Hyperbolic enhancement of photocurrent patterns in minimally twisted bilayer graphene

Sunku, Sai; Halbertal, Dorri; Stauber, T.; Chen, S.; McLeod, Alexander; Rikhter, Andrey; Berkowitz, Michael; Lo, Chiu Fan Bowen; Gonzalez-Acevedo, Derick; Hone, James; Dean, Cory; Fogler, M. M.; Basov, D. N.

doi:10.1038/s41467-021-21792-2

Cited by 45 publications

(34 citation statements)

References 38 publications

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“…The tip acts as an antenna and concentrates the incident infrared field at the tip apex, yielding local infrared spectra with spatial resolution determined by the tip radius. On the above basis, nanoFTIR spectroscopy enables reliable probing and mapping of nanoscale chemical composition, and has been applied on the study of single membrane proteins 50 , multi-component polymer blends 51 , and coexisting nanoscale phases 52 , 53 , however has not previously been used to map the compartmentalized multi-enzymes.…”

Section: Introductionmentioning

confidence: 99%

Hierarchically encapsulating enzymes with multi-shelled metal-organic frameworks for tandem biocatalytic reactions

et al. 2022

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Biocatalytic transformations in living organisms, such as multi-enzyme catalytic cascades, proceed in different cellular membrane-compartmentalized organelles with high efficiency. Nevertheless, it remains challenging to mimicking biocatalytic cascade processes in natural systems. Herein, we demonstrate that multi-shelled metal-organic frameworks (MOFs) can be used as a hierarchical scaffold to spatially organize enzymes on nanoscale to enhance cascade catalytic efficiency. Encapsulating multi-enzymes with multi-shelled MOFs by epitaxial shell-by-shell overgrowth leads to 5.8~13.5-fold enhancements in catalytic efficiencies compared with free enzymes in solution. Importantly, multi-shelled MOFs can act as a multi-spatial-compartmental nanoreactor that allows physically compartmentalize multiple enzymes in a single MOF nanoparticle for operating incompatible tandem biocatalytic reaction in one pot. Additionally, we use nanoscale Fourier transform infrared (nano-FTIR) spectroscopy to resolve nanoscale heterogeneity of vibrational activity associated to enzymes encapsulated in multi-shelled MOFs. Furthermore, multi-shelled MOFs enable facile control of multi-enzyme positions according to specific tandem reaction routes, in which close positioning of enzyme-1-loaded and enzyme-2-loaded shells along the inner-to-outer shells could effectively facilitate mass transportation to promote efficient tandem biocatalytic reaction. This work is anticipated to shed new light on designing efficient multi-enzyme catalytic cascades to encourage applications in many chemical and pharmaceutical industrial processes.

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Section: Introductionmentioning

confidence: 99%

Hierarchically encapsulating enzymes with multi-shelled metal-organic frameworks for tandem biocatalytic reactions

et al. 2022

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“…Our work should thus motivate further near-field photocurrent studies on related moiré superlattices including twisted transition metal dichalcogenides 9 and small-angle twisted bilayer graphene. In the course of preparing this manuscript, we became aware of related work 56 .…”

Section: Discussionmentioning

confidence: 99%

Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene

et al. 2021

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Graphene-based moiré superlattices have recently emerged as a unique class of tuneable solid-state systems that exhibit significant optoelectronic activity. Local probing at length scales of the superlattice should provide deeper insight into the microscopic mechanisms of photoresponse and the exact role of the moiré lattice. Here, we employ a nanoscale probe to study photoresponse within a single moiré unit cell of minimally twisted bilayer graphene. Our measurements reveal a spatially rich photoresponse, whose sign and magnitude are governed by the fine structure of the moiré lattice and its orientation with respect to measurement contacts. This results in a strong directional effect and a striking spatial dependence of the gate-voltage response within the moiré domains. The spatial profile and carrier-density dependence of the measured photocurrent point towards a photo-thermoelectric induced response that is further corroborated by good agreement with numerical simulations. Our work shows sub-diffraction photocurrent spectroscopy is an exceptional tool for uncovering the optoelectronic properties of moiré superlattices.

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“…Figure 4 (A-D) shows the results of nano-photocurrent experiments (38) at different 𝑉 𝑡𝑔 . As 𝑉 𝑡𝑔 is increased from zero, the nano-photocurrent begins to resemble the photocurrent profiles seen in other twisted BLG heterostructures (39,40) and are known to arise from domain walls. These results suggest that even though plasmonic effects in the MLG top gate obscure the underlying graphene layer in nano-infrared experiments, nanophotocurrent experiments can be performed successfully.…”

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confidence: 80%

Dual-Gated Graphene Devices for Near-Field Nano-imaging

et al. 2021

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Graphene-based heterostructures display a variety of phenomena that are strongly tunable by electrostatic local gates. Monolayer graphene (MLG) exhibits tunable surface plasmon polaritons, as revealed by scanning nano-infrared experiments. In bilayer graphene (BLG), an electronic gap is induced by a perpendicular displacement field. Gapped BLG is predicted to display unusual effects such as plasmon amplification and domain wall plasmons with significantly larger lifetime than MLG. Furthermore, a variety of correlated electronic phases highly sensitive to displacement fields have been observed in twisted graphene structures. However, applying perpendicular displacement fields in nano-infrared experiments has only recently become possible (1). In this work, we fully characterize two approaches to realizing nano-optics compatible top-gates: bilayer MoS2 and MLG. We perform nano-infrared imaging on both types of structures and evaluate their strengths and weaknesses. Our work paves the way for comprehensive near-field experiments of correlated phenomena and plasmonic effects in graphene-based heterostructures.

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Hyperbolic enhancement of photocurrent patterns in minimally twisted bilayer graphene

Cited by 45 publications

References 38 publications

Hierarchically encapsulating enzymes with multi-shelled metal-organic frameworks for tandem biocatalytic reactions

Hierarchically encapsulating enzymes with multi-shelled metal-organic frameworks for tandem biocatalytic reactions

Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene

Dual-Gated Graphene Devices for Near-Field Nano-imaging

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