Graphene Liquid Cell Research Articles

Direct Realization of Complete Conversion and Agglomeration Dynamics of SnO2 Nanoparticles in Liquid Electrolyte.

The conversion reaction is important in lithium-ion batteries because it governs the overall battery performance, such as initial Coulombic efficiency, capacity retention, and rate capability. Here, we have demonstrated in situ observation of the complete conversion reaction and agglomeration of nanoparticles (NPs) upon lithiation by using graphene liquid cell transmission electron microscopy. The observation reveals that the Sn NPs are nucleated from the surface of SnO2, followed by merging with each other. We demonstrate that the agglomeration has a stepwise process, including rotation of a NP, formation of necks, and subsequent merging of individual NPs.

Dynamic Nanobubbles in Graphene Liquid Cell under Electron Beam Irradiation

Dynamic Nanobubbles in Graphene Liquid Cell under Electron Beam Irradiation

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

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.

Bio-camouflage of anatase nanoparticles explored by in situ high-resolution electron microscopy.

While titanium is the metal of choice for most prosthetics and inner body devices due to its superior biocompatibility, the discovery of Ti-containing species in the adjacent tissue as a result of wear and corrosion has been associated with autoimmune diseases and premature implant failures. Here, we utilize the in situ liquid cell transmission electron microscopy (TEM) in a liquid flow holder and graphene liquid cells (GLCs) to investigate, for the first time, the in situ nano-bio interactions between titanium dioxide nanoparticles and biological medium. This imaging and spectroscopy methodology showed the process of formation of an ionic and proteic bio-camouflage surrounding Ti dioxide (anatase) nanoparticles that facilitates their internalization by bone cells. The in situ understanding of the mechanisms of the formation of the bio-camouflage of anatase nanoparticles may contribute to the definition of strategies aimed at the manipulation of these NPs for bone regenerative purposes.

The Use of Graphene and Its Derivatives for Liquid-Phase Transmission Electron Microscopy of Radiation-Sensitive Specimens.

One of the key challenges facing liquid-phase transmission electron microscopy (TEM) of biological specimens has been the damaging effects of electron beam irradiation. The strongly ionizing electron beam is known to induce radiolysis of surrounding water molecules, leading to the formation of reactive radical species. In this study, we employ DNA-assembled Au nanoparticle superlattices (DNA-AuNP superlattices) as a model system to demonstrate that graphene and its derivatives can be used to mitigate electron beam-induced damage. We can image DNA-AuNP superlattices in their native saline environment when the liquid cell window material is graphene, but not when it is silicon nitride. In the latter case, initial dissociation of assembled AuNPs was followed by their random aggregation and etching. Using graphene-coated silicon nitride windows, we were able to replicate the observation of stable DNA-AuNP superlattices achieved with graphene liquid cells. We then carried out a correlative Raman spectroscopy and TEM study to compare the effect of electron beam irradiation on graphene with and without the presence of water and found that graphene reacts with the products of water radiolysis. We attribute the protective effect of graphene to its ability to efficiently scavenge reactive radical species, especially the hydroxyl radicals which are known to cause DNA strand breaks. We confirmed this by showing that stable DNA-AuNP assemblies can be imaged in silicon nitride liquid cells when graphene oxide and graphene quantum dots, which have also recently been reported as efficient radical scavengers, are added directly to the solution. We anticipate that our study will open up more opportunities for studying biological specimens using liquid-phase TEM with the use of graphene and its derivatives as biocompatible radical scavengers to alleviate the effects of radiation damage.

Distortion in Two-Dimensional Shapes of Merging Nanobubbles: Evidence for Anisotropic Gas Flow Mechanism.

Two nanobubbles that merge in a graphene liquid cell take elliptical shapes rather than the ideal circular shapes. This phenomenon was investigated in detail by using in situ transmission electron microscopy (TEM). The results show that the distortion in the two-dimensional shapes of the merging nanobubbles is attributed to the anisotropic gas transport flux between the nanobubbles. We also predicted and confirmed the same phenomenon in a three-nanobubble system, indicating that the relative size difference is important in determining the shape of merging nanobubbles.

