Synthesis of Honeycomb‐Structured Beryllium Oxide via Graphene Liquid Cells

Abstract

Using high‐resolution transmission electron microscopy and electron energy‐loss spectroscopy, we show that beryllium oxide crystallizes in the planar hexagonal structure in a graphene liquid cell by a wet‐chemistry approach. These liquid cells can feature van‐der‐Waals pressures up to 1 GPa, producing a miniaturized high‐pressure container for the crystallization in solution. The thickness of as‐received crystals is beyond the thermodynamic ultra‐thin limit above which the wurtzite phase is energetically more favorable according to the theoretical prediction. The crystallization of the planar phase is ascribed to the near‐free‐standing condition afforded by the graphene surface. Our calculations show that the energy barrier of the phase transition is responsible for the observed thickness beyond the previously predicted limit. These findings open a new door for exploring aqueous‐solution approaches of more metal‐oxide semiconductors with exotic phase structures and properties in graphene‐encapsulated confined cells.

Epitaxial Growth of Two-Dimensional Insulator Monolayer Honeycomb BeO

“…There have been efforts to synthesize atomically thin BeO on a supporting substrate, , but thus far no convincing evidence of honeycomb structure BeO has been provided until recently. The only experimental evidence of planar h-BeO to date was achieved by a wet chemistry approach in a graphene liquid cell, but the growth was ∼20 layers thick and polycrystalline on the order of tens of nanometers . Nevertheless, these promising theoretical and experimental results strongly suggest that the epitaxial growth of crystalline, monolayer h-BeO is experimentally achievable.…”

“…The only experimental evidence of planar h-BeO to date was achieved by a wet chemistry approach in a graphene liquid cell, but the growth was ∼20 layers thick and polycrystalline on the order of tens of nanometers. 30 Nevertheless, these promising theoretical and experimental results strongly suggest that the epitaxial growth of crystalline, monolayer h-BeO is experimentally achievable.…”

Advances in the Applications of Graphene-Based Nanocomposites in Clean Energy Materials

“…EELS is the inelastic scattering of an incident electron beam in a sample, which is analyzed to obtain the element composition, chemical bond and electronic structure of samples [50]. Wang et al [51] showed that the chemical bond configuration of BeO in a graphene reaction cell had obvious in-plane and inter-plane anisotropy through EELS characterization.…”

“…There are many experimental stations in the synchrotron radiation laboratory, e.g., XPS, SAXRD, XANES, X-ray absorption fine structure (XAFS), X-ray lithography, high spatial resolution X-ray imaging and 3D printing [67,68]. Dispersion FESEM, HRTEM, AFM, SECM [49] Surface properties MC-ICPMS, FTIR, XPS [51] Valence XPS, XANES [65] Orderliness XRPD, HRTEM, Nitrogen adsorption [59] Pore sizes/volumes Nitrogen adsorption [58] Specific surface area Nitrogen adsorption [58]…”

First-principles calculations of the BeO monolayer with chemical functionalization

“…[1][2][3][4][5][6] The first-principles calculations indicated that the BeO monolayer is an indirect semiconductor with a band gap value of 5.34 eV. 5 Regarding experimental efforts, [6][7][8][9][10] Reinelt et al synthesized the BeO monolayer by oxidizing a cleaned Be surface naturally in 2009, 7 and Afanasieva et al synthesized atomically thin BeO on the Mo(112) surface. 6,8 Recently, Zhang et al reported a compelling demonstration of epitaxial BeO monolayer growth on a Ag(111) substrate by molecular beam epitaxy and found that its band gap was about 6 eV according to scanning tunneling spectroscopy.…”