Photo-induced Wettability Control on TiO2 Surface

Abstract

Introducing surface roughness using a photoelectrochemical etching technique successfully controlled the reversible wettability on a TiO2 surface. The hydrophilic conversion property is enhanced on the etched surface irradiated with UV light. This is plausible considering Wenzel's equation, that is, the hydrophilic property is enhanced by increasing the surface roughness. Moreover, the reversible switching between the hydrophobicity (> 120 degree) and the high hydrophilicity (0 degree) is achieved by alternating between UV light irradiation and dark storage. The hydrophobicity of TiO2 surface is understandable considering Cassie's equation.