Mesoporous nano-crystalline titania structures for hydrogen sensing

Abstract

A structure includes a substantially non-conductive frame having an exterior surface. The structure defines a plurality of passages that open to the exterior surface. Mesoporous material is disposed in the plurality of passages and is supported therein by the frame. In a method for making a mesoporous nanocrystalline titania hybrid material, a templating agent, an acid, and a titania precursor is mixed into a template liquid. A frame that defines a plurality of passages is placed into the template liquid. A solvent is evaporated from the template liquid, thereby forming a titania gel encapsulating the templating agent. The gel is heated to remove substantially the templating agent from the non-conductive frame and the titania, thereby leaving a mesoporous titania material.

1 . A structure, comprising: 
 a. a substantially non-conductive frame having an exterior surface and defining a plurality of passages that open to the exterior surface; and    b. mesoporous material disposed in the plurality of passages and supported therein by the frame.    
     
     
         2 . The structure of  claim 1 , wherein the frame comprises anodic aluminum oxide.  
     
     
         3 . The structure of  claim 2 , wherein the frame comprises an anodic aluminum oxide membrane.  
     
     
         4 . The structure of  claim 1 , wherein the passages have a diameter in a range of between 10 nm to 300 nm.  
     
     
         5 . The structure of  claim 4 , wherein the passages have a diameter in a range of between 20 nm to 210 nm.  
     
     
         6 . The structure of  claim 1 , wherein the mesoporous material comprises titania.  
     
     
         7 . The structure of  claim 1 , wherein the mesoporous material has a pore size in a range of between 2 and 20 nm.  
     
     
         8 . The structure of  claim 1 , wherein the mesoporous material comprises nanocrystals.  
     
     
         9 . The structure of  claim 1 , wherein the mesoporous material comprises a hybrid of nanocrystalline material and amorphous material.  
     
     
         10 . The structure of  claim 1 , further comprising a dopant added to the mesoporous material.  
     
     
         11 . The structure of  claim 10 , wherein the dopant is selected from a list consisting essentially of: Ce, Co, Fe, Mn, N, Nd, Pd, Pt, S, V, W, Eu, Cr, Tb, Er, Pr, and combinations thereof.  
     
     
         12 . A sensor of a target substance, comprising: 
 a. a mesoporous titania material disposed within a frame, the mesoporous titania material having mesopores that are capable of receiving the target substance therein, the mesoporous titania capable of interacting with the target substance, the mesoporous titania material having a property that is a function of interaction with the target substance; and    b. a component that senses a change in the property when the mesoporous nanocrystalline material is exposed to the target substance.    
     
     
         13 . The sensor of  claim 12 , wherein the target substance comprises hydrogen.  
     
     
         14 . The sensor of  claim 12 , wherein the property comprises an electrical resistance.  
     
     
         15 . The sensor of  claim 12 , wherein the frame comprises anodic aluminum oxide.  
     
     
         16 . The sensor of  claim 15 , wherein the frame comprises an anodic aluminum oxide membrane.  
     
     
         17 . The sensor of  claim 12 , wherein the mesoporous titania material has a pore size in a range of between 2 nm and 20 nm.  
     
     
         18 . The sensor of  claim 12 , wherein the mesoporous titania material comprises nanocrystals.  
     
     
         19 . The sensor of  claim 12 , wherein the mesoporous titania material comprises a hybrid of nanocrystalline material and amorphous material.  
     
     
         20 . The sensor of  claim 12 , further comprising a dopant added to the mesoporous titania material.  
     
     
         21 . The sensor of  claim 20 , wherein the dopant is selected from a list consisting essentially of: Ce, Co, Fe, Mn, N, Nd, Pd, Pt, S, V, W, and combinations thereof.  
     
     
         22 . A method for making a mesoporous nanocrystalline titania hybrid material, comprising the steps of: 
 a. mixing a templating agent into a solvent and an acid to form a template liquid;    b. adding a titania precursor to the template liquid;    c. placing into the titania precursor and the template liquid a substantially non-conductive frame having an exterior surface and defining a plurality of passages that open to the exterior surface and allowing the titania precursor and the template liquid to infiltrate into the plurality of passages;    d. evaporating the solvent from the template liquid, thereby forming a titania gel encapsulating the templating agent; and    e. heating the gel at a preselected temperature for a preselected period of time sufficient to remove substantially the templating agent from the non-conductive frame and the titania, thereby leaving a mesoporous titania material in the plurality of passages.    
     
     
         23 . The method of  claim 22 , wherein the templating agent is a material selected from a group consisting essentially of: a non-ionic block copolymer, a cationic surfactant, a zwitterionic surfactant and a non-ionic surfactant and an anionic surfactant, and combinations thereof.  
     
     
         24 . The method of  claim 22 , wherein the titania precursor is a material selected from a group consisting essentially of: titanium ethoxide, titanium chloride, titanium isopropoxide, titanium butoxide, titanium methoxide, titanium propoxide, and combinations thereof.  
     
     
         25 . The method of  claim 22 , wherein the heating step comprises heating the suspension in air at 400° C.