Atomic Defects in Two‐Dimensional Materials: From Single‐Atom Spectroscopy to Functionalities in Opto‐/Electronics, Nanomagnetism, and Catalysis

Abstract

Two-dimensional layered graphene-like crystals including transition-metal dichalcogenides (TMDs) have received extensive research interest due to their diverse electronic, valleytronic, and chemical properties, with the corresponding optoelectronics and catalysis application being actively explored. However, the recent surge in two-dimensional materials science is accompanied by equally great challenges, such as defect engineering in large-scale sample synthesis. It is necessary to elucidate the effect of structural defects on the electronic properties in order to develop an application-specific strategy for defect engineering. Here, two aspects of the existing knowledge of native defects in two-dimensional crystals are reviewed. One is the point defects emerging in graphene and hexagonal boron nitride, as probed by atomically resolved electron microscopy, and their local electronic properties, as measured by single-atom electron energy-loss spectroscopy. The other will focus on the point defects in TMDs and their influence on the electronic structure, photoluminescence, and electric transport properties. This review of atomic defects in two-dimensional materials will offer a clear picture of the defect physics involved to demonstrate the local modulation of the electronic properties and possible benefits in potential applications in magnetism and catalysis.

Degradation behaviors and mechanisms of MoS2 crystals relevant to bioabsorbable electronics

“…Because of the hexagonal atomic structure of semiconducting MoS 2 in the 2H phase, the misorientation angle ranges from 0°to 60°3 3,36 . The atomic defect structures in MoS 2 grains and GBs greatly affect the mechanical, electrical, and optoelectronic properties of MoS 2 -based devices 35,[37][38][39][40][41][42][43] . To thoroughly explore the degradation behaviors of MoS 2 grains and GBs with different inter-grain misorientation angles, we selected four samples with different angles and characterized their original morphologies and structures.…”

New 2D Carbon Nitride Organic Materials Synthesis with Huge‐Application Prospects in CN Photocatalyst

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2D materials are attracting much more attention because of their unique and outstanding physical and chemical properties. [1][2][3][4][5] A number of their members have also added with the increase in research fields, from graphene to white graphene (h-BN), [6,7] 2D transition metal sulfides, [8,9] black phosphorus nanosheets, and layered metal-organic frameworks. [10][11][12][13][14] However, most of them are inorganic materials, and only few organic 2D materials have been reported.

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Boosting the Electrocatalytic Activity of Co3O4 Nanosheets for a Li-O2 Battery through Modulating Inner Oxygen Vacancy and Exterior Co3+/Co2+ Ratio

“…25 Recently, 2D nanosheets based on transition metal oxides have also attracted great attention as efficient electrocatalysts. [26][27][28][29] In addition, another study also indicates that the surface atoms with lowered coordination number can act as active sites for adsorption of O2. 29 However, the design and large-scale synthesis of noble metal free cathode catalysts with both high ORR and OER reactivity is still a big challenge for the development and application of lithium-air battery.…”