Graphical Abstract
Microwave-enabled flash heating/cooling of nanosized metals encapsulated in water-in-oil micelles has beenused to successfully synthesize single-phase nanoparticles of multi-principal element alloys (MPEA). Fourcoinage metals, including Au, Cu, Pd, and Pt, have been chosen to synthesize the ternary and quaternary MPEAnanoparticles, highlighting the promise and generality of this method for the synthesis of single-phase MPEAnanoparticles when the corresponding metal precursors can be simultaneously reduced to metals upon selectiveabsorption of a short microwave pulse.
Abstract
Metal nanoparticles of multi-principal element alloys (MPEA) with a single crystalline phase have been synthesized by flash heating/cooling of nanosized metals encapsulated in micelle vesicles dispersed in an oil phase (e.g., cyclohexane). Flash heating is realized by selective absorption of a microwave pulse in metals to rapidly heat metals into uniform melts. The oil phase barely absorbs microwave and maintains the low temperature, which can rapidly quench the high-temperature metal melts to enable the flash cooling process. The precursor ions of four metals, including Au, Pt, Pd, and Cu, can be simultaneously reduced by hydrazine in the aqueous solution encapsulated in the micelle vesicles. The resulting metals efficiently absorb microwave energy to locally reach a temperature high enough to melt themselves into a uniform mixture. The duration of microwave pulse is crucial to ensure the reduced metals mix uniformly, while the temperature of oil phase is still low to rapidly quench the metals and freeze the single-phase crystalline lattices in alloy nanoparticles. The microwave-enabled flash heating/cooling provides a new method to synthesize single-phase MPEA nanoparticles of many metal combinations when the appropriate water-in-oil micelle systems and the appropriate reduction reactions of metal precursors are available.
京公网安备11010802044758号