This effect was discovered in 1995 by the Research Institute of Toto Ltd. for titanium dioxide irradiated by sunlight.
Under light irradiation, water dropped onto titanium dioxide forms no contact angle (almost 0 degrees).
For example, it can defog glass, and it can also enable oil spots to be swept away easily with water.
Such materials are already commercialized as door mirrors for cars, coatings for buildings, self-cleaning glass, etc.
[citation needed] Several mechanisms of this superhydrophilicity have been proposed by researchers.