Synthesis of Self‐Ordered Tantalum‐Niobium Mixed Oxide Nanotubes and Their Use for Clean Hydrogen Production

Abstract We report on the first fabrication of vertically‐oriented tantalum‐niobium mixed oxide nanotube arrays (Ta−Nb−O NTs) via one‐step anodization of Ta−Nb alloy sheet in NH₄F‐containing electrolytes. The synthesized Ta−Nb−O NTs were fully characterized via X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), high‐resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS). The prepared nanotubes have an average diameter of ∼35 nm with a wall thickness ∼15 nm and a length ∼1.0 μm. The photoactivity of the fabricated Ta−Nb−O NTs was tested toward the photocatalytic hydrogen production, revealing a steady rate with no indication of activity poisoning. The amount of hydrogen produced can be as high as 150 μL/cm² after 5 h of illumination, which is much higher than that reported for most metal oxides. Therefore, the demonstrated platform of Ta−Nb−O nanotube arrays holds promise for a variety of solar energy applications.