Fabrication Of Porous Anodic Aluminum Oxide Templates At Low Temperature And The Construction Of Templates With Hierarchical Pore Structure

Porous anodic aluminum oxide(PAAO)template is a kind of closely ordered circular pore structure material,which has the advantages of controllable structural parameters,simple process,low cost and good repeatability,making it one of the most commonly used templates for preparing various nanostructure materials,widely used in various fields,including sensors,catalysis and biomedicine.In this article,a mixed solution of 0.3 mol/L oxalic acid solution and absolute ethanol(1:1,V/V)(electrolyte Ⅰ)or 0.3 mol/L oxalic acid solution(electrolyte Ⅱ) is used as the anodization electrolyte.The anodization temperature was-20 to 15 ℃,and the PAAO templates were prepared by applying an anodization voltage of 30 to 50 V and its internal mechanism was studied in detail.In addition,a transverse micron scale crack template is obtained by spin coating polymer CA600(nail polish) on the surface of the smooth aluminum sheet.Then,in the electrolyte Ⅱ at 15 °C,a voltage of 30 to 50 V was applied to anodize the entire sample,and nano-scale pores were further formed on the aluminum surface in the cracks.Finally,a template with a hierarchical pore structure was obtained.In this paper,the experimental factors affecting the microstructure of the templates with hierarchical pore structure were studied and analyzed in detail.(1)In electrolyte Ⅰ or electrolyte Ⅱ at-20 to 0 ℃,anodization voltage of 40 to 50 V is applied for low temperature anodization.At an anodization temperature of -20 °C,the anodization process of the PAAO templates achieved a very slow growth rate.In this paper,the mechanism of the PAAO templates obtaining very slow growth rate were studied in detail,and the effect of low anodization temperature on PAAO templates were analyzed.(2)In electrolyte Ⅰ,under the condition of anodization temperature of-20 to 0 ℃,the PAAO templates were prepared by applying anodization voltage of 40 to 50 V.The regularity of the obtained PAAO templates were analyzed.An improved two-step anodization method was proposed to prepare PAAO templates with high regularity at low temperature.(3)A crack template was formed by spin coating polymer CA600 on the smooth surface of aluminum sheet,and the heat treatment was carried out on the samples after spin coating.Then,in the electrolyte Ⅱ at 15 ℃,anodization voltage of 30 to 50 V was applied to prepare the templates with hierarchical pore structure,and its growth mechanism was studied.(4)In electrolyte Ⅱ at 15 ℃,the structural parameters of the templates with hierarchical pore structure were adjusted by changing the experimental conditions,and the hierarchical pore structure templates with different structural parameters were successfully prepared.In this paper,the effects of spin-coating time,spin-coating speed,and anodization voltage on the micro-structure of the templates with hierarchical pore structure are studied in detail.