High-throughput fabrication of TiO2 nanotube arrays by 4-electrode bipolar electrochemistry

Abstract

Size tunable TiO2 nanotube arrays (TNAs) are promising materials in biomedical applications and photocatalysis. Rapidly screening an optimal dimension of TNAs under various application conditions is challengeable, for which a high-throughput TNA platform is significantly important. Herein, 4-electrode bipolar electrochemistry (4EBPE) was proposed to implement a controllable fabrication of gradient TNAs. Theoretical calculations showed that the shift of cathode/anode boundary is the principal cause of uncontrollable overpotential distribution over the bipolar electrode (BPE) and undesirable gradient of the TNAs for normal bipolar anodization. The 4EBPE could improve the anodization process of gradient TNAs through an extra imposed overpotential on the BPE. The dimension of TNAs fabricated by 4EBPE is linearly dependent on the position over the electrode, and the gradient ranges of TNAs can be freely controlled through the electrochemical parameters. The gradient TNAs fabricated by the 4EBPE are promising platforms for high-throughput research.