Fuel cell electrodes

Abstract

A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

1 . A process comprising:
 patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode;   wherein:
 the adsorbate comprises a calix[n]arene, cyclodextrine, a cucurbit[n′]uril, a porphyrin, a crown ether, a calix[n]pyrrole, a pyrogallol[n]arene, and a calix[4]resorcinarene, where n is 4, 6, or 8 and n′ is the number of glycoluril units and is 5, 6, 7, or 8; 
 and the patterned platinum group metal-based electrode comprises platinum group metal sites blocked with the adsorbate and platinum group metal sites which are not blocked. 
   
     
     
         2 . The process of  claim 1 , wherein the platinum group metal-based electrode comprises Pt, Pd, Ir, or Rh, or a Pt alloy with one or more of Co, Ni, Fe, Ti, Cr, V, or Mn. 
     
     
         3 . The process of  claim 1 , wherein the platinum group metal-based electrode comprises Pt(100), Pt(111), Pt(1099), or polycrystalline Pt. 
     
     
         4 . The process of  claim 1 , wherein the adsorbate comprises calix[4]arene. 
     
     
         5 . The process of  claim 1 , wherein the adsorbate comprises a calix[n]arene which is a thiol-modified calix[n]arene. 
     
     
         6 . The process of  claim 1 , wherein the patterning comprises heating the platinum group metal-based electrode to an annealing temperature from about 500 K to about 1500 K under a reducing atmosphere, cooling the electrode, and immersing the electrode in a solution comprising the adsorbate. 
     
     
         7 . The process of  claim 6 , wherein the annealing temperature is from about 1000 K to about 1200 K. 
     
     
         8 . The process of  claim 6 , wherein the reducing atmosphere comprises hydrogen gas. 
     
     
         9 . The process of  claim 6 , wherein the reducing atmosphere comprises hydrogen gas and an inert gas. 
     
     
         10 . The process of  claim 9 , wherein the inert gas comprises He, Ne, Ar, or N 2 . 
     
     
         11 . The process of  claim 6 , wherein the electrode is cooled to about ambient temperature. 
     
     
         12 . The process of  claim 6 , wherein the solution comprises a solvent and the adsorbate. 
     
     
         13 . The process of  claim 6 , wherein the solution further comprises an organic solvent. 
     
     
         14 . The process of  claim 13 , wherein the organic solvent comprises tetrahydrofuran, diethyl ether, methyl butyl ether, 1,2-dichlorobenzene, 1,4-dichlorobenzene , dimethylsulfoxide, dimethylformamide, ethanol, methanol or a mixture of any two or more thereof. 
     
     
         15 . The process of  claim 13 , wherein a concentration of the calix[n]arene in the organic solvent is from about 10 μM to about 500 μM. 
     
     
         16 . The process of  claim 1 , wherein from about 90% to about 99% of the Pt metal sites are blocked by the calix[n]arene molecules and from about 10% to about 1% of the Pt metal sites are not blocked by the calix[n]arene molecules. 
     
     
         17 . A platinum group metal-based electrode produced by the process of  claim 1 . 
     
     
         18 . A platinum group metal-based electrode of  claim 17  which comprises Pt(100), Pt(111), Pt(1099), or polycrystalline Pt. 
     
     
         19 . An electrode comprising a platinum group metal-based substrate comprising adsorbate molecules wherein a portion of the platinum group metal sites are blocked by adsorbate molecules and a portion of the platinum group metal sites are unblocked. 
     
     
         20 . The electrode of  claim 19 , wherein from about 90% to about 99% of the Pt metal sites are blocked by the adsorbate and from about 10% to about 1% of the Pt metal sites are free of adsorbate. 
     
     
         21 . The electrode of  claim 19 , platinum group metal-based substrate comprises Pt, Pd, Ir, or Rh, or a Pt alloy with one or more of Co, Ni, Fe, Ti, Cr, V, or Mn. 
     
     
         22 . The electrode of  claim 19 , wherein the platinum group metal-based substrate comprises Pt(100), Pt(111), Pt(1099), or polycrystalline Pt. 
     
     
         23 . A fuel cell comprising the electrode of  claim 19 .