Copper nanostructures and methods for their preparation

Abstract

Copper nanostructures with relatively small dimensions and method for producing such structures are discloses. The ratios of the various reaction products may be adjusted to produce pentagonal nanowires and other structures such as tadpole shaped nanowires, nanocubes or pentagonal bi-pyramids.

What is claimed is: 
     
         1 . A method of producing a copper nanostructure, the method comprising:
 forming a reaction mixture in a reaction vessel, the reaction mixture comprising a copper-containing compound, a capping agent and a reducing agent; and   reducing the copper-containing compound with the reducing agent to cause copper to form a copper nanostructure, wherein (1) the pressure in the reaction vessel is less than about 190 kPa and/or (2) the temperature of the reaction mixture is less than about 115° C.   
     
     
         2 . The method as set forth in  claim 1  wherein the pressure in the reaction vessel is about atmospheric pressure. 
     
     
         3 . The method as set forth in  claim 1  wherein the capping agent is an alkylamine. 
     
     
         4 . The method as set forth in  claim 3  wherein the alkylamine has less than about 25 carbon atoms. 
     
     
         5 . The method as set forth in  claim 1  wherein the reaction mixture comprises water as a solvent. 
     
     
         6 . The method as set forth in  claim 1  wherein the temperature of the reaction mixture during formation of the nanostructure is less than about 115° C. 
     
     
         7 . The method as set forth in  claim 1  wherein the copper-containing compound is selected from the group consisting of copper (II) sulfate, copper (II) chloride, copper (II) hydroxide and copper (II) nitrate, copper (II) acetate and copper (II) trifluoroacetate. 
     
     
         8 . The method as set forth in  claim 1  wherein the reducing agent is selected from the group consisting of glucose and ascorbic acid. 
     
     
         9 . The method as set forth in  claim 1  wherein the capping agent is selected from the group consisting of hexadecylamine, octadecylamine and oleylamine. 
     
     
         10 . The method as set forth in  claim 1  wherein the capping agent is hexadecylamine. 
     
     
         11 . The method as set forth in  claim 1  wherein the concentration of at least one of the reducing agent and the capping agent in the reaction mixture is controlled to produce a copper nanostructure in the shape of (1) a nanowire, (2) a pentagonal bi-pyramid, (3) a nanowire having a tad-pole shaped portion or (4) a nanocube. 
     
     
         12 . A population of copper nanowire structures, each structure having a length and a diameter, the average diameter of the copper nanowire structures being less than about 40 nm and the average ratio of length to diameter of the copper nanowire structures being at least about 10:1. 
     
     
         13 . The population as set forth in  claim 12  wherein the average ratio of length to diameter of the copper nanowire structures is at least about 50:1. 
     
     
         14 . The population as set forth in  claim 12  wherein the average diameter of the copper nanowire structures is less than about 30 nm. 
     
     
         15 . The population as set forth in  claim 12  wherein the copper nanowire structures comprise at least about 60 wt % copper. 
     
     
         16 . The population as set forth in  claim 12  wherein the population comprises at least about 100 copper nanowires. 
     
     
         17 . A copper nanowire structure, the structure comprising at least about 60 wt % copper and being characterized by a penta-twinned shape. 
     
     
         18 . The copper nanowire structure as set forth in  claim 17  wherein the nanowire structure comprises at least about 60 wt % copper. 
     
     
         19 . The copper nanowire structure as set forth in  claim 17  wherein the ratio of the length to the diameter of the copper nanowire structure is at least about 10:1. 
     
     
         20 . The copper nanowire structure as set forth in  claim 17  wherein the diameter of the structure is less than about 40 nm.