One-step synthesis of freestanding and translucent ZrO2 nanotube membranes by direct electrochemical anodization

[Display omitted] •A one-step direct anodization method has been used to obtain ZrO2 nanotube membranes.•The obtained ZrO2 with cubic crystalline structure without thermal annealing processes.•The ZrO2-NT membranes are attractive for applications in biotechnology, sensors, and catalysis. One-step synthesis of freestanding zirconium oxide nanotube (ZrO2-NT) membranes was obtained by direct electrochemical anodization of zirconium (Zr) substrates in aqueous electrolytes (mixture of 1 M (NH4)2SO4 and 0.75 M NH4F). The maximum membrane area was 9 cm2 and showed translucency from 400 to 700 nm. The ZrO2-NTs have an external diameter of ∼80 nm, an internal diameter of ∼55 nm, and a length of ∼22.5 μm. Moreover, the ZrO2-NTs showed a cubic crystal structure after anodization. The results are highly promising for applications requiring independent ZrO2 nanotube membranes.