Method for enhancing surface area of bulk metals

Abstract

A novel method for enhancing the surface area of bulk metals is hereto presented. The method comprising according to one embodiment the steps of dispersing metal nano particles in a solution comprising water-soluble polymeric materials; introducing the a cathode substrate inside the dispersed solution; and than applying electric current to this cathode, so it is coated by said highly dispersed nano particles. According to yet another embodiment the method comprising the steps of coating bulk metals with nano particles made of a predetermined metal alloy; and than chemically leaching at least one of the metals such as a very high surface area of said coated metal is obtained. The present invention also presents bulk metals e.g., electrodes, coated by means of the methods defined above.

1 . A method for enhancing surface area of bulk metals by nano particles, comprising; 
 a. dispersing metal nano particles in a solution comprising water-soluble polymeric materials;    b. introducing the bulk metal inside the dispersed solution; and,    c. applying electric current to a bulk metals, such as the bulk metal is at least partially coated by said highly dispersed nano particles.    
     
     
         2 . The method according to  claim 1 , wherein the metal nano particles are produced by a metallurgical-chemical method.  
     
     
         3 . The method according to  claim 1 , wherein the nano particles are colloidal nano particles obtained by wet-chemical reduction method.  
     
     
         4 . The method according to  claim 1 , wherein the water-soluble polymeric materials are selected from PVP, ammonium salts of poly-carbonic acids, polyamines, polyglycols, polyalcohols, any water-soluble polymer or any combination thereof.  
     
     
         5 . The method according to  claim 1 , wherein the dispersion is obtained in water, water miscible solvents, water miscible organic solvents or any mixture thereof.  
     
     
         6 . The method according to  claim 1 , wherein the dispersion is provided by a means of an ultrasonic homogenizer probe.  
     
     
         7 . The method according to  claim 1 , wherein the dispersion is provided by a means of mechanical high rpm or high sheering dispersing equipment, selected from rotor or rotor/stator devices.  
     
     
         8 . The method according to  claim 1 , wherein the dispersion is provided by a means of a high pressure homogenizer or any other dispersing equipment  
     
     
         9 . The method according to  claim 1 , wherein the bulk material to be coated by nano particles is a cathode.  
     
     
         10 . The method according to  claim 1 , wherein the bulk material to be coated by nano particles is an anode.  
     
     
         11 . The method according to  claim 1 , wherein the electric current to the cathode to be coated is ranges between 5 to 50 V and between 0.0001 to 0.1 A for 1 to 240 minutes.  
     
     
         12 . The method according to  claim 11 , wherein the electric current to a cathode to be coated is ranges between 10 to 30 V and between 0.001 to 0.04 A for 1 to 120 minutes.  
     
     
         13 . The method according to  claim 1 , comprising; 
 a. dissolving water-soluble metal salt or salts in solutions of water-soluble polymeric materials;    b. introducing the bulk metal inside the solution; and    c. applying electric current to a bulk material such as the bulk metal is at least partially coated by metal nano particles.    
     
     
         14 . The method according to  claim 13 , wherein the solution is obtained in water, water miscible solvents, water miscible organic solvents or any mixture thereof.  
     
     
         15 . The method according to  claim 13 , wherein the electric current to a cathode to be coated is ranges between 0.1 to 5 V and between 0.1 to 10 A for 1 to 120 minutes.  
     
     
         16 . A method for enhancing surface area of bulk metals by nano particles, comprising; 
 a. forming a nano-structure comprising metal alloy;    b. coating bulk metals with said alloy; and    c. chemically leaching one of the metals to form such a very high surface area of coated bulk metal.    
     
     
         17 . A method according to  claim 1 , comprising; 
 a. forming a nano-structure comprising metal alloy;    b. coating bulk metals with said alloy; and    c. chemically leaching one of the metals to form such a very high surface area of coated bulk metal.    
     
     
         18 . The method according to  claim 17 , adapted for silver-aluminum system, comprising silver in concentration range of 5 to 30% (w/w) and aluminum in concentration range of 70 to 95%.  
     
     
         19 . The method according to  claim 17 , wherein the coated bulk metal is subjected to a heat treatment in the range of 100° C. to 650° C.  
     
     
         20 . The method according to  claim 17 , wherein the leaching solution comprises sodium or potassium hydroxide in the concentration range of 10% to 60% (w/w).  
     
     
         21 . The method according to  claim 20 , wherein the leaching solution comprises sodium or potassium hydroxide in the concentration range of 25% to 35% (w/w).  
     
     
         22 . The method according to  claim 20 , wherein the leaching is provided in the range of 25° C. to 45° C.  
     
     
         23 . The method according to  claim 17 , wherein the leaching is provided in the temperature ranges of about 25 to about 70° C.  
     
     
         24 . The method according to  claim 17 , wherein the metal alloys comprising metals selected from silver, aluminum, nickel, gold, platinum or palladium.  
     
     
         25 . The method according to  claim 17 , wherein the heat treatment is provided by a means selected from heating with air at a temperature of 200° C. to 500° C.; heating in vacuum at a temperature of 150° C. to 300° C.; heating in a liquid of basic pH at a temperature of about 100° C. to 120° C.; heat-treatment of the foil strips at about 550° or any combination thereof.  
     
     
         26 . The method according to  claim 17 , additionally comprising a washing step, wherein the coated bulk metal is washed by effective measure of water.  
     
     
         27 . The method according to  claim 1 , wherein the bulk metal is selected from electrical conductors, electrodes, wires, filaments, conductive substrate or any combination thereof.  
     
     
         28 . The method according to  claim 17 , wherein the bulk metal substrate is made of metallic composition or metal alloy of at least two metallic compositions, composite materials, conductive polymers, non-conductive materials, aluminum-containing materials, metal oxides, metal carbides or any combination thereof.  
     
     
         29 . Bulk metals of enhanced surface area at least partially coated by nano particles or structures produced in the method according to  claim 1 .  
     
     
         30 . A bulk metal substrate of enhanced surface area, at least partially coated by nano particles or structures according to  claim 1 , selected from electrical conductors, electrodes, wires, filaments, made of metallic composition or metal alloy of at least two metallic compositions, composite materials, conductive polymers, non-conductive materials, aluminum-containing materials or any combination thereof.  
     
     
         31 . The bulk metal substrate according to  claim 1 , coated by more than one layer of nano particles or nano structures