In-situ visualization of hydrogen evolution sites on helium ion treated molybdenum dichalcogenides under reaction conditions
In-situ visualization of hydrogen evolution sites on helium ion treated molybdenum dichalcogenides under reaction conditions
复制标题
DOI：
10.1038/s41699-019-0107-5
复制
发表时间：
2019-07
影响因子：
9.7
通讯作者：
E. Mitterreiter;Yunchang Liang;Matthias Golibrzuch;David McLaughlin;C. Csoklich;J. Bartl;A. Holleitner-A.-Ho
中科院分区：
文献类型：
--
作者：
E. Mitterreiter;Yunchang Liang;Matthias Golibrzuch;David McLaughlin;C. Csoklich;J. Bartl;A. Holleitner-A.-Ho
纳米结构的二维过渡金属二硫属化合物在多相催化中发挥着越来越重要的作用。这些材料是丰富的（共）催化剂，具有可调的性质，以催化与能量供应相关的许多关键反应，例如析氢反应（HER）。了解哪些表面位点是活性的，以最大限度地增加它们的数量并改善这些材料的整体（光）催化行为是至关重要的。在这里，我们通过电化学扫描隧道显微镜以纳米级的横向分辨率在HER条件下观察了二硫属钼（MoX 2，X = Se，S）表面的这些活性位点。单个MoX2薄片的边缘显示出高的催化活性，而它们的平台是不活跃的。我们演示了如何惰性的这些材料的基面可以被激活的帮助下，聚焦光束的氦离子显微镜对HER。我们的研究结果表明，氦离子诱导的缺陷有助于在较低的过电位HER，而活动的边缘超过足够高的过电位的基础缺陷的活动。由于光刻分辨率的氦离子显微镜，我们的研究结果表明，在过渡金属dichalcogenides产生活性位点的空间分辨率低于几纳米的可能性。
Nanostructured 2D transition metal dichalcogenides play an increasingly important role in heterogeneous catalysis. These materials are abundant (co-)catalysts with tunable properties to catalyze a number of key reactions related to energy provision, for instance the hydrogen evolution reaction (HER). It is vital to understand which surface sites are active in order to maximize their number and to improve the overall (photo-)catalytic behavior of those materials. Here, we visualize these active sites under HER conditions at the surface of molybdenum dichalcogenides (MoX2, X = Se, S) with lateral resolution on the nanometer scale by means of electrochemical scanning tunneling microscopy. The edges of single MoX2flakes show high catalytic activity, whereas their terraces are inactive. We demonstrate how the inert basal planes of these materials can be activated towards the HER with the help of a focused beam of a He-ion microscope. Our findings demonstrate that the He-ion induced defects contribute at lower overpotentials to the HER, while the activity of the edges exceeds the activity of the basal defects for sufficiently high overpotentials. Given the lithographic resolution of the helium ion microscope, our results show the possibility to generate active sites in transition metal dichalcogenides with a spatial resolution below a few nanometers.