Tailoring anodized TiO2 films for corrosion resistant titanium in alkaline seawater electrolysis

This study investigates the anodizing behavior of commercially pure titanium to develop corrosion resistant and electrically conductive surfaces for alkaline seawater electrolysis. Titanium specimens were anodized at 10-100 V in 1M H 3 PO 4 and the resulting oxide films were characterized by FE-SEM, XPS and electrochemical measurements to evaluate morphology, chemical composition, corrosion behavior and surface conductivity. FE-SEM observations revealed that increasing voltage led to finer surface pores and the formation of uniform and compact TiO 2 layers. At moderate voltages, particularly 50 V, the dense oxide effectively suppressed ion transport and provided excellent corrosion resistance in alkaline chloride environments. Potentiodynamic polarization test in 1 M KOH + 0.5 M NaCl showed a clear decrease in corrosion current density and a positive shift of corrosion potential compared with the untreated Ti surface. XPS analysis confirmed Ti 4+ (Ti 2p) and lattice O 1s peaks along with phosphate residues within the oxide, indicating the formation of a chemically stable amorphous TiO 2 film. At higher voltages, excessive oxide growth cause structural degradation and reduced surface conductivity. The oxide formed at 50 V achieved the best balance between corrosion protection and electrical performance, providing practical insight into optimizing anodizing conditions for titanium components used in alkaline seawater electrolysis systems.