Synthesis and Surface Chemistry of 2D TiVC Solid-Solution MXenes
Synthesis and Surface Chemistry of 2D TiVC Solid-Solution MXenes
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DOI：
10.1021/acsami.0c03181
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发表时间：
2020-04-29
影响因子：
9.5
通讯作者：
Brennecka, Geoff L.
中科院分区：
文献类型：
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作者：
Yazdanparast, Sanaz;Soltanmohammad, Sina;Brennecka, Geoff L.
MXene是用于储能应用和超级电容器的新兴二维（2D）材料。它们的表面化学决定了关键的性质，由于不同的合成条件而有所不同。本文采用两种不同的合成方法合成了TiVC固溶体MXene，并对其表面官能团进行了研究。我们使用两种不同的溶液进行TiVAlC MAX相的蚀刻，高浓度的HF（50重量%约为29 M）和LiF和HCl的混合物（1.9 M LiF/12 M HCl）。TiVCTx的大规模脱层以产生单片悬浮液是通过进一步用四丁基氢氧化铵（TBAOH）插层从LiF/HCl得到的MXene来实现的。X射线衍射表明TiVCTx MXene薄片的层间距为2.18 nm。为了研究TiVC MXene上不同官能团的结构稳定性和吸附能，进行了密度泛函理论（DFT）计算并得到X射线光电子能谱（XPS）测量的支持。通过LiF/HCl合成的TiVC上实现了较高浓度的=O和较低浓度的-F，这两者都为储能应用提供了更有利的表面化学。我们的研究结果提供了第一个系统的研究合成条件对固溶体TiVC MXenes的表面化学的影响。
MXenes are emerging two-dimensional (2D) materials for energy-storage applications and supercapacitors. Their surface chemistry, which determines critical properties, varies due to different synthesis conditions. In this work, we synthesized TiVC solid-solution MXenes by two different synthesis methods and investigated their surface functional groups. We performed etching of the TiVAlC MAX phase using two different solutions, a highly concentrated HF (SO wt % approximate to 29 M) and a mixture of LiF and HCl (1.9 M LiF/12 M HCl). Large-scale delamination of TiVCTx to produce single-flake suspension was achieved by further intercalation of the resultant MXene from LiF/HCl with tetrabutylammonium hydroxide (TBAOH). X-ray diffraction indicates a large interlayer spacing of 2.18 nm for TiVCTx MXene flakes. To investigate the structural stability and adsorption energy of different functional groups on TiVC MXenes, density functional theory (DFT) calculations were performed and supported with X-ray photoelectron spectroscopy (XPS) measurements. A higher concentration of =O and a lower concentration of -F were achieved on the TiVC synthesized by LiF/HCl, both of which provide a more favorable surface chemistry for energy-storage applications. Our results provide the first systematic study on the effect of synthesis conditions on the surface chemistry of solid-solution TiVC MXenes.