Anodising of titanium in methanesulphonic acid to form titanium dioxide nanotube arrays

Titanium foil was anodised in an aqueous solution of methanesulphonic acid at a concentration up to 9·0 mol dm−3 to form titanium dioxide nanotube arrays at 295 K. The effect of ammonium fluoride concentration (0·01–1·0 wt‐%), applied cell voltage (1–30 V dc) and anodising time (1–24 h) on the formation of nanotubes was investigated. Surface morphology of the nanotubes was imaged by electron microscopy. Ordered and uniformly distributed nanotubes were readily formed on the surface of the titanium foil. The nanotubes had an inner diameter of 20–100 nm, a wall thickness of 10–20 nm, a tube length of 200–500 nm and a closed‐cup, rounded bottom. The as formed nanotubes were weakly crystalline and could be converted to an anatase phase after annealing in air at 400°C for 1 h.