Fe sem 4800sem

The nanotubular structures were obtained on 0.125 mm thick Ti foil (99.6% pure temper annealed, ADVENT, Oxford, UK). The Ti foils were cut into 2.5 × 2.5 cm and cleaned by successive ultrasonication (acetone, ethanol, water) and dried in a N₂ stream.
The anodization experiments (two-electrode configuration) were performed in optimized conditions [46 (link)], briefly close-packed nanotubes with 20 nm intertube spacing (TNT20)—Glycerol (>99.7% p.a. Roth, Karlsruhe, Germany):H₂O (70:30 vol.%) + 0.5 wt.% NH₄F (>98% p.a. Roth, Karlsruhe, Germany), 20 V, and spaced nanotubes with 80 nm intertube spacing (TNT80)—Diethylene glycol (>99.5% p.a. Roth, Karlsruhe, Germany) + 4 wt.% HF (HF 40%, Sigma Aldrich, Germany) + 0.3 wt.% NH₄F + 7 wt.% H₂O, 27 V, 4 h, 30 °C. For additional information, see experimental details in previous work [46 (link)].
The morphology of the samples was evaluated by scanning electron microscope (SEM, FE-SEM 4800SEM, Hitachi, Japan). The contact-angle measurements were performed by a contact angle measurement system (DSA100, Kruss, Germany), as described previously [109 (link)].

Samples morphology was characterized by scanning electron microscope (SEM, FE-SEM 4800SEM, Hitachi, Japan) coupled with an energy-dispersive X-ray Spectroscope (EDAX Genesis, fitted to the SEM chamber), while their chemical composition and chemical state was investigated by using X-ray photoelectron spectroscopy (XPS, PHI 5600, Physical Electronics, US)—peaks were shifted to C1s 284.8eV.