Ultrafast and surfactant-free synthesis of Sub-3 nm nanoalloys by shear-assisted liquid-metal reduction

The uniform and surfactant-free synthesis of ultrafine alloy nanoparticles (NPs) still remains an ongoing challenge. Here, we developed a general route for synthesizing sub-3 nm nanoalloys on a carbon support via a shear-assisted liquid-metal reduction (SA-LMR) strategy. The utilization of shearing treatment resulted in the rapid release of electrons from the liquid sodium-potassium (NaK) alloy, which enabled the ultrafast reduction of precursor metal ions to metallic nanoalloys at room temperature. As a model system, Pt-Cu NPs with uniform distribution were synthesized and characterized by spectroscopic and microscopic techniques. The size, composition and structure of the Pt-Cu NPs could be tuned by controlling the volume of liquid NaK alloy and the reaction time. To prove the universality and utility of our method, the binary Pt-M (Fe, Co, Ni, and Cu) and ternary Pt-Cu-Fe nanoalloys deposited on a carbon support were prepared as hydrogen evolution reaction (HER) catalysts. This facile, rapid and universal synthesis technique has the potential to be employed in the large-scale production of nanomaterials and suggests a new direction for nanoalloys.