The role of mild and hard anodization regimes of iron oxide nanotubes in the photoelectrochemical performance

•Fe2O3 nanotubes (NTs) prepared by electrochemical anodization for solar water splitting applications.•Two regimes of anodization, Mild and Hard, observed in NTs geometrical features (Dp, Dint, W, L) and anodization curves (j(t) and Q(t))•Relation between charge curves Q(t), nanotubes length (L), and introducing porosity (P) as a parametric, established to estimate L by an adapted Classical Faraday’s Law.•Estimated L from adapted Classical Faradaýs Law in excellent agreement with the experimental data from SEM.