Facile and green synthesis of monodisperse sub-10 nm copper and tin nanoparticles using <scp>l</scp> -ascorbic acid as the reducing agent

We first optimized a simple and low-cost polyol-based synthesis route for the preparation of stable and monodisperse sub-10 nm copper nanoparticles. Building on this robust approach, we extended the method to tin and succeeded in producing tin nanoparticles that stabilized in an unconventional α-Sn phase, which is remarkable given the metastable character of this phase under ambient conditions. The resulting α-Sn nanoparticles exhibited excellent resistance to oxidation, together with long-term colloidal stability in air, enabling further processing for potential applications. In both cases, inexpensive commercial precursors and mild conditions (80 °C, aqueous or polyol solvents, ascorbic acid as the sole reducing agent, and no inert atmosphere or additional stabilizers) were employed. The nanoparticles were characterized using TEM, UV-visible spectroscopy, ATR-FTIR, ICP-OES, and XPS.