Method for Synthesizing High-Entropy Alloy (HEA) Nanostructures

Abstract

A method for synthesizing high-entropy alloy (HEA) nanostructures, each having a HEA shell uniformly grown on a nanocore, is provided. The method comprises: mixing nanostructure seeds, a plurality of metal precursors, one or more reducing agents and a surfactant in a solvent to form a first mixture; subjecting the first mixture to ultrasonication under an ultrasonication temperature; degassing the first mixture upon heating at a degassing temperature under vacuum with magnetic stirring; purging the first mixture with an inert gas; and keeping the first mixture at a growth temperature for a growth time to form the HEA nanostructures. The provided method is a low-temperature, facile, general, wet-chemical, seeded epitaxial growth method which can synthesize a library of unconventional-phase HEA nanostructures, e.g., 4H-Au@HEA nanowires and 2H/fcc-Au@HEA nanosheets with 5-10 components by using 4H-Au NWs and 2H/fcc-Au NSs as seeds respectively.

What is claimed is: 
     
         1 . A method for synthesizing high-entropy alloy (HEA) nanostructures, each having a HEA shell uniformly grown on a nanocore, the method comprising:
 mixing nanostructure seeds, a plurality of metal precursors, one or more reducing agents and a surfactant in a solvent to form a first mixture;   subjecting the first mixture to ultrasonication under an ultrasonication temperature;   degassing the first mixture upon heating at a degassing temperature under vacuum with magnetic stirring;   purging the first mixture with an inert gas; and   keeping the first mixture at a growth temperature for a growth time to form the HEA nanostructures.   
     
     
         2 . The method of  claim 1 , wherein the nanostructure seeds are 4H—Au nanowire seeds such that the nanocore is a nanowire formed of 4H—Au. 
     
     
         3 . The method of  claim 2 , wherein the plurality of metal precursors includes Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound, and Fe-based compound such that the HEA shell is formed of quinary 4H—IrPtNiCoFe. 
     
     
         4 . The method of  claim 3 , wherein the Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound and Fe-based compound are Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3  and Fe(acac) 3 , respectively. 
     
     
         5 . The method of  claim 4 , wherein the 4H—Au nanowire seeds, the metal precursors Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3 , and Fe(acac) 3  have weight ratio of 5:5:2:3:3. 
     
     
         6 . The method of  claim 1 , wherein the nanostructure seeds are 2H/fcc-Au nanosheet seeds such that the nanocore is a nanosheet formed of 2H/fcc-Au. 
     
     
         7 . The method of  claim 6 , wherein the plurality of metal precursors includes Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound, and Fe-based compound such that the HEA shell is formed of quinary 2H/fcc-IrPtNiCoFe. 
     
     
         8 . The method of  claim 7 , wherein the Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound and Fe-based compound are Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3  and Fe(acac) 3 , respectively. 
     
     
         9 . The method of  claim 8 , wherein the 4H—Au nanowire seeds, the metal precursors Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3 , and Fe(acac) 3  have weight ratio of 5:5:2:3:3. 
     
     
         10 . A high-entropy alloy (HEA) nanostructure having a HEA shell uniformly grown on a nanocore, wherein the HEA nanostructure is synthesized by the method of  claim 1 . 
     
     
         11 . The high-entropy alloy (HEA) nanostructure of  claim 10 , wherein the nanostructure seeds are 4H—Au nanowire seeds such that the nanocore is a nanowire formed of 4H—Au. 
     
     
         12 . The high-entropy alloy (HEA) nanostructure of  claim 11 , wherein the plurality of metal precursors includes Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound, and Fe-based compound such that the HEA shell is formed of quinary 4H—IrPtNiCoFe. 
     
     
         13 . The high-entropy alloy (HEA) nanostructure of  claim 12 , wherein the Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound and Fe-based compound are Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3  and Fe(acac) 3 , respectively. 
     
     
         14 . The high-entropy alloy (HEA) nanostructure of  claim 13 , wherein the 4H—Au nanowire seeds, the metal precursors Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3 , and Fe(acac) 3  have weight ratio of 5:5:2:3:3. 
     
     
         15 . The high-entropy alloy (HEA) nanostructure of  claim 14 , wherein the nanostructure seeds are 2H/fcc-Au nanosheet seeds such that the nanocore is a nanosheet formed of 2H/fcc-Au. 
     
     
         16 . The high-entropy alloy (HEA) nanostructure of  claim 15 , wherein the plurality of metal precursors includes Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound, and Fe-based compound such that the HEA shell is formed of quinary 2H/fcc-IrPtNiCoFe. 
     
     
         17 . The high-entropy alloy (HEA) nanostructure of  claim 16 , wherein the Pt-based compound, Ir-based compound, Ni-based compound, Co-based compound and Fe-based compound are Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3  and Fe(acac) 3 , respectively. 
     
     
         18 . The high-entropy alloy (HEA) nanostructure of  claim 17 , wherein the 4H—Au nanowire seeds, the metal precursors Pt(acac) 2 , Ir(acac) 3 , Ni(acac) 2 , Co(acac) 3 , and Fe(acac) 3  have weight ratio of 5:5:2:3:3. 
     
     
         19 . A bifunctional catalyst comprising the high-entropy alloy (HEA) nanostructures of  claim 10 . 
     
     
         20 . A proton exchange membrane-based electrolyzer, comprising an anode and a cathode, both applied with bifunctional catalyst of  claim 19 .