Recent Advances in Preparation, Modification, and Application of Free-Standing and Flow-Through Anodic TiO₂ Nanotube...

Free-standing and flow-through anodic TiO₂ nanotube (TNT) membranes are gaining attention due to their unique synergy of properties and morphology, making them valuable in diverse research areas such as (photo)catalysis, energy conversion, environmental purification, sensors, and the biomedical field. The well-organized TiO₂ nanotubes can be efficiently and cost-effectively produced through anodizing, while further utility of this material can be achieved by creating detached and flow-through membranes. This article reviews the latest advancements in the preparation, modification, and application of free-standing and flow-through anodic TiO₂ nanotubes. It offers a comprehensive discussion of the factors influencing the morphology of the oxide and the potential mechanisms behind the electrochemical formation of TiO₂ nanotubes. It examines methods for detachment and opening the bottom ends to prepare free-standing and flow-through TNT membranes and posttreatment strategies tailored to different applications. The article also provides an overview of recent applications of these materials in various fields, including hydrogen production, fuel and solar cells, batteries, pollutant diffusion and degradation, biomedical applications, micromotors, and electrochromic devices.