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Highly Stable Two-Dimensional Iron Monocarbide with Planar Hypercoordinate Moiety and Superior Li-Ion Storage Performance.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-05-12 , DOI: 10.1021/acsami.0c03764
Dong Fan 1 , Chengke Chen 1 , Shaohua Lu 1 , Xiao Li 1 , Meiyan Jiang 1 , Xiaojun Hu 1
Affiliation  

Stable planar hypercoordinate motifs have been recently demonstrated in two-dimensional (2D) confinement systems, while perfectly planar hypercoordinate motifs in 2D carbon–transition metal systems are rarely reported. Here, by using comprehensive ab initio computations, we discover two new iron monocarbide (FeC) binary sheets stabilized at 2D confined space, labeled as tetragonal-FeC (t-FeC) and orthorhombic-FeC (o-FeC), which are energetically more favorable compared with the previously reported square and honeycomb lattices. The proposed t-FeC is the global minimum configuration in the 2D space, and each carbon atom is four-coordinated with four ambient iron atoms, considered as the quasi-planar tetragonal lattice. Strikingly, the o-FeC monolayer is an orthorhombic phase with a perfectly planar pentacoordinate carbon moiety and a planar seven-coordinate iron moiety. These monolayers are the first example of a simultaneously pentacoordinate carbon and planar seven-coordinate Fe-containing material. State-of-the-art theoretical calculations confirm that all these monolayers have significantly dynamic, mechanical, and thermal stabilities. Among these two monolayers, the t-FeC monolayer shows a higher theoretical capacity (395 mAh g–1) and can stably adsorb Li up to t-FeCLi4 (1579 mAh g–1). The low migration energy barrier is predicted as small as 0.26 eV for Li, which results in the fast diffusion of Li atoms on this monolayer, making it a promising candidate for lithium-ion battery material.

中文翻译:

具有平面超坐标部分和出色的锂离子存储性能的高度稳定的二维碳一铁。

最近在二维(2D)约束系统中已经证明了稳定的平面超坐标基元,而在二维碳-过渡金属系统中完美平面的超坐标基元却鲜有报道。在这里,通过使用全面的从头算计算中,我们发现了两个新的稳定在二维密闭空间中的单碳化铁(FeC)二元板,分别标记为四方FeC(t-FeC)和正交晶体FeC(o-FeC),与先前报道的正方形相比,在能量上更有利和蜂窝格子。拟议的t-FeC是二维空间中的全局最小构型,每个碳原子与四个周围的铁原子四配位,被视为准平面四方晶格。令人惊讶的是,o-FeC单层是正交晶相,具有完美平面的五配位碳部分和平面的七配位铁部分。这些单层是同时五配位碳和平面七配位含铁材料的第一个实例。最新的理论计算证实,所有这些单分子层均具有显着的动态,机械和热稳定性。在这两个单层中,t-FeC单层显示出更高的理论容量(395 mAh g–1),并且可以稳定地吸附直至t-FeCLi 4(1579 mAh g –1)的锂。锂的低迁移能垒预计低至0.26 eV,这将导致锂原子在该单层上快速扩散,使其成为锂离子电池材料的有希望的候选者。
更新日期:2020-07-08
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