Well-defined meso- to macro-porous film of tin oxides formed by an anodization process

Anodically formed tin oxide typically displays a self-ordered porous structure with a large degree of cracking. In addition, its surface pores are frequently closed, especially in the case where the deposited tin film is anodized. Herein, we report a simple way of eliminating virtually all the inner cracks and ensuring that the surface pores are totally open, leading to well-defined one-dimensional anodic tin oxide. The current efficiency ratio of oxygen gas generation to tin oxide formation and the amount of charge allocated for pore initiation are suggested to be the key factors affecting the internal crack development and pore opening, respectively. Pulsed anodization proved to be quite an effective way to create a well-defined structure with few inner cracks and completely open pores.

► The origin of the internal flaws and closed surface pores frequently observed in typical anodic porous tin oxides was systematically explored.
► It was suggested that the current efficiency ratio of oxygen gas generation to tin oxide formation and the amount of charge allocated for pore initiation are the key factors affecting the internal crack development and pore opening, respectively.
► Pulsed anodization proved to be quite an effective way to create a well-defined structure with few inner cracks and completely open pores.