EAGER: Experimental studies of electrical double-layer capacitance of graphene using van der Waals heterostructures

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Nontechnical:Electrochemical devices based on graphene have shown promise for sensing and energy storage applications. Graphene-based electrochemical transistors have also been demonstrated to record electrical signals in the brain. A major reason for interest in this family of devices is their ease of fabrication and simple operation. New applications using electrochemical devices require dense integration of these devices into large-scale functional systems. This has, however, remained a difficult challenge. It is difficult to maintain high performance and low variability when reducing device dimensions. Advances in nanofabrication make it possible to miniaturize electrochemical devices, but much work still needs to be done to fully understand the underlying physics that governs their operation. This knowledge is essential to enable systematic downscaling of the electrochemical devices. This project will make important progress towards that goal by studying capacitance in a strongly correlated quantum system.Technical:Electrical double-layer capacitance per unit area is a key metric for engineering the performance of miniaturized electrochemical devices. An important new research direction for studying the electrical double-layer capacitance of graphene is to investigate the capacitance per unit area with the aid of graphene electronic band structure. Inspired by this new research direction, the proposed research explores a new paradigm for precise engineering of the electrical double-layer capacitance of miniaturized graphene electrochemical devices. This paradigm involves enhancing the correlation between electrons in graphene and ions in the electrolyte. The research approach in this study is interdisciplinary in that it will use advanced van der Waals graphene heterostructures from quantum physics to explore a longstanding question in electrochemistry. Specifically, van der Waals graphene heterostructures will be used as the test device structure, where the potential profile across graphene will be tuned during the construction of the heterostructure. To study the effect of the potential profile in graphene on the electrical double-layer capacitance, the devices will be electrically characterized using capacitance-voltage and voltammetry measurements. The proposed research project may enable accurate engineering of the capacitance in graphene with nanoscale precision, while revealing a pathway for increasing its achievable value beyond the current limits. This project will also trai of students in important scientific areas and provide them with expertise in device physics, nanofabrication, and analysis methods.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.