**3.1 Triphase interfaces**

In the liquid phase, air pockets are stuck with the rough topological surface of the superhydrophobic substrate, forming a triphasic solid–liquid-air interface. For photocatalytic reactions, this triphasic contact line usually serves as an active area for interfacial reactions and provides a vital clue to surface behavior. The oxygen supply from the air reacts with photogenerated electrons from the surface of the photocatalyst, producing oxidative reactive oxygen species (ROS) such as superoxide radicals (O2 •−) and hydroxide radicals (OH• ) and resulting in the degradation of organic pollutants (**Figure 4**). Especially, during organic pollutant degradation, the carbon bonds breaks the on the superhydrophobic surface and can show long-term stability. Practically, a superhydrophobic with long-term stability catalyst is required.
