Multiple walled nested coaxial nanostructures

Abstract

Multiple walled nested coaxial nanostructures, methods for making multiple walled nested coaxial nanostructures, and devices incorporating the coaxial nanostructures are disclosed. The coaxial nanostructures include an inner nanostructure, a first outer nanotube disposed around the inner nanostructure, and a first annular channel between the inner nanostructure and the first outer nanotube. The coaxial nanostructures have extremely high aspect ratios, ranging from about 5 to about 1,200, or about 300 to about 1200.

1 . A multiple walled nested coaxial nanostructure comprising:
 an inner nanostructure;   a first outer nanotube disposed around the inner nanostructure; and   a first annular channel between the inner nanostructure and the first outer nanotube,   wherein the aspect ratio of the coaxial nanostructure ranges from about 5 to about 1200.   
     
     
         2 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure is a nanorod or a nanotube. 
     
     
         3 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure is a nanotube. 
     
     
         4 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure, the first outer nanotube, or both comprise a conductor. 
     
     
         5 . The coaxial nanostructure of  claim 4 , wherein the conductor is a metal or a conducting metal nitride or conducting metal oxide. 
     
     
         6 . The coaxial nanostructure of  claim 4 , wherein the conductor is selected from Ti, Au, Pt, Al, Cu, Ag, W or a nitride thereof. 
     
     
         7 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure, the first outer nanotube, or both comprise an insulator. 
     
     
         8 . The coaxial nanostructure of  claim 7 , wherein the insulator is a metal oxide or insulating metal nitride or semiconductor oxide. 
     
     
         9 . The coaxial nanostructure of  claim 7 , wherein the insulator is selected from SiO 2 , HfO 2 , ZrO 2 , Al 2 O 3 , or TiO 2 . 
     
     
         10 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure, the first outer nanotube, or both comprise a semiconductor. 
     
     
         11 . The coaxial nanostructure of  claim 10 , wherein the semiconductor is ZnO or TiO 2 . 
     
     
         12 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure and the first outer nanotube independently comprise a metal oxide selected from ZnO, SiO 2 , HfO 2 , ZrO 2 , Al 2 O 3 , or TiO 2 . 
     
     
         13 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure and the first outer nanotube comprise the same metal oxide selected from ZnO, SiO 2 , HfO 2 , ZrO 2 , Al 2 O 3 , or TiO 2 . 
     
     
         14 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure comprises ZrO 2 , and the first outer nanotube comprises ZrO 2 . 
     
     
         15 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure comprises HfO 2 , and the first outer nanotube comprises HfO 2 . 
     
     
         16 . The coaxial nanostructure of  claim 1 , further comprising a second outer nanotube disposed around the first outer nanotube and a second annular channel between the first outer nanotube and the second outer nanotube. 
     
     
         17 . The coaxial nanostructure of  claim 16 , wherein the inner nanostructure, the first outer nanotube, and the second outer nanotube independently comprise a metal oxide selected from ZnO, SiO 2 , HfO 2 , ZrO 2 , Al 2 O 3 , or TiO 2 . 
     
     
         18 . The coaxial nanostructure of  claim 16 , wherein the inner nanostructure, the first outer nanotube, and the second outer nanotube comprise the same oxide or metal oxide selected from ZnO, SiO 2 , HfO 2 , ZrO 2 , Al 2 O 3 , or TiO 2 . 
     
     
         19 . The coaxial nanostructure of  claim 16 , wherein the inner nanostructure comprises ZrO 2 , the first outer nanotube comprises ZrO 2 , and the second outer nanotube comprises ZrO 2 . 
     
     
         20 . The coaxial nanostructure of  claim 16 , wherein the inner nanostructure comprises HfO 2 , the first outer nanotube comprises HfO 2 , and the second outer nanotube comprises HfO 2 . 
     
     
         21 . The coaxial nanostructure of  claim 1 , wherein the cross-section of the coaxial nanostructure is substantially circular upon release from the nanoporous template. 
     
     
         22 . The coaxial nanostructure of  claim 1 , wherein the coaxial nanostructure is coupled to a substrate. 
     
     
         23 . The coaxial nanostructure of  claim 1 , wherein the coaxial nanostructure is coupled to a nanoporous substrate, and further wherein the coaxial nanostructure is disposed within a pore of the nanoporous substrate. 
     
     
         24 . The coaxial nanostructure of  claim 1 , wherein the coaxial nanostructure is coupled to a porous anodic aluminum oxide substrate, and further wherein the coaxial nanostructure is disposed within a pore of the porous anodic aluminum oxide substrate. 
     
     
         25 . An array comprising two or more coaxial nanostructures according to  claim 1 . 
     
     
         26 . A device comprising the coaxial nanostructure of  claim 1 . 
     
