Production of nanostructures

Abstract

Methods of producing nanowires and resulting nanowires are described. In one implementation, a method includes heating a reaction mixture including (i) a solvent; (ii) a metal-containing reagent; (iii) a templating agent; and (iv) a seed-promoting agent (SPA) that is a source of halide anions, thereby producing a product that includes nanowires of the metal. The solvent includes at least two hydroxyl groups per molecule. A ratio of a concentration of the halide anions in the reaction mixture to an overall concentration of the metal in the reaction mixture, including ionic and elemental metal forms, is up to 10. The heating is carried out at a seeding temperature, followed by a growth temperature that is higher than the seeding temperature.

What is claimed is: 
     
         1 . A method of producing nanowires, comprising:
 heating a reaction mixture including
 (i) a solvent; 
 (ii) a metal-containing reagent; 
 (iii) a templating agent; and 
 (iv) a seed-promoting agent (SPA) that is a source of halide anions to produce a product that includes nanowires of the metal, 
   wherein the solvent includes at least two hydroxyl groups per molecule,   wherein a ratio of a concentration of the halide anions in the reaction mixture to an overall concentration of the metal in the reaction mixture, including ionic and elemental metal forms, is up to 10, and   wherein the heating is carried out at a seeding temperature, followed by a growth temperature that is higher than the seeding temperature.   
     
     
         2 . The method of  claim 1 , wherein the solvent includes at least three hydroxyl groups per molecule. 
     
     
         3 . The method of  claim 1 , wherein the solvent has a viscosity higher than 16.9 cP at room temperature. 
     
     
         4 . The method of  claim 1 , wherein the solvent is glycerol. 
     
     
         5 . The method of  claim 1 , wherein the metal is silver, the nanowires are silver nanowires, the metal-containing reagent includes at least one silver-containing salt selected from silver nitrate, silver perchlorate, and silver fluoride, and the templating agent is poly(vinylpyrrolidone). 
     
     
         6 . The method of  claim 1 , wherein the metal is silver, the nanowires are silver nanowires, and the metal-containing reagent is silver perchlorate. 
     
     
         7 . The method of  claim 1 , wherein the overall concentration of the metal in the reaction mixture is less than 0.1 molar. 
     
     
         8 . The method of  claim 7 , further comprising purifying the product to yield a purified product, and wherein at least 30% by number of the nanowires in the purified product have a length of at least 10 μm. 
     
     
         9 . The method of  claim 1 , wherein the metal-containing reagent is in a solution form when combined with other reagents in the reaction mixture. 
     
     
         10 . The method of  claim 1 , wherein the templating agent is in a solid or semi-solid form when combined with other reagents in the reaction mixture. 
     
     
         11 . The method of  claim 1 , wherein the halide anions are chloride anions, and the ratio of the concentration of the chloride anions in the reaction mixture to the overall concentration of the metal in the reaction mixture is in a range of 0.001 to 10. 
     
     
         12 . The method of  claim 1 , wherein the SPA is a first SPA, and the reaction mixture also includes a second SPA that is a source of nitrate anions, and a ratio of a concentration of the nitrate anions in the reaction mixture to the overall concentration of the metal in the reaction mixture is in a range of 0.01 to 10. 
     
     
         13 . A method of producing silver nanowires, comprising:
 heating a reaction mixture including
 (i) a solvent; 
 (ii) a silver-containing reagent; 
 (iii) a templating agent; 
 (iv) a first seed-promoting agent (SPA) that is a source of halide anions; and 
 (v) a second SPA that is a source of nitrate anions to produce silver nanowires, 
   wherein the solvent includes at least three hydroxyl groups per molecule, and   wherein a ratio of a concentration of the nitrate anions in the reaction mixture to an overall concentration of silver in the reaction mixture, including ionic and elemental metal forms, is different from 1.   
     
     
         14 . The method of  claim 13 , wherein the solvent is glycerol. 
     
     
         15 . The method of  claim 13 , wherein the silver-containing reagent also is a source of the nitrate anions in the reaction mixture. 
     
     
         16 . The method of  claim 13 , wherein the silver-containing reagent is silver perchlorate. 
     
     
         17 . The method of  claim 13 , wherein the halide anions are chloride anions, and a ratio of a concentration of the chloride anions in the reaction mixture to the overall concentration of silver in the reaction mixture is in a range of 0.001 to 10. 
     
     
         18 . The method of  claim 13 , wherein the ratio of the concentration of the nitrate anions in the reaction mixture to the overall concentration of silver in the reaction mixture is different from 1 and is in a range of 0.01 to 10. 
     
     
         19 . The method of  claim 13 , wherein the first SPA is a chloride salt, and the second SPA is a nitrate salt. 
     
     
         20 . The method of  claim 13 , wherein the heating is carried out at a seeding temperature, followed by a growth temperature that is higher than the seeding temperature. 
     
     
         21 . A method of producing silver nanowires, comprising:
 in a first stage, heating a first amount of a first silver-containing reagent, a solvent, and a templating agent in a reaction mixture; and   in a second stage subsequent to the first stage, introducing a second amount of a second silver-containing reagent to the reaction mixture,   wherein the second silver-containing reagent is different from silver nitrate.   
     
     
         22 . The method of  claim 21 , wherein the solvent includes at least three hydroxyl groups per molecule. 
     
     
         23 . The method of  claim 21 , wherein the solvent is glycerol. 
     
     
         24 . The method of  claim 21 , wherein the first silver-containing reagent includes at least one silver-containing salt selected from silver nitrate, silver perchlorate, and silver fluoride, and the second silver-containing reagent includes at least one silver-containing salt selected from silver perchlorate and silver fluoride. 
     
     
         25 . The method of  claim 21 , wherein, in the first stage, the templating agent is in a solid or semi-solid form when combined with other reagents in the reaction mixture. 
     
     
         26 . The method of  claim 21 , wherein, in the second stage, the second amount of the second silver-containing reagent is introduced to the reaction mixture, such that an overall concentration of silver in the reaction mixture, including ionic and elemental metal forms, is less than 0.1 molar. 
     
     
         27 . The method of  claim 21 , wherein, in the first stage, the reaction mixture also includes a first seed-promoting agent (SPA) that is a source of halide anions. 
     
     
         28 . The method of  claim 27 , wherein, in the first stage, the reaction mixture also includes a second SPA that is a source of nitrate anions. 
     
     
         29 . The method of  claim 27 , wherein, in the second stage, the second silver-containing reagent is silver perchlorate, the introducing also includes introducing a second SPA to the reaction mixture, and the second SPA is a source of nitrate anions. 
     
     
         30 . The method of  claim 21 , further comprising:
 in a third stage subsequent to the second stage, introducing a third amount of a third silver-containing reagent to the reaction mixture, wherein the third silver-containing reagent is different from silver nitrate.