Reduction of nanoparticle deposition during fabrication of porous anodic alumina

In this paper, we present evidences of nanoparticle deposition on porous anodic alumina (PAA) surface under different anodizing conditions, and discuss the formation mechanism of precipitations. Low-temperature anodization, vigorous stirring and ultrasound-assisted anodization are proposed to reduce the hydrolysis product or hinder its deposition on the surface as well as inside nanopores of PAA. It is discovered that the ultrasound is very efficient to prevent the deposition of Al3+ hydrolysis product on PAA. This study is of great value for realizing ordered PAAs with clean surface.

► Nanoparticle deposition during anodizing aluminum is revealed.
► The Al3+ ions come out continuously, and some hydrolyze to be solid deposition.
► Low temperature, stirring and ultrasound are used to reduce the deposition.
► Ultrasound is very effective to reduce nanoparticle deposition.