General synthesis of high-entropy alloy and ceramic nanoparticles in nanoseconds

Abstract High-entropy materials (HEMs) including high-entropy alloys (HEAs) and high-entropy ceramics (HECs) at nanoscale have promising prospects in many fields, yet a robust synthesis strategy is lacking. Herein, we present a simple and general approach, laser scanning ablation (LSA), to synthesize a vast library of HEA and HEC nanoparticles (NPs) including alloys, sulfides, oxides, borides, nitrides, phosphides. The LSA method takes only 5 nanoseconds per pulse to ablate the corresponding NPs precursors at atmospheric temperature and pressure in alkanes. The ultra-rapid process ensures up to 9 dissimilar metallic elements combined uniformly regardless of their thermodynamic solubility. As laser pulse precisely confines energy to desired microregions, the LSA method enables HEM NPs loading on various substrates, even thermally-sensitive ones such as metals and glass. Applied as electrocatalysts for overall water splitting, HEM NPs achieved an overpotential of 185 mV @ 10mA cm-2, which was among the best activities. The LSA technique discloses a large collection of new nanostructured HEMs with unique properties and attractive functions. We believe this general strategy will provide a versatile and flexible material platform for a wild range of fields such as biology, catalysis, electronics and magnetics.