Method for the preparation of nanostructures and nanowires

Abstract

A process for producing porous nanostructures suitable for the manufacture of nanowires and processes for manufacturing of the nanowires by using said nanostructure are disclosed. The process for obtaining the nanostructure of the invention comprises the steps of cleaning and polishing the surface of an aluminum metal substrate, forming a porous oxide layer bearing nanoholes on said aluminum substrate, immersing the porous structure into a basic zincate solution for etching the bottoms and walls of the nanoholes and depositing a thin and substantially pure Zn film extending from the bottom of the nanoholes through the aluminum substrate. Nanowires can be fabricated by the step of utilizing so obtained etched nanostructure as an electrode and subjecting the same to a metal electro-deposition operation.

1 . A process for manufacturing of nanowires comprising the steps of;
 cleaning and polishing the surface of an aluminum metal substrate, and then forming a porous oxide layer bearing nanoholes on the aluminum substrate,   immersing the porous structure into a basic zincate solution for etching the bottoms and walls of the nanoholes and depositing a Zn film from inner walls of the pores through the aluminum substrate, wherein said solution comprising Zn(OH) 2  and a strong base selected from the group consisting of NaOH, KOH, Ba(OH) 2 , Ca(OH) 2 , LiOH, RbOH, CsOH and Sr(OH) 2 , and   utilizing the etched nanostructure as an electrode and subjecting the same to a metal electro-deposition process.   
     
     
         2 . A process according to  claim 1 , wherein the porous oxide layer is formed by means of two anodization steps for providing regular arrays of nanoholes. 
     
     
         3 . A process for producing a porous nanostructure according to  claim 2  wherein said anodization steps are carried out in the presence of an acidic electrolytic solution selected from the group consisting of aqueous sulfuric acid, oxalic acid, phosphoric acid and chromic acid solutions. 
     
     
         4 . A process according to  claim 3  wherein concentration of said acidic solution varies in the range of 1% to 50%, more preferably 3% to 15% (v/v). 
     
     
         5 . A process for producing a porous nanostructure according to  claim 1  wherein the Zn(OH) 2 /strong base ratio in the zincate solution varies in the range of 0.1 to 1.8, more preferably in the range of 0.4 to 0.8 by weight. 
     
     
         6 . A process according to  claim 1  wherein the metal deposited within the pores of the nanostructure is selected from the group consisting of Ni, Fe and Co. 
     
     
         7 . A process according to  claim 1 , wherein the electro-deposition is carried out in a current density ranging from 0.1 to 20 A/dm 2 , more preferably 0.2 to 2 A/dm 2 . 
     
     
         8 . A process according to  claim 1 , wherein the electro-deposition step is carried out in the presence of an electrolytic solution comprising NiSO 4  and a weak acid selected from the group consisting of H 3 BO 3 , H 3 PO 4 , CH 3 COOH, HF, CH 3 COCOOH and C 5 H 5 NCOOH. 
     
     
         9 . A process for producing nanowires according to  claim 8 , wherein the ratio of NiSO 4 /weak acid varies in the range of 1 to 50, more preferably 5 to 8 (w/w).