Preparation columnar porous

Porous anodic aluminum oxide (AAO) which characterized by a closely packed regular array of columnar cells is well-established and widely-used material for formation of nanostructures for SERS [2,3]. Particularly, promising SERS-active substrates were prepared by vacuum deposition of silver onto commercially available alumina filters with open pores of 200-300 nm diameters [4], Nanowires and nanorods have been fabricated by filling the AAO pores with transition- or noble-metals. However, due to multistage procedure these nanoarrays being sensitive are rather complicated in fabrication. 

M.M. Yusuf et al. have reported mesoporous Ti02 films with controlled pore sizes prepared by smfactant templating sol-gel method and its photocatalytic activity. The porous films of anatase with rectangular and columnar structure were obtained by annealing after immersion of the wet gel films in benzyltrimethylammonium chloride- and cetyltrimethyl-ammonium chloride-solutions, respectively. They concluded that the microstructure of the sol-gel derived films can be controlled by changing the type of surfactant species and the concentration of surfactant solutions. The photocatalytic activity of their films for the oxidation of NO , was improved by the surfactant modification (Yusuf, 2002). 

---