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Abstract Goldbeating is the ancient craft of thinning bulk gold (Au) into gossamer leaves. Pioneered by ancient Egyptian craftsmen, modern mechanized iterations of this technique can fabricate sheets as thin as ∼100 nm. We take inspiration from this millennia-old craft and adapt it to the nanoscale regime, using colloidally synthesized 0D/1D Au nanoparticles (AuNPs) as highly ductile and malleable nanoscopic Au ingots and subjecting them to solid-state, uniaxial compression. The applied stress induces anisotropic morphological transformation of AuNPs into 2D leaf form and elucidates insights into metal nanocrystal deformation at the extreme length scales. The induced 2D morphology is found to be dependent on the precursor 0D/1D NP morphology, size (0D nanosphere diameter and 1D nanorod diameter and length), and their on-substrate arrangement (e.g., interparticle separation and packing order) prior to compression. Overall, this versatile and generalizable solid-state compression technique enables new pathways to synthesize and investigate the anisotropic morphological transformation of arbitrary NPs and their resultant emergent phenomena. 

Abstract Hierarchical heterostructures of two-dimensional (2D) nanomaterials are versatile platforms for nanoscale optoelectronics. Further coupling of these 2D materials with plasmonic nanostructures, especially in non-close-packed morphologies, imparts new metastructural properties such as increased photosensitivity as well as spectral selectivity and range. However, the integration of plasmonic nanoparticles with 2D materials has largely been limited to lithographic patterning and/or undefined deposition of metallic structures. Here we show that colloidally synthesized zero-dimensional (0D) gold nanoparticles of various sizes can be deterministically self-assembled in highly-ordered, anisotropic, non-close-packed, multi-scale morphologies with templates designed from instability-driven, deformed 2D nanomaterials. The anisotropic plasmonic coupling of the particle arrays exhibits emergent polarization-dependent absorbance in the visible to near-IR regions. Additionally, controllable metasurface arrays of nanoparticles by functionalization with varying polymer brushes modulate the plasmonic coupling between polarization dependent and independent assemblies. This self-assembly method shows potential for bottom-up nanomanufacturing of diverse optoelectronic components and can potentially be adapted to a wide array of nanoscale 0D, 1D, and 2D materials. 

Abstract Two-dimensional (2D) materials have recently garnered significant interest due to their novel and emergent properties. A plethora of 2D materials have been discovered and intensively studied, such as graphene, hexagonal boron nitride, transitionmetal dichalcogenides (TMDCs), and other metallic compound MXenes (nitrides, phosphides, and hydroxides), as well as elemental 2D materials (borophene, germanene, phosphorene, silicene, etc.). Considering the widespread interest in conventional van der Waals 2D materials, two-dimensional metallic nanosheets (2DMNS), a recent addition to the 2D materials family, have exhibited diverse potential spanning optics, electronics, magnetics, catalysis, etc. However, the close-packed, non-layered structure and non-directional, isotropic bonding of metallic materials make it difficult to access metals in their 2D forms, unlike 2D van der Waals materials, which have intrinsically layered structure (strong in-plane bonding in addition to the weak interlayer interaction). Until now, conventional top-down and bottom-up synthesis schemes of these 2DMNS have encountered various limitations such as precursor availability, substrate incompatibility, difficulty of control over thickness and stoichiometry, limited thermal budget, etc. To overcome these manufacturing limitations of 2DMNS, here we report a facile, rapid, large-scale, and cost-effective fabrication technique of nanometer-scale copper (Cu) 2DMNS via iterative rolling, folding, and calendering (RFC) that is readily generalizable to other conventional elemental metallic materials. Overall, we successfully show a scalable fabrication technique of 2DMNS. 

Two-dimensional (2D) materials have recently garnered significant interest due to their novel and emergent properties. A plethora of 2D materials have been discovered and intensively studied, such as graphene, hexagonal boron nitride, transition-metal dichalcogenides TMDCs), and other metallic compound MXenes (nitrides, phosphides, and hydroxides), as well as elemental 2D materials (borophene, germanene, phosphorene, silicene, etc.). Considering the widespread interest in conventional van der Waals 2D materials, two-dimensional metallic nanosheets (2DMNS), a recent addition to the 2D materials family, have exhibited diverse potential spanning optics, electronics, magnetics, catalysis, etc. However, the close-packed, non-layered structure and non-directional, isotropic bonding of metallic materials make it difficult to access metals in their 2D forms, unlike 2D van der Waals materials, which have intrinsically layered structure (strong in-plane bonding in addition to the weak interlayer interaction). Until now, conventional top-down and bottom-up synthesis schemes of these 2DMNS have encountered various limitations such as precursor availability, substrate incompatibility, difficulty of control over thickness and stoichiometry, limited thermal budget, etc. To overcome these manufacturing limitations of 2DMNS, here we report a facile, rapid, large-scale, and cost-effective fabrication technique of nanometer-scale copper (Cu) 2DMNS via iterative rolling, folding, and calendering (RFC) that is readily generalizable to other conventional elemental metallic materials. Overall, we successfully show a scalable fabrication technique of 2DMNS.