layeredmaterial

Layered material refers to a solid composed of two-dimensional sheets stacked atop one another, bound together by relatively weak interlayer forces, usually van der Waals interactions. Within each layer, atoms are held by strong in-plane bonds, while the weak interlayer coupling allows easy separation into thin sheets. This structural motif enables exfoliation to produce atomically thin layers with high surface area and properties that differ markedly from the bulk.

Common families include graphite and other layered carbons, transition metal dichalcogenides (such as MoS2, WS2, MoSe2, WSe2), hexagonal boron nitride, and black phosphorus (phosphorene). These materials can be metallic, semiconducting, or insulating, and their electronic and optical characteristics often depend on the number of layers.

Properties of layered materials are highly anisotropic, with in-plane and out-of-plane behaviors differing. Thickness and stacking influence band gaps, carrier mobility, and catalytic activity. Interlayer spacing can be adjusted through chemical intercalation or strain, enabling tunable properties.

Fabrication and processing methods include mechanical exfoliation (peeling layers from bulk crystals), liquid-phase exfoliation, chemical intercalation, and chemical vapor deposition or epitaxial growth to form thin films. Characterization typically uses atomic force microscopy to measure thickness, transmission electron microscopy for structure, and Raman spectroscopy to assess layer number and quality.

Applications span electronics and optoelectronics (transistors, sensors, photodetectors), energy storage and catalysis (electrocatalysis and battery electrodes), and reinforcing components in composites. Challenges include scalable production with controlled layer number, defect management, environmental stability for some materials, and integration into existing manufacturing pipelines. The discovery of graphene in 2004 by Geim and Novoselov popularized the broader class of layered materials, earning the 2010 Nobel Prize in Physics.