Collaborative Research: High-resolution electrochemical and Correlated microscopic characterization of 2D electrocatalysts

纽约市立大学皇后学院的Michael Mirkin教授和加州大学欧文分校的Huolin Xin教授得到化学系化学催化计划的支持，研究二维材料，例如过渡金属硫属化物的平面纳米片作为电催化剂，用于加速从水中电催化制氢。 所获得的知识适用于与替代能源生产和储存技术有关的其他重要化学反应。 该项目旨在开发一种独特的显微镜技术，可以对反应部位进行高分辨率成像。 这种成像使用两种技术进行：透射电子显微镜（用于原子尺度的结构信息）和扫描电化学显微镜（用于电化学信息）。 将两种互补技术的数据关联起来提供了关于催化纳米片边缘、缺陷和原子台阶的性质的信息。 需要这些信息来了解这些材料的催化活性。 该项目为各类学生提供可再生能源相关科学和技术方面的培训，包括数学建模和数据处理与挖掘。 地区中学生通过在调查人员实验室的亲身体验接触科学研究。这项合作研究的首要目标是通过高分辨率（即，等于或小于10 nm）反应性作图。 通过使用非常小的纳米电极探针并显着提高SECM分辨率，研究人员绘制并定量测量2D电催化剂上纳米片边缘，缺陷和原子台阶的活动，并评估相变和表面功能化的影响。 该方法是开发多技术成像的催化表面的相同的纳米级部分，以获得空间分辨的机械信息的非均相过程的二维电催化剂。 活性位点的性质是通过将SECM活性图与通过STEM和空间分辨电子能量损失谱（STEM-EELS）获得的原子尺度结构和键合信息一一对应来阐明的。 这些方法研究了两类重要的2D材料-过渡金属二硫属化物和MXene。该研究项目的目的是促进对影响二维电催化剂活性/稳定性的因素的理解，并帮助提出改善这些性能的新策略。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Professor Michael Mirkin of CUNY Queens College and Professor Huolin Xin of the University of California-Irvine are supported by the Chemical Catalysis Program of the Division of Chemistry to study two-dimensional materials, such as flat nanosheets of transition metal chalcogenides as electrocatalysts for speeding up the electrocatalytic production of hydrogen from water. The knowledge obtained is applicable to other important chemical reactions relevant to alternative energy production and storage technologies. The project seeks to develop a unique microscopy technique that allows for the high-resolution imaging of the reactive site. This imaging is conducted using two techniques: transmission electron microscopy (for atomic-scale structural information) and scanning electrochemical microscopy (for electrochemical information). Correlating the data of the two complementary techniques provides information on the nature of the catalytic nanosheet edges, defects and atomic steps. The information is needed to understand the catalytic activity of these materials. The project provides training for a diverse group of students in renewable energy related science and technology, including mathematical modeling and data processing and mining. Area middle school students are exposed to science research through hand-on experience in the investigators' laboratories. The overarching goal of this collaborative research is to visualize and quantify active sites on two-dimensional (2D) catalyst surfaces via high-resolution (i.e., equal or less than 10 nm) reactivity mapping by scanning electrochemical microscopy (SECM) in combination with scanning transmission electron microscopy (STEM) techniques. By using very small nanoelectrode probes and significantly increasing the SECM resolution the researchers map and quantitatively measure activities of the nanosheet edges, defects and atomic steps on 2D electrocatalysts and assess the effects of phase transformations and surface functionalization. The methodology is developed for multi-technique imaging of the same nanoscale portion of the catalytic surface to obtain spatially resolved mechanistic information about heterogeneous processes on 2D electrocatalysts. The nature of the active sites is elucidated by correlating the SECM activity maps with atomic scale structural and bonding information obtained by STEM and spatially resolved electron energy loss spectroscopy (STEM-EELS) with one-to-one correspondence. These approaches investigate two important classes of 2D materials - transition metal dichalcogenides and MXenes. The objective of the research project is to advance the understanding of factors influencing the activity/stability of 2D electrocatalysts and to help put forward new strategies for improving these properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.