Solar evaporation is a process where solar energy is harnessed by photothermal nanomaterials to drive water evaporation at the liquid-vapor interface [1, 2]. The photothermal effect, a representative phenomenon of light-matter interaction, is characterized by a temperature increase in a material due to light absorption [3]. Different materials exhibit varying light-to-heat conversion efficiencies, depending on their electronic or bandgap structures’ responses to electromagnetic radiation [4]. The phase change process relies on the absorption of solar radiation by the water surface, which increases the kinetic energy of water and solute molecules, causing their transition from a liquid to a vapor state or solid crystal [5–7]. This section will provide a concise overview of the basic physics underlying the solar evaporation process.