Synthesis of shape-specific transition metal nanoparticles

Abstract

A method of producing colloidal, shaped nanoparticles of a transition metal or alloys thereof, comprising reducing ions of at least one transition metal in an aqueous solution thereof in the presence of at least one compound, which, at its isoelectric point, is a zwitterion and/or at least one small, non-polymeric anion and the nanoparticles produced thereby.

1 . A method of producing colloidal, shaped nanoparticles of a transition metal or alloys thereof, said method comprising reducing ions of at least one transition metal in an aqueous solution thereof in the presence of at least one compound which, at its isoelectric point, is a zwitterion and/or at least one small, non-polymeric anion.  
   
   
       2 . The method of  claim 1  wherein said transition metal or alloy is Pt or Pt—Ru.  
   
   
       3 . The method of  claim 2  wherein said transition metal ions are Pt ions and are supplied in said aqueous solution by K 2 PtI 6  or H 2 Pt(OH) 6  and said nanoparticles comprise Pt.  
   
   
       4 . The method of  claim 3  wherein said transition metal ions also include Ru ions, supplied in said aqueous solution by RuI 3 , Ru(NO)(OAc) 3  or Ru(CO) 12  and said nanoparticles comprise a Pt—Ru alloy.  
   
   
       5 . The method of  claim 1  wherein said reduction is carried out in the presence of a zwitterion.  
   
   
       6 . The method of  claim 5  wherein said zwitterion is an organic acid or an organic acid containing one or more heteroatomic functional groups.  
   
   
       7 . The method of  claim 6  wherein said organic acid is an amino acid.  
   
   
       8 . The method of  claim 7  wherein said organic acid is glycine, sarcosine, N,N-dimethylglycine, betaine or β-alanine, proline, serine, phosphonoacetic acid, N,N,N′,N′-ethylenediaminetetramethylenephosphonic acid or pyroglutamic acid.  
   
   
       9 . The method of  claim 1  wherein said reduction is carried out in the presence of a small, non-polymeric anion.  
   
   
       10 . The method of  claim 9  wherein said small anion is hydroxide, a halide, triflate or is derived from phosphorous acid  
   
   
       11 . The method of  claim 10  wherein said halide is iodide.  
   
   
       12 . The method of  claim 1  wherein said reduction is carried out in the presence of both a zwitterions and a small, non-polymeric anion.  
   
   
       13 . The method of  claim 1  wherein said transition metal ions are reduced with hydrogen, hydrazine, or borohydride reducing agent.  
   
   
       14 . The method of  claim 1  wherein the pH of said aqueous solution during said reduction is greater than 7.0  
   
   
       15 . The method of  claim 14  wherein said pH is about 10.  
   
   
       16 . The method of  claim 1  wherein said nanoparticles are cubic, tetrahedral, cubo-octrahedral, octrahedral, tetragonal, podal or a mixture thereof.  
   
   
       17 . The method of  claim 1 , including the isolation of said nanoparticles.  
   
   
       18 . The method of  claim 17  wherein said shaped nanoparticles are isolated on a carbon surface.  
   
   
       19 . The method of  claim 18  wherein said carbon is particulate carbon.  
   
   
       20 . The method of  claim 17  wherein ultrafiltration is employed in the isolation of said nanoparticles.  
   
   
       21 . The nanoparticles produced by the method of  claim 1 .  
   
   
       22 . The product produced by the method of  claim 18 .  
   
   
       23 . The product produced by the method of  claim 19.