In Situ Atomic-Level Studies of Gd Atom Release and Migration on Graphene from a Metallofullerene Precursor

Abstract

We show how Gd based metallofullerene (Gd3N@C80) molecules can be used to create single adatoms and nanoclusters on a graphene surface. An in-situ heating holder within an aberration corrected scanning transmission electron microscope is used to track the adhesion of endohedral metallofullerenes (MFs) to the surface of graphene, followed by Gd metal ejection and diffusion across the surface. Heating to 900 o C is used to promote adatom migration and metal nanocluster formation, enabling direct imaging of the assembly of nanoclusters of Gd. We show that hydrogen can be used to reduce the temperature of MF fragmentation and metal ejection, enabling Gd nanocluster formation on graphene surfaces at temperatures as low as 300 o C. The process of MF fragmentation and metal ejection is captured in-situ and reveals that

Self‐Assembly of Bowlic Supramolecules on Graphene Imaged at the Individual Molecular Level using Heavy Atom Tagging

“…The very bright round particles are impurities from graphene grown on Cu substrate (e.g., Cu, Cr, or Si) that are present on the graphene substrate before molecule deposition. [ 35,39–40 ]…”

“…The very bright round particles are impurities from graphene grown on Cu substrate (e.g., Cu, Cr, or Si) that are present on the graphene substrate before molecule deposition. [35,[39][40] The parallel contrast features observed consist of W-containing calix [4]azoarenes, and these lamellar structures are frequently observed in many areas of high density molecular depositions (Figure 2b,e-h). The power-spectrum of the fast Fourier transform (FFT) from the ADF-STEM image shows the average chain-to-chain spacing to be ≈2.5-2.7 nm (Figure 2c,d).…”

Recent Progress in Using Graphene as an Ultrathin Transparent Support for Transmission Electron Microscopy

“…Metal Clusters: Reproduced with permission. [ 66 ] Copyright 2018, American Chemical Society. Liquid Cells: Reproduced with permission.…”

“…Prior work conducted in this area showed that Gd‐based metallofullerene (Gd 3 N@C 80 ) molecules could be used to create single adatoms and nanoclusters on a graphene surface. [ 66 ] An in situ heating holder within an aberration corrected scanning TEM was used to track the adhesion of EMFs to the surface of graphene, Gd metal ejection, and diffusion across the surface, as shown in Figure 2n–r. The opening of MFs causes cargo release of dopant adatoms on the graphene surface without chemically etching of the underlying graphene or damaging the sample itself, providing an excellent way to create doped graphene monolayers.…”

“…The opening of MFs causes cargo release of dopant adatoms on the graphene surface without chemically etching of the underlying graphene or damaging the sample itself, providing an excellent way to create doped graphene monolayers. [ 66 ] The results showed that the metal ejection dynamics was a result of in situ heating rather than e‐beam‐driven mechanism. TEM proved to be a useful technique in detecting and capturing the dynamics and initial disintegration process as soon as the temperature was increased to 500 o C. In this case, our method can potentially be used for drug delivery and imagine where graphene can act as a host to introduce the Gd atoms.…”