A Gd3+-doped blue TiO2 nanotube array anode for efficient electrocatalytic degradation of iohexol

• A Gd 3+ -doped blue TiO 2 nanotube array anode (Gd-BTNA) is successfully fabricated. • Gd 3+ doping can introduce O V and increases the specific surface area of the anode. • Gd-BTNA has an enhanced electrocatalytic performance for the degradation of IOH. • DFT calculation and LC-MS are employed to confirm the degradation path of IOH. A Gd 3+ -doped blue TiO 2 nanotube array anode (Gd-BTNA) was successfully fabricated by the processes of anodization, Gd doping and cathodization. The electrocatalytic activity of a blue TiO 2 nanotube array anode (BTNA) can be improved by Gd doping, which introduced oxygen vacancies into the material and increases the specific surface area of the anode. Gd-BTNA is used to eliminate iohexol (IOH) in water, and the optimal operating parameters for electrochemical degradation of IOH are a current density of 15 mA cm −2 , initial solution pH of 6.5 and initial IOH concentration of 10 ppm. Coexisting components in wastewater have adverse effects on the treatment process, including Cl – , HCO 3 – , NH 4 + and humic acid. Under the optimal conditions, complete degradation of IOH was obtained within 18 min and more than 52.1% total organic carbon (TOC) was removed after 60 min of reaction time, which outperforms the BTNA and several commercial electrodes. The excellent efficiencies in electrochemical degradation of iohexol show that Gd-BTNA was a promising anode to treat iodinated contrast media contaminants.