Topochemical synthesis of functional 2D materials

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PART 1: NON-TECHNICAL SUMMARYModification of functional materials is one of the greatest challenges facing materials scientists and this tuning is critical for future technological applications. Two dimensional (2D) materials, like graphene, have the potential to unlock new technologies that will lead to smaller, cheaper, faster, and more efficient devices. The long-term goal of this project is to develop new synthetic methods that allow for the modification of more complex, multi-element 2D materials through insertion reactions in which guest atoms and molecules are incorporated without disrupting the original layered structure of the host. The initial aim of this project will focus on layered metal oxyhalide compounds with the short-term goals of understanding what role the host materials play on the insertion reactions and the types of guests that can be inserted. By understanding what governs the insertion reactions, new guests with novel properties can be designed and incorporated into layered materials resulting in products with specific desirable properties. The physical and electronic properties of these materials will be monitored to understand how to fine tune 2D materials for future applications including batteries, smart windows, and ultra-thin electronic components like transistors and capacitors. This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR), will give students from high school through graduate school hands on training and education in the field of materials chemistry. These future scientists will be taught skills in both synthesis and characterization solid state materials as well as the fundamental background on these technologically important materials. The PI will also interact with high school and community college classes through demonstrations and seminars to help educate the general public about the importance of novel layered materials for future applications. PART 2: TECHNICAL SUMMARYThe goal of this project is to develop new synthetic methods to prepare 2D oxyhalide materials with tunable properties and provide a platform for modifying other types of 2D materials through intercalation chemistry. There are several types of layered elements and compounds, but understanding of the chemistry behind their intercalation reactions is limited. This project will focus on the synthesis and characterization -- including optical, electrical, and magnetic properties measurements -- of layered transition metal oxychloride crystals intercalated with multiple guest species including Li, Fe, Co, and Mn. These novel layered materials will be synthesized from their single crystal host metal oxychlorides using solvothermal methods and characterized with electron microscopy, X-ray diffraction, electron paramagnetic resonance, and absorption and photoluminescence spectroscopies. These characterization techniques will help locate and quantify the second metal in the gap between the covalent metal oxide layers and understand how it affects the properties of the host material. The development of these new synthetic methods will lead to a family of novel bimetallic oxychlorides with interesting electronic and magnetic properties. It will also provide a general synthetic method that will enable intercalation of metals beyond alkali and alkaline metals. Finally, the project will use these layered materials as a starting point for exfoliation to produce atomically thin 2D sheets with new fundamental properties due to quantum confinement and enable fine tuning of their properties. This project is supported by the Solid State and Materials Chemistry program in the Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR).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.