Progress on free-standing and flow-through TiO2 nanotube membranes

TiO2 nanotube arrays are important nano-materials in a variety of technological areas, such as photovoltaic, catalysis, nano-template, sensors, etc. Free-standing/flow-through TiO2 nanotube membranes with high aspect ratio and good uniformity exhibit even more functionalities in energy and environmental applications. This report presents a review of all pioneered technologies to prepare the free-standing/flow-through TiO2 nanotube membrane as well as the mechanism behind the detachment process. The developments of structural optimization techniques of the detached membrane are described from the electrochemistry point of view. The application status for solar cells, water splitting, hydrogen sensors, supercapacitors, CO2 reduction and photocatalysis are also highlighted.