Two-step anodization of maltilayer TiO₂ nanotube and its photocatalytic activity under UV light

Abstract

A double-layer TiO₂ nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was conducted in a formamide based electrolyte, which allowed the second layer of nanotube growing directly underneath the first one. From FESEM investigation we found that the thickness of second layer corresponded to the anodization time, the increasing of which would lead to the excessive etching on the first layer. The first layer protected the lower one from fluoride corrosion during anodization process. The double layer TiO₂ nanotube arrays showed no benefit to photodegradation effect in methyl orange degradation experiments.

Keywords

double-layer TiO₂ nanotube / anodization / photocatalysis / methyl orange degradation

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