Atomic-Layer Dependent Adhesion of Two-Dimensional Transitional Metal Carbides (MXenes)

一个新的大家族的低维材料，2D过渡金属碳化物（MXene），已显示出优异的电子和光学性能，往往是上级相比，其他二维材料。重要的是，与其他2D材料相比，这些特性可以在同一家族中系统地变化和研究，而不会改变材料中的元素组成和原子间键的类型。这些独特的功能使MXenes对基础科学和应用开发同样感兴趣，它们可以用于新的平面和柔性器件，从而产生新技术和重大的经济影响。目前正在研究的一些应用包括健康监测传感器、高性能能量收集和存储系统以及化学光热癌症治疗。然而，MXenes的粘附性，这在许多这些应用中是至关重要的，尚未得到系统的研究。到目前为止，只有很少的理论研究MXenes的粘合行为，很少或没有实验数据。从更广泛的意义上说，实验测定MXenes的粘附性能将有助于我们理解低维材料的粘附和原子结构之间的基本关系。这可能会彻底改变现代材料和制造业，利用低维材料制成的涂层和平面器件的粘附力。该项目的目标是：（i）在原子、纳米和微米尺度上系统地研究MXene的粘附相互作用，（ii）利用MXene提供的独特优势，系统地分别考察了二维材料表面官能团和单层厚度对其粘附相互作用的影响，以及（iii）探索环境对MXenes粘附的影响，包括表面水和氧化过程。为实现这些目标，我们打算：（1）利用基于原子尺度接触的实验来研究原子结构和表面终止对粘附的影响，（2）利用纳米压痕来理解MXene与其自身和其它材料的界面牵引-分离关系，（3）探索原位纳米剪切滞后实验的潜在用途来研究MXene的剪切相互作用，（4）结合联合收割机的多尺度模拟和实验结果，研究了表面缺陷、终端、单层厚度以及（5）探索地表水和氧化过程对MXenes附着力的影响的可能评估。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的评估来支持。影响审查标准。

A novel large family of low dimensional materials, 2D transition metal carbides (MXenes), have shown excellent electronic and optical properties that are often superior compared to other 2D materials. Importantly and in contrast to other 2D materials, these properties can be systematically varied and studied within the same family, without changing elemental composition and type of interatomic bonds in the material. These unique features make MXenes equally interesting for fundamental science and application development, where they can be used in new planar and flexible devices, leading to new technologies and significant economic impacts. Some of these applications that are researched now include health monitoring sensors, high performance energy harvesting and storage systems, and chemo-photothermal cancer therapy. However, the adhesion of MXenes, which is critical in many of these applications, has yet to be systematically investigated. To date, there have only been a few theoretical studies of the adhesive behavior of MXenes, with little to no experimental data. In a broader sense, experimental determination of adhesive properties of MXenes will contribute to our understanding of the fundamental relationships between adhesion and atomic structures for low dimensional materials. This could revolutionize the modern materials and manufacturing industries in harnessing the adhesion for coatings and planar devices made of low dimensional materials.The goals of the project are to: (i) systematically investigate the adhesive interactions of MXenes at the atomistic, nano- and micrometer scales, (ii) using the unique advantages provided by MXenes, systematically and separately examine the effects of surface functional groups and monolayer thickness of 2D materials on their adhesive interactions, and (iii) explore the environmental effects on the adhesion of MXenes including surface water and oxidation process. To achieve the goals, we intend to: (1) utilize the atomistic scale contact-based experiments to investigate the effect of atomic structures and surface terminations on the adhesion, (2) employ nanoindentation to understand the interfacial traction-separation relations of MXenes with themselves and other materials, (3) explore the potential use of in-situ nano-shear-lag experiments to investigate the shear interactions of MXenes, (4) combine the multiscale modeling and the experimental results to understand the coupled adhesive mechanisms involving the surface defects, terminations, monolayer thickness, and (5) explore the possible evaluation of the effects of surface water and oxidation process on the adhesion of MXenes.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.