A strategy of fast reversible wettability changes of WO3 surfaces between superhydrophilicity and superhydrophobicity

As-prepared WO3 nanostructure films on alumina or tungsten substrates by a facile hydrothermal method exhibit a superhydrophilic property. An effective strategy is proposed to control the wettability of WO3 films in a reversible manner between superhydrophilicity and superhydrophobicity with a rapid response. By controlling the process of adsorption/desorption of n-dodecanethiol associated with the light-induced plating Ag nano-grains on WO3 nanostructures, it only takes about 25 min to fulfill the wettability change from superhydrophilicity to superhydrophobicity, and only 30 s to finish the reversed change. Moreover, the contact angles of WO3 surface can be tuned by controlling the etching time of superhydrophobic WO3 surfaces in a solution of nitric acid containing 5 mM sodium dodecyl benzene sulfonate. Electrowetting process is successfully demonstrated to trap a water drop onto the superhydrophobic WO3 surfaces. Considering WO3 is one of typical electrochromic materials, researches on the effect of coupling between electrowetting and electrochromic properties would be more promising.

Graphical abstractSmart surface of WO3 nanostructure films can change its wettability from superhydrophilicity to superhydrophobicity within 25 min, and 30 s for the reverse process.Figure optionsDownload full-size imageDownload high-quality image (16 K)Download as PowerPoint slideResearch highlights► Reversible wettability of WO3 between superhydrophilicity and superhydrophobicity. ► Taking 25 min from superhydrophilicity to superhydrophobicity, and 30 s for reverse. ► Trap a water drop onto the superhydrophobic surfaces by electrowetting. ► Light-induced plating Ag nano-grains on WO3 nanostructures.