Synthesis of metal-oxygen based materials with controlled porosity by oxidative dealloying

Abstract

Functional materials and methods for making the functional materials are provided. Also provided are methods for utilizing the functional materials in a variety of applications, including catalysis, adsorption, energy storage, and biomedical applications. The functional materials are made from metal alloys via an oxidative dealloying process that selectively removes one or more elements from the metal alloy and converts one or more of the remaining elements into a stable metal-oxygen matrix having a controlled porosity.

What is claimed is: 
     
       1. A method of forming a functional material, the method comprising:
 oxidatively dealloying a metal alloy comprising: a first element that is a transition metal, a post-transition metal, or a metalloid; and a second element that is a transition metal, a post-transition metal, a metalloid, or a non-metal, by exposing the metal alloy to an oxidizing environment comprising oxygen and, optionally, water, wherein the oxygen reacts with the first element to form a metal-oxygen compound of the first element that is stable in the oxidizing environment and reacts with the second element to form an unstable oxide of the second element that evaporates out of the metal alloy or that reacts with water in the oxidizing environment to form volatile hydroxides or oxy-hydroxides that evaporate out of the metal alloy, leaving a porous matrix comprising the metal-oxygen compound of the first element; and 
 subjecting the porous matrix to at least one post-dealloying processing step that changes a chemical property, physical property, or both, of the porous matrix. 
 
     
     
       2. The method of  claim 1 , wherein the metal-oxygen compound of the first element comprises a metal oxide of the first element. 
     
     
       3. The method of  claim 1 , wherein subjecting the porous matrix to at least one post-dealloying processing step that changes the chemical property, physical property, or both, of the porous matrix comprises applying a solid or liquid coating on at least a portion of a surface of the porous matrix. 
     
     
       4. The method of  claim 3 , wherein applying a solid or liquid coating on at least a portion of the surface of the porous matrix comprises chemically functionalizing at least a portion of the surface of the porous matrix by reacting the porous matrix with a chemical species to form a coating of the chemical species covalently bound to the surface of the porous matrix. 
     
     
       5. The method of  claim 3 , wherein the chemical species are organic molecules. 
     
     
       6. The method of  claim 5 , wherein the organic molecules are biomolecules. 
     
     
       7. The method of  claim 5 , wherein the organic molecules are organic polymer molecules. 
     
     
       8. The method of  claim 3 , wherein the chemical species comprises an electrolyte. 
     
     
       9. The method of  claim 3 , wherein applying a solid or liquid coating on at least a portion of the surface of the porous matrix comprises applying a catalytic metal or catalytic metal alloy to at least a portion of the surface of the porous matrix. 
     
     
       10. The method of  claim 9 , wherein the catalytic metal or catalytic metal alloy comprises gold, nickel, platinum, palladium, rhenium, ruthenium, iridium, or an alloy thereof. 
     
     
       11. The method of  claim 1 , wherein subjecting the porous matrix to at least one post-dealloying processing step that changes the chemical property, physical property, or both of the porous matrix comprises granulating the porous matrix, molding the porous matrix, or both. 
     
     
       12. The method of  claim 1 , wherein a portion of the metal alloy remains after the oxidative dealloying and further wherein subjecting the porous matrix to at least one post-dealloying processing step that changes the chemical property, physical property, or both of the porous matrix comprises separating at least a portion of the porous matrix from the remaining metal alloy and bonding the porous matrix to another substrate. 
     
     
       13. The method of  claim 12 , wherein subjecting the porous matrix to at least one post-dealloying processing step that changes the chemical property, physical property, or both of the porous matrix further comprises applying a solid or liquid coating on at least a portion of a surface of the porous matrix. 
     
     
       14. The method of  claim 1 , wherein the entire metal alloy is oxidatively dealloyed, such that the metal alloy is completely converted into the porous matrix. 
     
     
       15. The method of  claim 1 , wherein the porous matrix further comprises the second element in its elemental form, an oxide of the second element, an intermetallic compound of the second element, or a combination thereof. 
     
     
       16. The method of  claim 5 , wherein the first element and the second element are transition metal elements. 
     
     
       17. The method of  claim 1 , wherein the second element is a transition metal element. 
     
     
       18. The method of  claim 17 , wherein the second element is not molybdenum. 
     
     
       19. The method of  claim 17 , wherein the first element is a transition metal element or a post-transition metal element. 
     
     
       20. The method of  claim 19 , wherein the first element is a transition metal element. 
     
     
       21. The method of  claim 1 , wherein the second element is vanadium. 
     
     
       22. The method of  claim 1 , wherein: the metal alloy comprises a third element; the oxygen reacts with the third element to form a metal-oxygen compound of the third element that is stable in the oxidizing environment; and the porous matrix comprises the metal-oxygen compound of the first element and the metal-oxygen compound of the third element.