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Octahedral molecular sieves (OMSs) based on MnO

As an emerging ultrathin semiconductor material, Bi2O2Se exhibits prominent performances in electronics, optoelectronics, ultrafast optics, etc. However, until now, the in-plane growth of Bi2O2Se thin films is mostly fulfilled on atomically flat mica substrates with interfacial electrostatic forces setting obstacles for Bi2O2Se transfer to fabricate functional van der Waals heterostructures. In this work, controlled growth of inclined Bi2O2Se ultrathin films is realized with apparently reduced interfacial contact areas upon mica flakes. Consequently, the transfer of Bi2O2Se could be facile by overcoming weaker electrostatic interactions. From cross-sectional characterizations at the Bi2O2Se/mica interfaces, it is found that there are no oxide buffer layers in existence for both in-plane and inclined growths, while the un-neutralized charge density is apparently decreased for inclined films. By mechanical pressing, inclined Bi2O2Se could be transferred onto SiO2/Si substrates, and back-gated Bi2O2Se field effect transistors are fabricated, outperforming previously reported in-plane Bi2O2Se devices transferred with the assistance of corrosive acids and adhesive polymers. Furthermore, Bi2O2Se/graphene heterostructures are fulfilled by a probe tip to fabricate hybrid phototransistors with pristine interfaces, exhibiting highly efficient photoresponses. The results in this work demonstrate the potential of inclined Bi2O2Se to act as a building block for prospective van der Waals heterostructures.

A molecule-confined two-dimensional (2D) hybrid superlattice is emerging for uncovering the chemical properties as well as distinctive physical phenomenon arising from the interface electronic stat...

Since the discovery of graphene, van der Waals (vdW) two-dimensional (2D) materials have attracted considerable attention for various potential applications. Recently, a Se-terminated bismuth oxychalcogenide, Bi2O2Se, has been fabricated using the vapor deposition method. Bi2O2Se is not a vdW 2D material, but the as-grown substance shows 2D characteristics. For example, Bi2O2Se exhibits layer number-dependent absorption spectra in experiments, but until now, there has been no reasonable explanation as to why. Here, we propose a 50% Se-passivation surface model, which elucidates the production of such spectra. Our model is also consistent with recent observations using scanning tunneling microscopy. Moreover, high-resolution transmission electron microcopy observations show a broken zipper-like structure in Bi2O2Se. We ascribe Bi2O2Se as a zipper 2D material, and we summarize the characteristics of zipper 2D materials while proposing the development of others. Zipper 2D materials not only are an important subset of 2D materials but also bridge the gap between vdW 2D materials and traditional 3D materials. Because they are a big family, including insulators, semiconductors, and magnetic metals, zipper 2D materials lend themselves to a plethora of applications.

Phase transformation in emerging two-dimensional (2D) materials is crucial for understanding and controlling the interplay between structure and electronic properties. In this work, we investigate ...

As an emerging ultrathin semiconductor material, Bi

A molecule-confined two-dimensional (2D) hybrid superlattice is emerging for uncovering the chemical properties as well as distinctive physical phenomenon arising from the interface electronic states. An efficient and convenient synthetic method represents an important precondition to implementing the superlattice in terminal applications and functional devices. Herein, we develop an approach of spontaneous molecular intercalation to obtain a TaS

Since the discovery of graphene, van der Waals (vdW) two-dimensional (2D) materials have attracted considerable attention for various potential applications. Recently, a Se-terminated bismuth oxychalcogenide, Bi

Phase transformation in emerging two-dimensional (2D) materials is crucial for understanding and controlling the interplay between structure and electronic properties. In this work, we investigate 2D In

Phase transitions and phase engineering in two-dimensional MoS2 are important for applications in electronics and energy storage. By in situ transmission electron microscopy, we find that H-MoS2 transforms to T-LiMoS2 at the early stages of lithiation followed by the formation of Mo and Li2S phases. The transition from H-MoS2 to T-LiMoS2 is explained in terms of electron doping and electron-phonon coupling at the conduction band minima. Both are essential for the development of two-dimensional semiconductor-metal contacts based on MoS2 and the usage of MoS2 as anode material in Li ion batteries.

Controlled synthesis of nanomaterials is one of the grand challenges facing materials scientists. In particular, how tunnel-based nanomaterials aggregate during synthesis while maintaining their well-aligned tunneled structure is not fully understood. Here, we describe the atomistic mechanism of oriented attachment (OA) during solution synthesis of tunneled α-MnO2 nanowires based on a combination of in situ liquid cell transmission electron microscopy (TEM), aberration-corrected scanning TEM with subangstrom spatial resolution, and first-principles calculations. It is found that primary tunnels (1 × 1 and 2 × 2) attach along their common {110} lateral surfaces to form interfaces corresponding to 2 × 3 tunnels that facilitate their short-range ordering. The OA growth of α-MnO2 nanowires is driven by the stability gained from elimination of {110} surfaces and saturation of Mn atoms at {110}-edges. During this process, extra [MnOx] radicals in solution link the two adjacent {110} surfaces and bond with the unsaturated Mn atoms from both surface edges to produce stable nanowire interfaces. Our results provide insights into the controlled synthesis and design of nanomaterials in which tunneled structures can be tailored for use in catalysis, ion exchange, and energy storage applications.

In the present work, taking advantage of aberration-corrected scanning transmission electron microscopy, we show that the dynamic lithiation process of anode materials can be revealed in an unprecedented resolution. Atomically resolved imaging of the lithiation process in SnO2 nanowires illustrated that the movement, reaction, and generation of b = [1[overline]1[overline]1] mixed dislocations leading the lithiated stripes effectively facilitated lithium-ion insertion into the crystalline interior. The geometric phase analysis and density functional theory simulations indicated that lithium ions initial preference to diffuse along the [001] direction in the {200} planes of SnO2 nanowires introduced the lattice expansion and such dislocation behaviors. At the later stages of lithiation, the Li-induced amorphization of rutile SnO2 and the formation of crystalline Sn and LixSn particles in the Li2O matrix were observed.