Adding a New Member to the MXene Family: Synthesis, Structure, and Electrocatalytic Activity for the Hydrogen Evolution Reaction of V4C3Tx
Adding a New Member to the MXene Family: Synthesis, Structure, and Electrocatalytic Activity for the Hydrogen Evolution Reaction of V4C3Tx
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DOI：
10.1021/acsaem.8b00652
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发表时间：
2018-08-01
影响因子：
6.4
通讯作者：
Birkel, Christina S.
中科院分区：
文献类型：
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作者：
Tran, Minh H.;Schaefer, Timo;Birkel, Christina S.
二维过渡金属基碳化物（或氮化物），即所谓的MXenes，可以从三维MAX相中得到，在过去几年中引起了相当大的关注。这种特殊的结构以及它们的亲水性和金属性质使它们成为大量应用的有希望的候选者，如传感器、电极和催化剂。显然，各自的化学和物理性质高度依赖于MXene的化学组成、化学计量和表面结构。在这里，我们介绍了MXene家族的一个新成员，V4C3Tx （T代表表面基团），基于氢氟酸处理413 MAX相V4AlC3的化学剥离。x射线粉末衍射数据和尺度桥接电镜研究证明了铝从MAX相结构中成功去除。在酸性溶液中测试了这种新型MXene的析氢反应的电催化活性，并进行了100次循环。有趣的是，我们发现随着时间的推移，催化性能有了显著的改善（即，达到10毫安厘米（-2）电流密度所需的过电位降低了近200毫伏），我们将其归功于从MXene表面去除氧化物，如XPS测量所示。我们的研究为MXenes的电催化活性及其表面结构的演变提供了关键的实验数据，这也与其他过渡金属基MXenes在进一步潜在应用的背景下相关。
Two-dimensional transition-metal-based carbides (or nitrides), so-called MXenes, that can be derived from the three-dimensional MAX phases, have attracted considerable attention throughout the past couple of years. The particular structure together with their hydrophilic and metallic nature make them promising candidates for a plethora of applications, such as sensors, electrodes, and catalysts. Obviously, the respective chemical and physical properties are highly dependent on the chemical composition, stoichiometry, and surface structure of the MXene. Here, we introduce a new member of the MXene family, V4C3Tx (T representing the surface groups), based on the chemical exfoliation of the 413 MAX phase V4AlC3 by treatment with aqueous hydrofluoric acid. X-ray powder diffraction data together with scale-bridging electron microscopy studies prove the successful removal of aluminum from the MAX phase structure. The electrocatalytic activity for the hydrogen evolution reaction of this new MXene is tested in acidic solution over the course of 100 cycles. Interestingly, we find a significant improvement of the catalytic performance over time (i.e., the overpotential required to achieve a current density of 10 mA cm(-2) decreases by almost 200 mV) that we assign to the removal of an oxide species from the surface of the MXene, as shown by XPS measurements. Our study provides crucial experimental data of the electrocatalytic activity of MXenes together with the evolution of its surface structure that is also relevant for other transition-metal-based MXenes in the context of further potential applications.