Ammonia responsive surface wettability switched on indium hydroxide films with micro- and nanostructures

Switchable surface wettability that can be tuned reversibly between superhydrophobicity and superhydrophilicity has been successfully realized on indium hydroxide films with micro- and nanostructures. The films are superhydrophobic in the air with a water contact angle of 150.4 ± 0.9° while they turn superhydrophilic with a water contact angle of 0° after storage in an ammonia atmosphere, which means an ammonia responsive surface wettablity switch. The novel surface wettability is ascribed to the multiple surface structures and surface free energy conversion of the films. This kind of smart surface wettability is promising in developing new types of ammonia detectors simply by virtue of the surface wettability conversion.