Nonequilibrium Flow-Synthesis of Solid-Solution Alloy Nanoparticles: From Immiscible Binary to High-Entropy Alloys

Solid-solution alloy nanoparticles (NPs), where the constituents mix at the atomic level, show a variety of attractive properties due to their tunable electronic structures. However, it is still difficult to stably synthesize them, particularly nonequilibrium alloys that consist of combinations immiscible in the bulk. Here, we first report the successful syntheses of solid-solution alloy NPs including PdRu and PdRuIr, which are immiscible in the bulk, and of IrPdPtRhRu high-entropy alloy NPs through a continuous-flow reactor providing a high productivity with high reproducibility. The designed solvothermal flow reactor enabled us to use a lower alcohol as a reductant that cannot be applied in a batch synthesis for these NPs.