A Universal Atomic Substitution Conversion Strategy Towards Synthesis of Large-Size Ultrathin Nonlayered Two-Dimensional Materials

Abstract

Nonlayered two-dimensional (2D) materials have attracted increasing attention, due to novel physical properties, unique surface structure, and high compatibility with microfabrication technique. However, owing to the inherent strong covalent bonds, the direct synthesis of 2D planar structure from nonlayered materials, especially for the realization of large-size ultrathin 2D nonlayered materials, is still a huge challenge. Here, a general atomic substitution conversion strategy is proposed to synthesize large-size, ultrathin nonlayered 2D materials. Taking nonlayered CdS as a typical example, large-size ultrathin nonlayered CdS single-crystalline flakes are successfully achieved via a facile low-temperature chemical sulfurization method, where pre-grown layered CdI2 flakes are employed as the precursor via a simple hot plate assisted vertical vapor deposition method. The size and thickness of CdS flakes can be controlled by the CdI2 precursor. The growth mechanism is ascribed to the chemical substitution reaction from I to S atoms between CdI2 and CdS, which has been evidenced by experiments and theoretical calculations. The atomic substitution conversion strategy demonstrates that the existing 2D layered materials can serve as the precursor for difficult-to-synthesize nonlayered 2D materials, providing a bridge between layered and nonlayered materials, meanwhile realizing the fabrication of large-size ultrathin nonlayered 2D materials.

Preparation of 2D Molybdenum Phosphide via Surface‐Confined Atomic Substitution

“…[ 2 ] Unlike layered 2D materials (L2DMs), where each crystalline layer is held together by weak van der Waals interactions, NL2DMs are formed by strong covalent bonds in all three dimensions. [ 3 ] Owing to the multibody interactions, NL2DMs have demonstrated amazing physical properties in electronic transport, [ 4 ] thermal conductance, [ 5 ] heat capacity [ 6 ] as well as quasi‐particle dynamics, [ 7 ] showing great performance in electronics, [ 8 ] optoelectronics, [ 9 ] and energy storage. [ 10 ] Moreover, besides the clear benefit of a large exposed surface, the introduction of 2D morphology to nonlayered materials could also bring large structural distortion and low‐coordinated surface atoms with abundant dangling bonds, which are particularly favored in various catalytic applications.…”

Defect-State Transition Associated Hole Dynamics in Cuprous Iodide Nanosheets

“…The crystalline γ-CuI nanosheets with a sharp edge and smooth surface, as shown in Figure a, were synthesized on mica substrates by a hot-plate-assisted vertical vapor deposition method. , The synthesis yielded nanosheets with size mostly of couple tens of micrometers, which are much larger than those grown by conventional vertical vapor phase deposition method, and with thickness spanning from a few to couple hundred nanometers. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses show that our samples are high quality single crystals with cubic crystal structure grown along the [111] direction, see Figure b.…”

Intelligent Optoelectronic Devices for Next‐Generation Artificial Machine Vision

“…Specifically, a novel atomic substitution transformation strategy is proposed by Zhai in 2021, which promotes the anisotropic growth of metal sulfide. [ 77 ] In this work, the layered CdI 2 nanosheets were used as the precursor template and subjected to the low‐temperature gas‐phase sulfurization technology to prepare single‐crystalline CdS nanofilm with sub‐millimeter size and atomic layer thickness. Converting layered materials into high‐quality, large‐scale nonlayered materials provides a new approach for scientists to prepare metal compound thin films with expected morphologies.…”