored. In this work, guided by theoretical simulation, a self-standing N-doped graphene carbon aerogel with certain oxygenic groups was well-designed and synthesized by a straightforward, one-step thermal approach as the cathode catalyst. N dopant can effectively regulate the electronic structure of graphene and thus lower the free energy change of reactants/intermediate species. The intrinsic oxygen-containing functional groups still presented in graphene aerogel can further stabilize CO2-related intermediate species and improve the catalytic activity through a synergistic coupling effect with N dopant. This effect was originally discovered and clarified in the Li-CO2 battery system. Additionally, intriguing 3D hierarchical pores of as-obtained graphene carbon aerogel not only guarantee good conductivity but also offer a vast surface area to expose numerous accessible active sites. The resulting Li-CO2 batteries showed a significantly enhanced initial energy efficiency of approximately 78.46% and remarkable cyclic stability of more than 1500 h at 20 μA cm−2. This fundamental understanding of the structure-performance relationship gives new ideas for creating extremely effective carbon-based metal-free catalysts for Li-CO2 batteries.
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