Clean Transfer of Large Graphene Single Crystals for High‐Intactness Suspended Membranes and Liquid Cells

Abstract

The atomically thin 2D nature of suspended graphene membranes holds promising in numerous technological applications. In particular, the outstanding transparency to electron beam endows graphene membranes great potential as a candidate for specimen support of transmission electron microscopy (TEM). However, major hurdles remain to be addressed to acquire an ultraclean, high-intactness, and defect-free suspended graphene membrane. Here, a polymer-free clean transfer of sub-centimeter-sized graphene single crystals onto TEM grids to fabricate large-area and high-quality suspended graphene membranes has been achieved. Through the control of interfacial force during the transfer, the intactness of large-area graphene membranes can be as high as 95%, prominently larger than reported values in previous works. Graphene liquid cells are readily prepared by π-π stacking two clean single-crystal graphene TEM grids, in which atomic-scale resolution imaging and temporal evolution of colloid Au nanoparticles are recorded. This facile and scalable production of clean and high-quality suspended graphene membrane is promising toward their wide applications for electron and optical microscopy.

Graphene Liquid Cells Assembled through Loop‐Assisted Transfer Method and Located with Correlated Light‐Electron Microscopy

“…Moreover, the interplay of surface tension between the two water phases (the droplet on the grid and the water underneath the second graphene sheet) causes local water turbulence. For these reasons, the approach yields a highly ruptured and crumbled second graphene layer, even if multilayer or monocrystalline graphene are used . Graphene deposited by the LAT and the touch‐down method onto a paper substrate reveal the difference in surface coverage between both methods (Figure f,g).…”

“…We include here a concise overview of common GLC assembly methods. To our knowledge the most common method comprises the sandwiching of water between two TEM grids carrying graphene on a porous support film . As graphene is supported through the sample assembly procedure, this method has the largest chance of retaining graphene integrity, albeit at the cost of losing graphene flexibility.…”

“…We note that most often, multilayer graphene is used in these methods, because its superior stability. Both multilayer graphene or defect‐free single crystals of graphene has been shown to increase success rates, but the availability of these materials is limited. Moreover, single layer graphene is preferred over multilayer graphene, as the latter is more rigid and often contaminated by the preparation procedure in which single graphene layers are stacked using polymer transfer.…”

Single particle cryo-EM reconstruction of 52 kDa streptavidin at 3.2 Angstrom resolution

“…Examined under the VPP-Cs-corrector-coupled Titan Krios at 300 kV with phase shift ranging from 30 to 120 degrees, the SA specimens demonstrated monodispersed particles with high contrast that could be easily identified and automatically picked ( Figure 1A). We found that the single-crystalline graphene with monolayer of carbon atoms introduced very low background noise to the specimen and could also serve as a good reference for the assessment of the cryo-EM image quality and motion correction with its hexagonal lattice signal 23,24 . After motion correction of the raw movie stacks of the specimen, we calculated the Fourier transform of the motion-corrected micrographs.…”

Structure Design and Composition Engineering of Carbon‐Based Nanomaterials for Lithium Energy Storage

“…Despite the rapid growth of bottom‐up method, industrial level production of graphene is still challenging. Mass production of highly conductive graphene sheets represents an essential step toward the extensive applications of graphene for LBs . Chemical reduction of GO is the most popular technique to prepare graphene with high yields.…”