High-entropy alloy nanoparticles synthesized in liquid and atmosphere using femtosecond laser ablation

The incorporation of multiple immiscible elements into colloidal high-entropy alloy (HEA) nanoparticles continues to be a technical challenge, but it possesses manifold technological potential in numerical applications. In this study, we displayed the successful synthesis of high-entropy alloying nanoparticles through femtosecond laser ablation in both liquid and air. Femtosecond laser ablation induces a highly localized thermal effect and thereby generates nanoparticles directly from the bulk with a high fidelity. We display that we can obtain single-phase high-entropy alloying particles from Cu0.2Co0.2Ni0.2Mn0.35Fe0.05 high-entropy alloys, which are synthesized by arc melting and casting. The average particle size is about 50 nm. The size is further controlled by laser parameters. The scalability of the process with a gram level of colloidal HEA nanoparticles per hour is demonstrated. Electrochemical analysis reveals these nanoparticles can work as catalyst for effective oxygen reduction in Al-air batteries.