Self-organized porous WO3 formed in NaF electrolytes

In the present work we show that by anodization of W in NaF electrolytes porous tungsten oxide layers can be formed under a range of experimental conditions. The morphology of the layers depends strongly on the NaF concentration as well as the formation potential. Under optimized electrochemical conditions self-organized porous tungsten oxide layers can be formed. The single pore openings are very regular and have an average pore diameter of 100 nm.

[1]  Xiuli He,et al.  WO3 thin film prepared by PECVD technique and its gas sensing properties to NO2 , 2001 .

[2]  S. Badilescu,et al.  Study of sol–gel prepared nanostructured WO3 thin films and composites for electrochromic applications , 2003 .

[3]  C. E. Tracy,et al.  Electrochromic and optical properties of mesoporous tungsten oxide films , 2002 .

[4]  Marc Aucouturier,et al.  Anodic oxidation of titanium and TA6V alloy in chromic media. An electrochemical approach , 1999 .

[5]  C. Prater,et al.  Nanowire Array Composites , 1994, Science.

[6]  Patrik Schmuki,et al.  Formation of self-organized niobium porous oxide on niobium , 2005 .

[7]  Kenji Fukuda,et al.  Ordered Metal Nanohole Arrays Made by a Two-Step Replication of Honeycomb Structures of Anodic Alumina , 1995, Science.

[8]  Craig A. Grimes,et al.  Titanium oxide nanotube arrays prepared by anodic oxidation , 2001 .

[9]  M. Lohrengel,et al.  Nucleation and growth of anodic oxide films , 1983 .

[10]  Heon-Cheol Shin,et al.  Porous Tin Oxides Prepared Using an Anodic Oxidation Process , 2004 .

[11]  M. Pelino,et al.  Microstructural effect on NO2 sensitivity of WO3 thin film gas sensors Part 1. Thin film devices, sensors and actuators , 1996 .

[12]  Patrik Schmuki,et al.  Self-organized high aspect ratio porous hafnium oxide prepared by electrochemical anodization , 2005 .

[13]  Properties of annealed anodically etched porous Zn studied by scanning tunneling microscopy , 2003 .

[14]  A. Bard,et al.  The Electrochromic Process at WO3 Electrodes Prepared by Vacuum Evaporation and Anodic Oxidation of W , 1979 .

[15]  Craig A. Grimes,et al.  Fabrication of nanoporous tungsten oxide by galvanostatic anodization , 2003 .

[16]  D. Landolt,et al.  Anodic oxide growth on tungsten studied by EQCM, EIS and AES , 2004 .

[17]  Patrik Schmuki,et al.  Thick self-organized porous zirconium oxide formed in H2SO4/NH4F electrolytes , 2004 .

[18]  R. D. Nasby,et al.  Tungsten trioxide as an electrode for photoelectrolysis of water , 1976 .