Graphene‐sealed Si/SiN cavities for high‐resolution in situ electron microscopy of nano‐confined solutions

We demonstrate new liquid cell architectures utilizing graphene‐sealed Si or SiN cavities for in situ electron microscopy. While previous graphene liquid cell techniques have shown graphene to be an ideal sealing layer and electron‐transparent viewing window, they trap irregular geometries of liquid with unknown sample volumes. Our new technique allows for a leak‐proof confinement of liquids of precise volume in the tens of attoliter range while maintaining the benefits of graphene as a viewing window. The utility of this new cell architecture is demonstrated by imaging the dynamics of gold nanoparticles in three dimensions with atomic resolution under a transmission electron microscope.

Precise In Situ Modulation of Local Liquid Chemistry via Electron Irradiation in Nanoreactors Based on Graphene Liquid Cells.

A controlled electron-water radiolysis process is used to generate predictable concentrations of radical and ionic species in graphene liquid cells, allowing the concept of a nanoscale chemical reactor. A differential scanning technique is used to generate the desired time- and space-varying electron dose rate. Precise control of the local concentration of H2 , the dominant radiolysis species, is demonstrated experimentally at the nanometer scale.

Structural Integrity of SnO 2 Nanotubes During Sodiation Examined by in Situ TEM Observation with Graphene Liquid Cell

Structural Integrity of SnO 2 Nanotubes During Sodiation Examined by in Situ TEM Observation with Graphene Liquid Cell

Case Examination on Volume Expansion of Crystalline Si Nanoparticles under Sodiation: In Situ TEM Study Using Graphene Liquid Cells

Case Examination on Volume Expansion of Crystalline Si Nanoparticles under Sodiation: In Situ TEM Study Using Graphene Liquid Cells

Elucidation of Structure and Chemistry of Iron Core in Human Heart Ferritin via Graphene Liquid Cell

Elucidation of Structure and Chemistry of Iron Core in Human Heart Ferritin via Graphene Liquid Cell

In Situ TEM Observation on the Growth and Agglomeration of Propylene Carbonate-based Electrolytes During Sodiation with Graphene Liquid Cell

In Situ TEM Observation on the Growth and Agglomeration of Propylene Carbonate-based Electrolytes During Sodiation with Graphene Liquid Cell

Spatially Resolved Electron Energy Loss Spectroscopy Studies in Graphene Liquid Cell for the Investigation of the Biomineralization Processes in Human Body

Spatially Resolved Electron Energy Loss Spectroscopy Studies in Graphene Liquid Cell for the Investigation of the Biomineralization Processes in Human Body

Growth dynamics of solid electrolyte interphase layer on SnO2 nanotubes realized by graphene liquid cell electron microscopy

Formation of stable solid electrolyte interphase (SEI) layer is critical to outstanding performance of energy storage devices, because it acts as a passive layer that allows facile transport of ions but forbids electron transport between the electrolyte and electrode. Although much study has been devoted to investigate the morphology and structure of SEI layer using a myriad of analytical devices on past decades, the direct observation of SEI layer on a real time scale has remained as a formidable challenge. In addition, it has been difficult to observe both the decomposition of electrolytes and formation process of stable SEI layer at nanometer scale. Here we utilize in situ transmission electron microscopy (TEM) using graphene liquid cell (GLC) to realize the observation of stable SEI layer formation in a sequential time scale. Upon e− beam irradiation, Li salts in the electrolytes react with reduced electrolytes and form gel-like agglomerates, which are deposited on the surface of the active material as a passivation layer and later stabilized to become more uniform in overall thickness. Additionally, growth dynamics of stable SEI layer were suggested, where the deposition of decomposed electrolytes eventually result in relatively uniform SEI layer. This paper demonstrates that it is possible to observe not only the formation of non-crystalline SEI layer but also the movement of decomposed electrolytes onto the surface of active materials which account for broader understanding of SEI layer, and has the potential to detect important interfacial phenomena in electrochemical devices that were overlooked so far.

Efficient preparation of graphene liquid cell utilizing direct transfer with large-area well-stitched graphene

By utilizing graphene-sandwiched structures recently developed in this laboratory, we are able to visualize small droplets of liquids in nanometer scale. We have found that small water droplets as small as several tens of nanometers sandwiched by two single-layer graphene are frequently observed by TEM. Due to the electron beam irradiation during the TEM observation, these sandwiched droplets are frequently moving from one place to another and are subjected to create small bubbles inside. The synthesis of a large area single-domain graphene of high-quality is essential to prepare the graphene sandwiched cell which safely encapsulates the droplets in nanometer size.