     
         27 . The device of  claim 26 , wherein the device is a chemical sensor, a photovoltaic cell, or a photonic crystal. 
     
     
         28 . The coaxial nanostructure of  claim 1 , wherein the inner nanostructure, the first outer nanotube, or both are substantially free of carbon. 
     
     
         29 . The coaxial nanostructure of  claim 1 , wherein the width of the annular channel ranges from about 5 nm to about 30 nm. 
     
     
         30 . The coaxial nanostructure of  claim 1 , wherein the annular channel comprises air. 
     
     
         31 . The coaxial nanostructure of  claim 1 , wherein the annular channel comprises a sacrificial material disposed within the annular channel. 
     
     
         32 . The coaxial nanostructure of  claim 1 , wherein the annular channel comprises a sacrificial material disposed within the annular channel, the sacrificial material capable of being dissolved by a chemical etchant. 
     
     
         33 . The coaxial nanostructure of  claim 1 , wherein the annular channel comprises Al 2 O 3  disposed within the annular channel. 
     
     
         34 . A method of making a coaxial nanostructure comprising:
 forming a layer of a first material on an inner surface of a nanopore of a nanoporous substrate using atomic layer deposition;   forming a first layer of a sacrificial material on the layer of the first material using atomic layer deposition; and   forming a layer of a second material on the first layer of the sacrificial material using atomic layer deposition,   wherein a coaxial nanostructure is provided, the coaxial nanostructure having an aspect ratio ranging from about 300 to about 1200.   
     
     
         35 . The method of  claim 34 , wherein the nanoporous substrate is anodic aluminum oxide. 
     
     
         36 . The method of  claim 34 , wherein the sacrificial material comprises Al 2 O 3 . 
     
     
         37 . The method of  claim 34 , wherein the first material, the second material, or both comprise a conductor. 
     
     
         38 . The method of  claim 34 , wherein the first material, the second material, or both comprise an insulator. 
     
     
         39 . The method of  claim 34 , wherein the first material, the second material, or both comprise a semiconductor. 
     
     
         40 . The method of  claim 34 , wherein the first material and the second material independently comprise a metal oxide selected from ZnO, SiO 2 , HfO 2 , ZrO 2 , or TiO 2 . 
     
     
         41 . The method of  claim 34 , further comprising removing the sacrificial layer by chemical etching. 
     
     
         42 . The method of  claim 34 , further comprising removing the nanoporous substrate. 
     
     
         43 . The method of  claim 34 , further comprising removing the nanoporous substrate by chemical etching. 
     
     
         44 . The method of  claim 34 , further comprising forming a second layer of a sacrificial material on the layer of the second material and forming a layer of a third material on the second layer of the sacrificial material. 
     
     
         45 . An oxygen sensor comprising the coaxial nanostructure of  claim 1 . 
     
     
         46 . A sensor capable of simultaneously detecting a plurality of chemicals comprising the coaxial nanostructure of  claim 1 . 
     
     
         47 . The coaxial nanostructure of  claim 1 , wherein the coaxial nanostructure is disposed within a pore of a porous substrate. 
     
     
         48 . The coaxial nanostructure of  claim 1 , wherein the porous substrate is porous silicon or porous anodized aluminum oxide. 
     
     
         49 . The multiple walled nested coaxial nanostructure, wherein the aspect ratio is about 300 to about 1,200. 
     
     
         50 . A method of making a coaxial nanostructure comprising:
 forming a layer of a first material on an inner surface of a nanopore of a nanoporous substrate using atomic layer deposition;   forming a first layer of a sacrificial material on the layer of the first material using atomic layer deposition; and   forming a layer of a second material on the first layer of the sacrificial material using atomic layer deposition,   wherein a coaxial nanostructure is provided, the coaxial nanostructure having an aspect ratio ranging from about 5 to about 1200.   
     
     
         51 . A multiple walled nested coaxial nanostructure comprising:
 an inner nanostructure;   a first outer nanotube disposed around the inner nanostructure; and   a first annular channel between the inner nanostructure and the first outer nanotube,   wherein the aspect ratio of the coaxial nanostructure ranges from about 300 to about 1200.   
     
     
         52 . A method of making a coaxial nanostructure comprising:
 forming a layer of a first material on an inner surface of a nanopore of a nanoporous substrate or a macroporous substrate using atomic layer deposition;   forming a first layer of a sacrificial material on the layer of the first material using atomic layer deposition; and   forming a layer of a second material on the first layer of the sacrificial material using atomic layer deposition,   wherein a coaxial nanostructure is provided, the coaxial nanostructure having an aspect ratio ranging from about 5 to about 1200.   
     
     
         53 . The method of  claim 52 , wherein the macroporous substrate is used. 
     
     
         54 . The method of  claim 52 , wherein the substrate is silicon.