Facile electrochemical synthesis of anatase nano-architectured titanium dioxide films with reversible superhydrophilic behavior

In the present work we report a facile and readily-scalable electrochemical anodization technique for preparation of superhydrophilic TiO₂ films having reversible wettability properties. The electrochemically anodized Titanium (Ti) foils manifest nanoscale topographical features, interconnected nanowebs and nanofibrils, that enhance both surface roughness and light absorption. After 5 min of UV illumination a water contact angle (WCA) of 4.8° is measured for a 5 μL deionized water droplet, while after 5 min of whitelight illumination the WCA is 3.2°. Moreover, under UV illumination the superhydrophilic Ti foils exhibit self-cleaning properties. Key factors contributing to the superhydrophilic character include surface topology, and surface chemical reactions.