A Novel Two-step Electrochemical Approach for the Complete Filling of Cu2O into TiO2 Nanotube Arrays as An Anti-fouling Titanium Surface

摘要

Titanium has great potential for application in the marine engineering due to its corrosion resistance, low density, and chemical stability, but titanium is also prone to suffer from marine biofouling, thus limiting its further development. Completely filling the interior of TiO 2 nanotube arrays, generated by electrochemical anodizing on the titanium surface, with Cu 2O, a biocide widely used in anti -fouling coatings, seems to be a promising approach for developing a novel biocidal anti -fouling titanium surface. The tubular structure of TiO 2 nanotube arrays not only loads a large amount of Cu 2O but also slows down its release rate in the marine environment. Herein, we devised an innovative and simple two -step electrochemical approach to completely fill TiO2 nanotube arrays with Cu2O. This approach involves a precise cathodic polarization to selectively enhance the bottom conductivity of TiO 2 nanotube arrays, followed by an optimized pulsed deposition to fill Cu 2O. EIS and Mott -Schottky plots results showed that after cathodic polarization of TiO 2 nanotube arrays at −1.7 V (vs.SCE) for 60 s in 1 mol/L (NH 4)2SO4 aqueous solution, the charge transfer resistance Rbl of the inner barrier layer decreased by two orders of magnitude, while the charge transfer resistance Rnt of the outer nanotube layer remained unchanged, and the carrier density increased by four orders of magnitude. The selective enhancement of the bottom conductivity of TiO2 nanotube arrays resulted in the nucleation of Cu 2O at the bottom and growth along the bottom-to-top direction during pulse deposition. Laboratory anti-adhesion experiments demonstrated that the completely filling of Cu 2O into TiO 2 nanotube arrays showed remarkable effectiveness against marine bacteria ((99.51 ± 0.17) % for Bacillus sp.), marine diatoms ((99.60 ± 0.13) % for P. tricornutum), and barnacles ((100 ± 0) %). Furthermore, the completely filling of Cu2O into TiO2 nanotube arrays also exhibited a durable resistance to P. tricornutum adhesion for up to 49 days ((99.52 ± 0.15) %) in the laboratory and prevented barnacle settlement for 20 days in the marine environment. This preparation method of the complete filling of Cu 2O into TiO2 nanotube arrays offers a promising and reliable strategy to address the marine biofouling problem of titanium.