from the conferences organized by TANGER Ltd.
Molybdenum oxides exhibit numerous electronic properties thanks to the ability of Mo to possess various oxidation states and coordinations. Molybdenum oxides are thus attractive for applications in energy storage, conversion, electrochromic, gas sensing, or superconducting devices. The nanostructuring of molybdenum oxides, controlled through the preparation conditions, is advantageous for enhancing the material's properties. The so-called porous-anodic-alumina (PAA)-assisted anodizing, based on the anodic oxidation of a metal layer through a PAA overlayer, may also be a way to grow molybdenum-oxide nanocolumn arrays if their stability in water-containing electrolytes can be secured. To take on the challenge, we envisioned mixing MoOx with the oxide of a different metal (Nb), by placing a thin interlayer of Nb between the Al and Mo in the precursor thin-film stack. The arrays were prepared from the magnetron-sputtered Al/Nb/Mo trilayers by anodizing at 46 V, then re-anodizing to 180 V, followed by selective dissolution of the PAA overlayer. Detailed XPS characterization confirmed that various Mo species were present in the column material, with a total amount of Mo reaching 16 at.% (Mo+Nb = 100%). The fitting of the narrow-scan Nb 3d and Mo 3d spectra showed that Mo6+, Mo5+, and Mo4+, in various ratios, were present at the column surface material, whereas Nb2O5 was almost entirely stoichiometric. Further investigation is underway to understand the formation-structure-morphology relationship and explore the functional properties of the novel nanoarrays.
Keywords: Anodizing, porous anodic alumina, molybdenum oxides niobium pentoxide© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.