A current article in Nature Communications describes the direct statement of core–shell metallic nanowire progress utilizing superior imaging methods. These strategies allow visualization of atomic-scale processes in colloidal environments, minimizing interference from ligands or natural parts.
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Background
Earlier theoretical fashions of nanocrystal progress sometimes contain classical two-step or multi-stage mechanisms, together with nucleation, monomer addition, and particle fusion. These fashions are sometimes derived from static or ex situ characterizations, which offer restricted details about real-time structural evolution.
Current advances in in situ imaging—significantly liquid-phase transmission electron microscopy (LPTEM)—have allowed researchers to watch nanocrystal formation in resolution at excessive decision.
These research have recognized a wide range of mechanisms, together with heterogeneous and homogeneous nucleation, nanoparticle attachment, and floor processes equivalent to Ostwald ripening.
These components collectively affect nanowire form and measurement. Extra parameters equivalent to floor vitality, interfacial pressure, and steel reactivity additional have an effect on whether or not particles merge into uniform shells or irregular constructions.
Progress orientation, particularly alongside the low-energy 〈111〉 route, has been proven to dominate for noble metals like gold and silver. Nonetheless, the detailed kinetics of steel deposition, the function of mixed-metal techniques, and the influence of experimental circumstances equivalent to temperature and lowering brokers have remained incompletely characterised.
The Present Examine
The researchers used a mixture of low-dose LPTEM, cryogenic transmission electron microscopy (cryo-TEM), and three-dimensional electron tomography to watch nanowire progress in liquid circumstances that simulate colloidal synthesis.
The examine concerned alloy seed nanowires—each chiral and non-chiral—as substrates for depositing metals, together with gold (Au), platinum (Pt), palladium (Pd), iron (Fe), copper (Cu), and nickel (Ni).
Metallic deposition was initiated utilizing chemical precursors and lowering brokers equivalent to sodium borohydride, hydrazine hydrate, and ascorbic acid beneath managed synthesis circumstances. These parameters had been chosen to resemble customary colloidal procedures whereas enabling real-time imaging of progress dynamics.
The imaging centered on distinct progress phases—nucleation, attachment, coalescence, and floor restructuring. Electron tomography supplied three-dimensional reconstructions, whereas methods equivalent to energy-dispersive X-ray spectroscopy (EDS) and scanning transmission electron microscopy (STEM) confirmed composition and construction.
Variations in steel kind, temperature, and lowering agent had been systematically launched to evaluate their results on deposition pathways.
Outcomes and Dialogue
The examine discovered that core–shell nanowire formation usually proceeds via three primary phases. Initially, steel atoms preferentially nucleate on seed nanowires via heterogeneous nucleation, which requires a decrease vitality barrier than nucleation in resolution. This ends in the formation of a skinny, uniform preliminary shell.
Because the response continues, further steel nanoparticles nucleate within the resolution and migrate to the nanowire surfaces. These particles connect in a way influenced by floor vitality concerns and sometimes align alongside crystallographic instructions equivalent to 〈111〉. Following attachment, particles might coalesce, forming both clean shells or extra irregular, knot-like options, relying on steel properties and synthesis circumstances.
Ostwald ripening performed a big function in noble steel techniques (Au, Ag, Pd, Pt), selling the expansion of bigger particles and contributing to floor reconstruction. In distinction, transition metals equivalent to Fe, Ni, Cu, and Ru exhibited lowered ripening results, doubtless resulting from decrease atomic mobility and floor vitality mismatches.
Morphologies ranged from steady, clean coatings to irregular, tough surfaces, formed by the steel species and the processing atmosphere. Noble metals tended to kind extra homogeneous shells, whereas transition metals confirmed slower coalescence and extra different floor options.
Conclusion
This examine supplies detailed perception into the expansion mechanisms of core–shell nanowires beneath colloidal circumstances. By figuring out how steel kind, crystallographic orientation, and response circumstances affect deposition conduct, the analysis contributes to a extra refined understanding of nanowire formation.
These outcomes might inform the design of nanowires with tailor-made floor properties for functions in catalysis, electronics, and vitality storage. The mixing of real-time imaging with managed synthesis provides a framework for additional research geared toward manipulating nanoscale constructions with larger precision.
Journal Reference
Yang D., et al. (2025). Remark of nanoparticle coalescence throughout core-shell metallic nanowire progress in colloids by way of nanoscale imaging. Nature Communications. DOI: 10.1038/s41467-025-60135-3, https://www.nature.com/articles/s41467-025-60135-3
