BEDIAKO LAB
ELECTROCHEMISTRY OF 2D LAYERS | 2D MAGNETISM | TWISTRONICS
Motivation and Summary
If humanity is to profoundly alter its environmental footprint in the twenty-first century, it is imperative to meet the challenge of escalating global energy demand with the innovation of unprecedentedly efficient renewable energy conversion and storage systems. However, our accelerating reliance on information and communication technology also mandates technologically disruptive scientific breakthroughs that allow electronic, communication, and computing devices to operate at orders of magnitude lower energy consumption. These era-defining problems can only be truly solved by a new fundamental understanding of how to control matter to eliminate energy loss in the movement and manipulation of charge.
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Our research group designs and synthesizes new atomically-thin, precisely tailored two-dimensional (2D) materials in which the collective behavior of electrons can be studied and exquisitely controlled. We leverage these materials to uncover the principles that underlie efficient manipulation of electron transport and spin–spin interactions within solids—the basis for novel ultralow-power electronic devices—and electron transfer across solid–liquid interfaces—enabling the next-generation of electrochemical systems for renewable energy conversion and storage.
Research Areas
The invention of modular materials that are amenable to deterministic, atomically precise manipulation is a pre-requisite for transformative advances in both electronic/computing and energy conversion technologies. Our research program sits at the nexus of solid-state inorganic chemistry, condensed matter physics, and electrochemistry. Applying insights and approaches from these fields, we aim to make and measure materials that unlock new directions in the study of collective electronic phenomena and in the manipulation of interfacial reactivity. A unifying theme of our work is a focus on atomically thin materials based on van der Waals (vdW) layered solids. By leveraging degrees of freedom that are unique to these so-called “two-dimensional” (2D) materials, we tailor the physics of surfaces to manipulate electrochemical reactions at solid–liquid interfaces, and we develop chemical/synthetic approaches for engineering many-body electronic interactions in 2D solids.
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So far, we have worked along three primary thrusts that highlight our broad interests in both the physical and chemical ramifications of structural/chemical perturbations to 2D materials:
1) Measuring strain and lattice relaxation in 2D heterostructures,
2) Manipulating interfacial electrochemistry with deterministically assembled atomic heterostructures, and
3) Synthesizing transition metal dichalcogenides that harbor exotic magnetic and charge ordered phases.
In each area, our program has worked to pioneer new types of measurements, demonstrate novel phenomena in previously discovered materials, and/or synthesize new materials that have deepened our understanding of structure–property relationships in inorganic quantum materials. Short summaries of these areas are provided below, with full details available in our Publications.
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Mapping moiré superlattice relaxation
Imposing an azimuthal misorientation between atomic layers to form moiré superlattices leads to exotic physical properties like unconventional superconductivity and a host of other correlated electron physics. Our group is developing electron microscopy methodologies based on four-dimensional scanning transmission electron microscopy (4D-STEM) to provide direct and quantitative measurements of lattice relaxation in moiré superlattices. These 4D-STEM studies have helped to deepen our understanding of relaxation mechanisms and their impact on electronic properties.
Representative publications:
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"Strain fields in twisted bilayer graphene" Kazmierczak, N.P.;º Van Winkle, M.;º Ophus, C.; Bustillo, K. C.; Carr, S.; Brown, H. B.; Ciston, J.; Taniguchi, T.; Watanabe, K.; Bediako, D. K.*Nature Materials 2021, 20, 956–963.
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"Rotational and dilational reconstruction in transition metal dichalcogenide moiré bilayers" Van Winkle, M.;º Craig, I. M.;º Carr, S.; Dandu, M.; Bustillo, K.; Ciston, J.; Ophus, C.; Taniguchi, T.; Watanabe, K.; Griffin, S.; Bediako, D. K.* Nature Communications 2023, 14, 2989.
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"Local atomic stacking and symmetry in twisted graphene trilayers" Craig, I. M.; Van Winkle, M.; Groschner, C.; Zhang, K.; Dowlatshahi, N.; Zhu, Z.; Taniguchi, T.; Watanabe, K.; Griffin, S. M.; Bediako, D. K.* Nature Materials 2024, DOI: 10.1038/s41563-023-01783-y.
2D heterostructures for interfacial charge transfer
Manipulating electron transfer (ET) dynamics across solid–liquid interfaces is fundamental to the interconversion of electrical and chemical energy. We are designing new types of electrode materials based on deterministically assembled 2D layers, inventing distinctive vdW heterostructure platforms that open new possibilities for tailoring interfacial (electro)chemistry through the control over electronic localization at topological defects.
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Representative publications:
Magnetic and charge ordered phases in transition metal dichalcogenides
Transition metal dichalcogenide (TMD) heterostructures can host complex magnetic and charge order. Our group is devising new topotactic strategies to synthesize two dimensional magnetic materials, investigating the impact of disorder on exotic magnetism in intercalated TMDs, and synthesizing heterostructures with well-defined interfaces and controllable phase transitions.
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Representative publications:
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