Synthesis and applications of dispersible exfoliated metal oxide nanosheets fabricated by ALD

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1034374ParsonsIntellectual MeritThis research addresses the field of vapor-phase low temperature inorganic and organic thin film formation chemistry, to improve fundamental understanding and advance engineered system applications. It will expand fundamental knowledge in the field of low temperature chemical processes for amorphous and polycrystalline thin films, particularly in the field of low temperature atomic layer deposition (ALD). Atomic layer deposition utilizes vapor phase precursors in a binary surface reaction scheme to build up inorganic thin films with monolayer precision in film thickness. Most ALD material applications, including for example commercial high dielectric constant insulators in semiconductor logic devices, require films in excess of ~2 nanometers to achieve functional performance. This work will emphasize ALD growth initiation on receptive low temperature substrates, and explore the ultimate minimum thickness limits for self-cohesive surface-releasable ALD thin films. Research will seek to understand surface reaction mechanisms and substrate interactions during ALD processes to produce viable nano-layered semiconductors that can be released from a substrate and suspended in solution. The PI will also explore the fundamental properties of these materials in comparison with similar known materials formed by layered structure exfoliation, and examine how the new methods and materials can be used for beneficial impact. A particular application focus will be on anisotropic materials for photoelectrochemical water dissociation. This project will build on previous work, and the work on suspended nanosheets will initiate new research in a field that is not currently explored in the ALD or thin film deposition research community. There are several specific challenges, including designing ALD integration schemes and processes for self-cohesive ultrathin materials. The area of exfoliated nanosheets is sufficiently new, and the possible outcomes are sufficiently broad that the fundamental knowledge gained in this study will impact and expand the field of engineering of thin film deposition reactions. Broader ImpactThe project will promote teaching by allowing senior graduate students to mentor BS and more junior PhD students working in the lab. The PI plans to broaden participation by continuing to recruit students from underrepresented groups. The new research will enhance knowledge and research infrastructure in solar photoelectrochemistry, which is a growing area of interest at NC State and in the Research Triangle region in general. Results will be broadly disseminated by the students and PI in peer-reviewed journals and research conferences. The possible outcome of this work in new material processing schemes for economical solar-driven water electrolysis could provide significant beneficial impact to society in terms of energy and environment. The plans to advance basic understanding of ultra-thin film deposition will also impact a wide variety of fields, including advanced electronics, sensor technologies and other energy systems.