Preparation of lotus-root-typed TiO2 nanotubes by NH4F/KF based electrolyte and its efficient photocathodic protection for 304 stainless steel

A highly ordered lotus-root-typed TiO2 nanotube array (TNTAs) was prepared by two-step electrochemical anodization in a novel NH4F/KF-based electrolyte. The effects of different morphologies of TiO2 nanotubes on the photoelectrochemical properties of TNTAs were studied. The photoelectrochemical properties of TNTAs were evaluated by measuring the photocurrent density-time curve. The photocathodic protection performance of TNTAs on 304 stainless steel was evaluated by measuring open circuit potential and Tafel curve. The results showed that the TNTAs with lotus-root-type porous structures prepared at 20 V had the optimal photoelectric chemical properties and photocathodic protection properties. Under simulated sunlight, the maximum photocurrent density can reach 306.7 μA·cm−2, and the lowest open circuit potential can reach -0.987 V (vs Ag/AgCl).