Reagent Delivery using a Membrane-Mediated Process

Abstract

Methods and apparatuses for using a semi-permeable membrane to deliver a reagent to a surface in a topographically selective manner are provided. The methods and apparatuses are particularly useful for removing sulfur-containing electrocatalysts from copper surfaces using a semi-permeable membrane to deliver an oxidizing agent to a catalyst-coated surface.

1 . An apparatus comprising:
 a) a fully or partially enclosed container;   b) a semi-permeable membrane having an internal surface and an external surface, wherein the membrane forms a surface of the fully or partially enclosed container; and   c) a reagent-containing fluid which at least partially fills the fully or partially enclosed container, wherein the reagent-containing fluid contacts at least a portion of the internal surface of the membrane.   
   
   
       2 . The apparatus of  claim 1 , wherein the reagent-containing fluid comprises an oxidizing agent. 
   
   
       3 . The apparatus of  claim 1 , wherein the semi-permeable membrane is selected from the group consisting of perfluorosulfonate ionomer membranes and perfluorocarboxylate ionomer membranes. 
   
   
       4 . A process comprising:
 a) providing an apparatus comprising:
 i) a fully or partially enclosed container; 
 ii) a semi-permeable membrane having an internal surface and an external surface, wherein the membrane forms a surface of the fully or partially enclosed container; and 
 iii) a reagent-containing fluid which at least partially fills the enclosed container, wherein the reagent-containing fluid contacts at least a portion of the internal surface of the membrane; 
   b) providing a workpiece having a surface and optionally an oxidizable or reducible compound adsorbed onto the surface of the workpiece;   c) contacting the surface of the workpiece with the external surface of the membrane; and   d) allowing at least a portion of the reagent to diffuse through the membrane to react with the workpiece surface or an oxidizable or reducible compound adsorbed onto the surface of the workpiece.   
   
   
       5 . The process of  claim 4 , wherein the reagent is an oxidizing agent. 
   
   
       6 . The process of  claim 5 , wherein the oxidizing agent is selected from the group consisting of ozone, hydrogen peroxide, peracids, Fe(NO 3 ) 3 , and Ce(NH 4 ) 2 (NO 3 ) 6 ). 
   
   
       7 . The process of  claim 4 , wherein the semi-permeable membrane is a perfluorosulfonate ionomer membrane or a perfluorocarboxylate ionomer membrane. 
   
   
       8 . The process of  claim 4 , wherein the oxidizable compound is 3-mercapto-1-propane sulfonic acid. 
   
   
       9 . The process of  claim 4 , further comprising coating the surface of the workpiece with a fluid film of a hydrocarbon or a halocarbon prior to contacting the workpiece with the external surface of the membrane. 
   
   
       10 . The process of  claim 4 , further comprising:
 e) contacting the workpiece with water.