Single-crystal, large-area, fold-free monolayer graphene

Wang, Meihui; Huang, Ming; Luo, Da; Li, Yunqing; Choe, Myeonggi; Seong, Won Kyung; Kim, Min-Hyeok; Jin, Sunghwan; Wang, Mengran; Chatterjee, Shahana; Kwon, Youngwoo; Lee, Zonghoon; Ruoff, Rodney S.

doi:10.1038/s41586-021-03753-3

Cited by 268 publications

(224 citation statements)

References 35 publications

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“…Our previous growth on homemade single‐crystal Cu–Ni(111) alloy foil with 20.0 at% Ni shows that graphene folds formed in SLG film become narrower and closer to each other when the growth temperature is lower. [ 32 ]…”

Section: Resultsmentioning

confidence: 99%

“…[ 15,27,28 ] In our recent work, we obtained centimeter long parallel graphene folds with relatively uniform widths and spacings between two adjacent folds, by growing single‐crystal graphene on a single‐crystal Cu(111) foil surface. [ 30,32 ] Here, we find that bunched Cu steps along the <110> and <211> directions are formed under graphene, and these Cu steps: i) trigger the formation of the highly oriented “arrays” of folds, and ii) fracture the folds into alternating patterns at step edge regions. The detailed mechanisms about why folds are formed parallel to each other and how and why folds fracture are discussed further below.…”

Section: Introductionmentioning

confidence: 94%

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Folding and Fracture of Single‐Crystal Graphene Grown on a Cu(111) Foil

et al. 2022

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A single‐crystal graphene film grown on a Cu(111) foil by chemical vapor deposition (CVD) has ribbon‐like fold structures. These graphene folds are highly oriented and essentially parallel to each other. Cu surface steps underneath the graphene are along the <110> and <211> directions, leading to the formation of the arrays of folds. The folds in the single‐layer graphene (SLG) are not continuous but break up into alternating patterns. A “joint” (an AB‐stacked bilayer graphene) region connects two neighboring alternating regions, and the breaks are always along zigzag or armchair directions. Folds formed in bilayer or few‐layer graphene are continuous with no breaks. Molecular dynamics simulations show that SLG suffers a significantly higher compressive stress compared to bilayer graphene when both are under the same compression, thus leading to the rupture of SLG in these fold regions. The fracture strength of a CVD‐grown single‐crystal SLG film is simulated to be about 70 GPa. This study greatly deepens the understanding of the mechanics of CVD‐grown single‐crystal graphene and such folds, and sheds light on the fabrication of various graphene origami/kirigami structures by substrate engineering. Such oriented folds can be used in a variety of further studies.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Folding and Fracture of Single‐Crystal Graphene Grown on a Cu(111) Foil

et al. 2022

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“…By accurately controlling the deposition temperature, fold-free largearea single-crystal graphene films have been fabricated on Cu-Ni alloyed foils. [289] Efforts to directly grow 2D films onto integrated substrates, such as silicon and silica, [305,307] have further advanced CVD techniques. In addition, by evaporating different dopants during the CVD growth process, in-situ substitutional doping of both cations and anions has also been achieved.…”

Section: Chemical Vapor Depositionmentioning

confidence: 99%

Fabrication Technologies for the On‐Chip Integration of 2D Materials

Jia

Zhang

et al. 2022

Small Methods

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The carrier mobilities of all the listed materials are experimental results except for those of SnSe, MoO 3 , MoSSe, WSSe, and graphdiyne that are theoretical calculated values; b) The n, k values for all the listed materials are at 1550 nm except for BP at 800 nm and h-BN at 1200 nm; c) The NLO parameters of PdSe 2 , PtSe 2 , BP, h-BN, MoO 3 , and CsPbBr 3 are at 800 nm. Those of MoS 2 and Bi 2 Te 3 are at 1060 nm. Those of other materials are at 1550 nm. In addition to third-order optical nonlinearity, strong second-order optical nonlinearity has been observed for graphene, GO, MoS 2 , WSe 2 , PdSe 2 , and h-BN, with typical χ (2) values varying from 10 -12 -10 -7 m V -1 . [33,[116][117][118][119][120] ; d) The values of n 2 and β are dependent on the film thickness, here we only provide typical values obtained from experimental measurements.

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“…It should be noted that at large lateral scales of order 1 cm, graphene is expected to have wrinkles and folds, which were observed in our SEM-EDX analysis (Fig. 1c and Fig S6 ), resulting from its chemical vapor deposition (CVD) growth on the initial Cu substrate [28] and its transfer. Hexagonal domains, also visible on these SEM images (Fig.…”

mentioning

confidence: 78%

Alumina Graphene Catalytic Condenser for Programmable Solid Acids

Onn

Gathmann

Wang

et al. 2022

Preprint

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Precise control of electron density at catalyst active sites enables regulation of surface chemistry for optimal rate and selectivity to products. Here, an ultrathin catalytic film of amorphous alumina (4 nm) was integrated into a catalytic condenser device that enabled tunable electron depletion from the alumina active layer and correspondingly stronger Lewis acidity. The catalytic condenser had the following structure: amorphous alumina/graphene/HfO2 dielectric (70 nm)/p-type Si. Application of positive voltages up to +3 V between graphene and the p-type Si resulted in electrons flowing out of the alumina; positive charge accumulated in the catalyst. Temperature programmed surface reaction of thermocatalytic isopropanol dehydration to propene on the charged alumina surface revealed a shift in the propene formation peak temperature of up to ΔT(peak)~50 ⁰C relative to the uncharged film, consistent with a 16 kJ/mol (0.17 eV) reduction in the apparent activation energy. Electrical characterization of the thin amorphous alumina film by ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling microscopy (STM) indicates the film is a defective semiconductor with an appreciable density of in-gap electronic states. Density functional theory calculations of isopropanol binding on the pentacoordinate aluminum active sites indicate significant binding energy changes (ΔBE) up to 60 kJ/mol (0.62 eV) for 0.125 e- depletion per active site, supporting the experimental findings. Overall, the results indicate that continuous and fast electronic control of thermocatalysis can be achieved with the catalytic condenser device.

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Single-crystal, large-area, fold-free monolayer graphene

Cited by 268 publications

References 35 publications

Folding and Fracture of Single‐Crystal Graphene Grown on a Cu(111) Foil

Folding and Fracture of Single‐Crystal Graphene Grown on a Cu(111) Foil

Fabrication Technologies for the On‐Chip Integration of 2D Materials

Alumina Graphene Catalytic Condenser for Programmable Solid Acids

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