Nanoporous anodic alumina layers obtained from novel deep eutectic solvent formulations

The possible fabrication of porous anodic oxide films on aluminium in ionic liquids based on choline dihydrogen citrate eutectic mixtures both with oxalic acid and isopropyl alcohol and ethylene glycol, has been investigated. The anodisation has been carried out in either potentiostatic or galvanostatic regime, at temperatures of 45-80 degrees C, for different process durations. Quite compact, uniform anodic alumina layers have been obtained. Based on AFM and SEM investigations, pore diameters between 50 and 80 nm and interpore distances in the range of 160-200 nm have been estimated, with values influenced by the electrolyte type and anodisation conditions. The highest anodisation rate of about 0.4 mu m min(-1) has been determined by applying operation temperatures of 60 degrees C. The recorded EIS spectra showed a pure capacitive behaviour and high anodic oxide resistances of 10(6)-10(7) omega cm(2) order.

Automated summary

The possible fabrication of porous anodic oxide films on aluminium in ionic liquids has been investigated in this study. The study found that the use of choline dihydrogen citrate eutectic mixtures with oxalic acid and isopropyl alcohol and ethylene glycol resulted in the production of compact and uniform anodic alumina layers. The size of the pores and the distance between them were influenced by the electrolyte type and anodisation conditions.