Discovering Novel Properties in Few-Layer MXenes Using Analytical, In-Situ Scanning Transmission Electron Microscopy

使用分析原位扫描透射电子显微镜发现少层 MXene 的新特性

• 批准号: 2309396
• 负责人: Robert Klie
• 金额: $ 54.97万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2027-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309396&HistoricalAwards=false
• 关键词: Discovering; Novel; Properties; Few; Layer

NON-TECHNICAL DESCRIPTION: Materials known as MXenes are part of a growing family of two-dimensional structures that have attracted significant research interests due to their wide range of properties. These layered transition metal carbides and nitrides have the chemical formula of Mn+1XnTx (n=1-3), where M is a transition metal, X is either carbon or nitrogen, and Tx is either O, OH, F, Cl, or other surface groups that are bonded to the transition metal of the two-dimensional MXene layer. This project focuses on developing an atomic-scale understanding of the optical properties of MXenes, including their tunable plasmon resonances in the visible and near-infrared regime, which can be used for applications in nano-photonics or plasmonics. It is the PI’s hypothesis that different functional groups, Tx, control not only the layer-to-layer spacings of the two-dimensional MXene layers, but also provide the ability to tune the interactions between MXene layers as well as the density of free charges in each layer. Ti3C2 and Ti2C-based MXenes with a single type of surface termination will be used to study the atomic, electronic and plasmonic structures high-resolution electron microscopy and spectroscopy. Access to unique instrumentation at University of Illinois - Chicago (UIC) will be leveraged to study these materials over a wide range of temperatures and with unprecedented spatial and energy resolution. The project’s research activities center around hands-on research and learning experiences for science and engineering undergraduate and graduate students at the UIC, a Research-1 Hispanic-serving institution. Recruitment and training focuses on the next generation of researchers, in particular involving students from underrepresented groups and minorities through a student exchange program with Tecnologico de Monterrey, Latin@s Gaining Access to Networks for Advancement in Science and the DuSable Scholars programs. The participation of undergraduate students in active research projects is fostered through the PI’s Journal of Undergraduate Research at the University of Illinois - Chicago. Graduates of this program will contribute to academia, National Laboratories or industry, including semiconductor companies.TECHNICAL DESCRIPTION: The objectives of this research project are to develop an atomic-scale understanding of the nano-photonic and plasmonic properties of Ti3C2Tx and Ti2CTx MXenes, functionalized with a single, well-controlled species, using atomic-resolution scanning transmission electron microscopy (STEM) imaging, conventional and monochromated electron energy loss spectroscopy (EELS) combined with in-situ cooling to liquid nitrogen temperatures. Twisted bi-layer MXenes exhibiting Moiré lattice effects will be studied for the emergence of hybridized plasmons or excitons, as well as other emerging, potentially strongly correlated phenomena. Using autonomous anomaly detection in multi-dimensional data cubes via machine learning (ML), the correlation between structural defects and their impact on the plasmonic and photonic properties will be studied. This research project will consist of two tasks, i) atomic-resolution analysis of MXenes and ii) development of convolutional neural networks to identify crystal defects in atomic-resolution STEM images and identify the correlated changes in the low-loss or valence EELS. The insights from both tasks will be combined, yielding the ability to measure and control the optical or electronic, and possibly even magnetic properties of single-functionalized MXenes. The integration of research and education through the training of undergraduate and graduate students in state-of-the-art in-situ scanning transmission electron microscopy and state-of-the-art ML approaches is an integral feature of this project.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.

非技术描述：被称为 MXene 的材料是不断增长的二维结构家族的一部分，由于其广泛的特性而引起了人们的广泛研究兴趣，这些层状过渡金属碳化物和氮化物的化学式为 Mn+1XnTx（ n=1-3)，其中M是过渡金属，X是碳或氮，Tx是O、OH、F、Cl或其他键合的表面基团该项目的重点是对 MXene 的光学特性进行原子尺度的理解，包括它们在可见光和近红外区域的可调谐等离子体共振，可用于纳米应用。 -光子学或等离子体激元学。PI 的假设是，不同的官能团 Tx 不仅控制二维 MXene 层的层间间距，而且还提供调整的能力。 MXene 层之间的相互作用以及每层中的自由电荷密度以及具有单一类型表面终止的 Ti3C2 基 MXene 将用于研究原子、电子和等离子体结构的高分辨率电子显微镜和光谱学。该项目的研究活动以实践研究为中心，将利用伊利诺伊大学芝加哥分校 (UIC) 的独特仪器在较宽的温度范围内以前所未有的空间和能量分辨率研究这些材料。 UIC 是一所为 Research-1 西班牙裔服务的机构，为科学与工程本科生和研究生提供学习体验。 招聘和培训重点关注下一代研究人员，特别是通过学生交流计划让来自代表性不足的群体和少数族裔的学生参与其中。 Tecnologico de Monterrey，Latin@s 获得科学进步网络和 DuSable 学者计划 通过 PI 的伊利诺伊大学本科生研究杂志促进本科生参与活跃的研究项目。芝加哥。该项目的毕业生将为学术界、国家实验室或工业界（包括半导体公司）做出贡献。技术描述：该研究项目的目标是在原子尺度上了解 Ti3C2TX 和 Ti2CTx MXene 的纳米光子和等离子体特性。 ，用单一的、控制良好的物质进行功能化，使用原子分辨率扫描透射电子显微镜（STEM）成像，传统的单色电子能量损失光谱（EELS）与原位冷却至液氮温度相结合，将利用自主异常研究表现出莫尔晶格效应的混合等离子体或激子的出现，以及其他新兴的、潜在的强相关现象。通过机器学习（ML）检测多维数据立方体，结构缺陷之间的相关性及其对等离子体和光子特性的影响将被研究该研究项目将包括两个任务， i) MXene 的原子分辨率分析，ii) 开发卷积神经网络，以识别原子分辨率 STEM 图像中的晶体缺陷，并识别低损耗或价态 EELS 的相关变化。这两项任务的见解将被结合起来，产生。测量和控制单功能化 MXene 的光学或电子甚至磁性的能力通过在最先进的原位培训本科生和研究生来实现研究和教育的一体化。扫描透射电子显微镜和最先进的机器学习方法是该项目的一个组成部分。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。