García-Romeral Néstor, Keyhanian Masoomeh, Morales-García Ángel, Illas Francesc
Departament de Ciència de Materials i Química Física, Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona c/Martí i Franquès 1-11 08028 Barcelona Spain
Department of Physical Chemistry, Faculty of Chemistry, University of Mazandaran Babolsar 47416-95447 Iran.
Nanoscale Adv. 2021 Mar 1;3(10):2793-2801. doi: 10.1039/d0na01033b. eCollection 2021 May 18.
The relationship between core level binding energy shifts (ΔCLBEs), that can be experimentally determined by X-ray photoelectron spectroscopy, and chemical bonding is analyzed for a series of MXenes, a new family of two-dimensional materials with a broad number of applications in nanotechnology. Based on first-principles calculations, the atomic and electronic structure of bare and O-terminated carbide MXene with MC and MCO (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) stoichiometries are investigated with a focus on trends in the C(1s) and O(1s) ΔCLBEs, including initial and final state effects, along with the series. A rather good linear correlation between the available experimental and calculated C(1s) and O(1s) ΔCLBEs exists, with quantitative agreement when final state effects are included, that validates the conclusions from the present computational approach. The present study shows that ΔCLBEs of bare MXenes are governed by the initial state effects and directly correlate with the net charge on the C atoms. However, for the case of O-terminated MXenes, C(1s) and O(1s) ΔCLBEs exhibit a much less significant correlation with the net charge of either C or O atoms which is attributed to the structural changes induced on the MC moiety by the presence of the O layers and the different stacking sequence observed depending on the MXene composition. The present study shows how and when XPS can be used to extract information regarding the nature of the chemical bond in bare or functionalized MXenes.
通过X射线光电子能谱可以实验测定的芯能级结合能位移（ΔCLBEs）与化学键之间的关系，针对一系列MXenes进行了分析，MXenes是一类新型二维材料，在纳米技术中有广泛应用。基于第一性原理计算，研究了具有MC和MCO（M = Ti、Zr、Hf、V、Nb、Ta、Cr、Mo和W）化学计量比的裸露和O端基碳化MXene的原子和电子结构，重点关注C(1s)和O(1s) ΔCLBEs的趋势，包括初始态和终态效应，以及整个系列的情况。可用的实验和计算得到的C(1s)和O(1s) ΔCLBEs之间存在相当好的线性相关性，当包括终态效应时具有定量一致性，这验证了本计算方法得出的结论。本研究表明，裸露MXenes的ΔCLBEs受初始态效应支配，并且与C原子上的净电荷直接相关。然而，对于O端基MXenes的情况，C(1s)和O(1s) ΔCLBEs与C或O原子的净电荷之间的相关性要小得多，这归因于O层的存在对MC部分引起的结构变化以及根据MXene组成观察到的不同堆积顺序。本研究展示了如何以及何时可以使用XPS来提取有关裸露或功能化MXenes中化学键性质的信息。