Real-Time Observation of Water-Soluble Mineral Precipitation in Aqueous Solution by In Situ High-Resolution Electron Microscopy.

The precipitation and dissolution of water-soluble minerals in aqueous systems is a familiar process occurring commonly in nature. Understanding mineral nucleation and growth during its precipitation is highly desirable, but past in situ techniques have suffered from limited spatial and temporal resolution. Here, by using in situ graphene liquid cell electron microscopy, mineral nucleation and growth processes are demonstrated in high spatial and temporal resolution. We precipitate the mineral thenardite (Na2SO4) from aqueous solution with electron-beam-induced radiolysis of water. We demonstrate that minerals nucleate with a two-dimensional island structure on the graphene surfaces. We further reveal that mineral grains grow by grain boundary migration and grain rotation. Our findings provide a direct observation of the dynamics of crystal growth from ionic solutions.

Graphene-Based Platform for Infrared Near-Field Nanospectroscopy of Water and Biological Materials in an Aqueous Environment.

Scattering scanning near-field optical microscopy (s-SNOM) has emerged as a powerful nanoscale spectroscopic tool capable of characterizing individual biomacromolecules and molecular materials. However, applications of scattering-based near-field techniques in the infrared (IR) to native biosystems still await a solution of how to implement the required aqueous environment. In this work, we demonstrate an IR-compatible liquid cell architecture that enables near-field imaging and nanospectroscopy by taking advantage of the unique properties of graphene. Large-area graphene acts as an impermeable monolayer barrier that allows for nano-IR inspection of underlying molecular materials in liquid. Here, we use s-SNOM to investigate the tobacco mosaic virus (TMV) in water underneath graphene. We resolve individual virus particles and register the amide I and II bands of TMV at ca. 1520 and 1660 cm(-1), respectively, using nanoscale Fourier transform infrared spectroscopy (nano-FTIR). We verify the presence of water in the graphene liquid cell by identifying a spectral feature associated with water absorption at 1610 cm(-1).

Using Graphene Liquid Cells for High-resolution Chemical Analysis of Nano-particle Reactions

Using Graphene Liquid Cells for High-resolution Chemical Analysis of Nano-particle Reactions

Direct Observation of Wet Biological Samples by Graphene Liquid Cell Transmission Electron Microscopy.

Recent development of liquid phase transmission electron microscopy (TEM) enables the study of specimens in wet ambient conditions within a liquid cell; however, direct structural observation of biological samples in their native solution using TEM is challenging since low-mass biomaterials embedded in a thick liquid layer of the host cell demonstrate low contrast. Furthermore, the integrity of delicate wet samples is easily compromised during typical sample preparation and TEM imaging. To overcome these limitations, we introduce a graphene liquid cell (GLC) using multilayer graphene sheets to reliably encapsulate and preserve biological samples in a liquid for TEM observation. We achieve nanometer scale spatial resolution with high contrast using low-dose TEM at room temperature, and we use the GLC to directly observe the structure of influenza viruses in their native buffer solution at room temperature. The GLC is further extended to investigate whole cells in wet conditions using TEM. We also demonstrate the potential of the GLC for correlative studies by TEM and fluorescence light microscopy imaging.

Growth dynamics and gas transport mechanism of nanobubbles in graphene liquid cells.

Formation, evolution and vanishing of bubbles are common phenomena in nature, which can be easily observed in boiling or falling water, carbonated drinks, gas-forming electrochemical reactions and so on. However, the morphology and the growth dynamics of the bubbles at nanoscale have not been fully investigated owing to the lack of proper imaging tools that can visualize nanoscale objects in the liquid phase. Here, we demonstrate for the first time that the nanobubbles in water encapsulated by graphene membrane can be visualized by in-situ ultra-high vacuum transmission electron microscopy. Our microscopic results indicate two distinct growth mechanisms of merging nanobubbles and the existence of a critical radius of nanobubbles that determines the unusually long stability of nanobubbles. Interestingly, the gas transport through ultrathin water membranes at nanobubble interface is free from dissolution, which is clearly different from conventional gas transport that includes condensation, transmission and evaporation.