Synthesis and Optoelectronic Properties of Solid Solution MXenes

非技术描述：MXenes是一大类二维碳化物和氮化物，具有优异的电子、光学和电荷存储性能。它们是十年前在德雷塞尔大学发现的。MXenes由由碳原子或氮原子连接的金属原子层组成，厚度小于1纳米。它们独特的结合了电子导电性和可调谐的光学特性，如广泛的等离子体颜色，可能会改变光学和电子学的游戏规则。目前已经合成了30多种不同的MXene组合物；预计还会有数十种。然而，尽管MXenes上的出版物总数接近3000，但只有少数固溶体（金属原子随机混合的结构）被报道。本研究中合成的固溶体MXenes极大地扩展了二维（2D）材料家族，并为MXenes的电子和光学特性的精确调谐提供了机会。这些材料可以用于制造太阳能电池的透明导电电极、智能窗户、透明加热器、光学滤波器等。课程涵盖了MXenes的合成和表征作为这个项目的一部分，并在网上提供。参与该项目的研究生和本科生将在韩国国家纳米制造设施进行研究合作教育和实习，学习纳米制造，并进行基于mxene的光学器件的制造和测试，如透明发光二极管和电可调谐滤光片。技术细节：本工作的主要目标是建立固溶体MXene的化学组成与其产生的性质之间的直接实验关系。固溶体MXene研究扩展到不同的结构和化学，以研究和推广这些关系，从而使特定的光学和等离子体特性能够根据所需的应用合理选择。该项目包括(i)合成具有所需成分的四元MAX相前驱体；（ii）寻找将MAX前体拓扑化学转化为MXenes的适当条件，（iii）确定MXenes的电导率和光学性质，以及（iv）使用一系列先进的表征技术确定固溶体MXenes的组成和结构，并将它们与测量的性质相关联。该奖项反映了美国国家科学基金会的法定使命，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。

NON-TECHNICAL DESCRIPTION: MXenes are a large class of two-dimensional carbides and nitrides that exhibit exceptional electronic, optical and charge storage properties. They were discovered at Drexel University a decade ago. MXenes are comprised of layers of metal atoms connected by carbon or nitrogen atoms and having thickness of less than one nanometer. Their unique combination of electronic conductivity and tunable optical properties, such as a wide range of plasmonic colors, may be a game-changer in optics and electronics. More than 30 different MXene compositions have been synthesized; dozens more are predicted to exist. However, in spite of total number of publications on MXenes approaching 3000, just a few solid solutions (structures with a random mix of metal atoms) have been reported. Solid solution MXenes that are synthesized in this study greatly expand the family of two-dimensional (2D) materials and offer an opportunity for precise tuning of electronic and optical properties of MXenes. These materials can find applications in the manufacturing of transparent conductive electrodes for solar cells, smart windows, transparent heaters, optical filters, etc. Courses covering synthesis and characterization of MXenes are developed as a part of this project and offered online. Graduate and undergraduate students participating in this project are offered research co-operative education and internships at the National Nanofabrication Facility in South Korea to learn nanofabrication and perform fabrication and testing of MXene-based optical devices, such as transparent light emission diodes and electrically tunable optical filters. TECHNICAL DETAILS: The primary goal of this work is to establish direct experimental relationships between chemical compositions of solid solution MXene and their resulting properties. Solid solution MXene research is expanded into diverse structures and chemistries in order to study and generalize these relationships, and thus to enable specific optical and plasmonic properties to be rationally chosen based on the desired application. This project includes (i) synthesis of quaternary MAX phase precursors with the desired compositions; (ii) finding the appropriate conditions for topochemical conversion of the MAX precursors into MXenes, (iii) determining the conductivity and optical properties of MXenes, and (iv) using an array of advanced characterization techniques to determine the composition and structure of solid-solution MXenes and correlate them with the measured 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.