Electrodes containing iridium nanoparticles for the electrolytic production of oxygen from water

Abstract

Electrodes employing as active material iridium nanoparticles synthesized by a novel route are provided. The nanoparticle synthesis is facile and reproducible, and provides iridium nanoparticles of very small dimension and high purity for a wide range of metals. The electrodes utilizing these nanoparticles have excellent efficiency catalyzing the electrolytic production of oxygen from water.

What is claimed is: 
     
         1 . An electrode comprising iridium nanoparticles, the iridium nanoparticles synthesized by a method comprising:
 adding surfactant to a reagent complex according to Formula I,
   Ir 0 ·X y   I,
 
   wherein Ir 0  is zero-valent iridium, X is a hydride, and y is an integral or fractional value greater than zero.   
     
     
         2 . The electrode of  claim 1  wherein the reagent complex is obtained by a process that includes a step of:
 ball milling a mixture that includes a hydride and a preparation composed of iridium. 
 
     
     
         3 . The electrode of  claim 1  wherein the hydride is lithium borohydride. 
     
     
         4 . The electrode of  claim 1  wherein the iridium nanoparticles have an average maximum dimension less than 100 nm. 
     
     
         5 . The electrode of  claim 1  wherein the iridium nanoparticles have an average maximum dimension less than 10 nm. 
     
     
         6 . The electrode of  claim 1  wherein the iridium nanoparticles have an average maximum dimension less than 5 nm. 
     
     
         7 . The electrode of  claim 1  which catalyzes the half-cell reaction:
   2H 2 O O 2 +4H + +4e − .