The inevitable molecular stacking of 2D materials with regulated symmetry remains a major challenge. A recent study was published in Journal of Physical Chemistry Letters Addresses this issue by reporting a 2D stack that is twisted by 30° organic Copper nanoclastHe gathers.
Stady: Enhanced chemical stability in twisted dimorphic stacking of two-dimensional copper nanocluster assemblies. Image Credit: Yurchanka Siarhei / Shutterstock.com
Two-dimensional (2D) materials have recently gained prominence due to their superior properties when compared to typical bulk materials. Two-dimensional materials have low weight, high Young’s modulus, high strength, and strong contrast between in-plane and out-of-plane mechanical properties.
Quasi-periodic 2D materials: new research frontiers
The development of quasi-periodic 2D materials has intrigued many researchers in recent years due to their multiple industrial applications. Surprisingly, studies on the production of 2D nanomaterials with quasi-periodic structures remain scarce even after about 40 years.
One explanation for this barrier is that such structures are still difficult to produce using accepted synthetic chemistry concepts. However, recent results show that angular/twisted layers of 2D materials with hexagonal structures may open new possibilities for quasi-periodic crystal arrangement.
For example, twisted, multilayered graphene has been shown to produce quasi-crystalline regularities when layered at a given angle of 30°. Moreover, the identification of superconductivity in magic-angle and multi-layer twisted bilayer graphene increases the possibility of discovering unexpected features in other 2D composites.
The presence of unique physical features in 2D twisted materials was further highlighted by the Raman spectrum in multilayer twisted graphene and photocycles in twisted 2D black phosphorous.
Semi-crystalline for two-dimensional nanostructures
2D nanoparticles are identified as suitable contenders for high-order structural organization with qausicrystallinity. As a result, there is a compelling case for exploring structural organization based on the chemical interaction of 2D materials.
The self-assembly of materials such as colloids, monomers, microemulsions and nanomaterials in the superstructures results in the creation of a quasi-periodic symmetry, which is mainly controlled by entropy. On the other hand, it has also been shown that truncated quaternary quantum dots with directional patching create a tenfold symmetric quasi-crystalline structure.
It is necessary to emphasize that the non-periodic structures that give rise to the superlattice patterns are the result of the random tilt of a discrete matter or single component with the ability to adopt many forms. As a result, establishing a quasi-crystalline organization for a single component, such as 2D nanomaterials of uniform size, remains critical.
Twisted stacking of new 2D copper nanoclusters
Molecular nanoclusters, in particular those of mined metals, are an interesting example of twisted stacking of nanomaterials in superstructures. This is because bonding-mounted metal nanoclusters can crystallize into larger particles based on their interfacial interactions.
In this study, the researchers report that by modifying the interaction mechanism, it is possible to arrange bonding-fixed molecular nanoclusters into two-dimensional nanoparticles with quasi-periodic symmetry.
The researchers collected metal ions and copper molecular groups by reducing the number of metal ions introduced into the reaction medium, resulting in the formation of twisted two-dimensional nanostructures with quasi-periodic symmetry.
A simple synthesis process was used to create copper nanoclusters (CuNCs) reinforced with mercaptobenzoic acid (MBA) and mercaptobenzoic acid (MPA). The as-prepared copper nanoclusters were then complexed with zinc metal ions and shaped into two-dimensional hexagonal nanostructures.
Important study results
The luminescence strength of zinc-modified copper nanoclusters (CuNCs) was significantly increased, indicating a crystalline creation. The 2D copper nanoclusters also showed hexagonal diffraction patterns in the selected region electron diffraction (SAED) pattern study.
This also confirmed the proposed hexagonal lattice for 2D nanomaterials, in which the CuNCs are laid out in a fixed hexagonal pattern.
Transmission electron microscopy indicated the presence of regions of diploid symmetry with apparent loss of transitional symmetry. Photoluminescence tests revealed that stratum aggregation is formed in the liquid medium. In the presence of molecular iodine, the synthesized twisted stacking morphology of the 2D CuNCs outperformed the hexagonal crystals in prolonged photoluminescence and chemical stability.
These findings are expected to pave the way for future research into new chemical and physical properties by designing layered assemblies of luminous or other 2D materials.
Das, P., & Chattopadhyay, A. (2022). Improving chemical stability in twisted dimorphic stacking of two-dimensional copper nanoparticles assemblies. Journal of Physical Chemistry Letters. Available at: https://pubs.acs.org/doi/10.1021/acs.jpclett.2c02300