Nano-controlled barrier layer engineering for direct nanowire deposition in anodized aluminum oxide templates

The fabrication of nanocomposites within anodized aluminum oxide (AAO) templates presents significant challenges, including membrane separation, pore-bottom opening, and the high cost associated with conductive layer sputtering, each for efficient material deposition into nanopores for the synthesis of nanostructured materials. This study addresses these limitations with an integrated strategy that enables the uniform growth of nanostructured composite materials within AAO directly on the original aluminum substrate over areas as large as 50 cm² and with thicknesses up to 100 μm. The approach combines hard anodization in oxalic acid with stepwise barrier layer (BL) thinning and sacrificial layer anodization in saturated sulfuric acid, followed by controlled chemical etching under potentio-EIS monitoring. Structural and electrochemical analyses confirmed almost complete BL modification and pore opening while preserving connectivity to the substrate. As a proof of concept, uniform Ni nanowire arrays with thicknesses up to 100 μm were successfully deposited by DC electrodeposition over large areas. This method eliminates the need for membrane detachment and conductive sputtering, thereby offering a scalable and cost-effective pathway for nanocomposite fabrication.