Abstract The solar‐driven interfacial evaporation (SIE) technology shows great prospects in seawater desalination and sewage treatment, but it is unable to obtain highly efficient and high‐quality clean nontoxic water at low cost. Here, a novel biodegradable hydrogel‐based solar evaporator (BBH‐L) with a bionic coral structure taking Chinese ink as the solar absorber was developed. This evaporator consists of chitosan/polyvinyl alcohol hydrogel and a loofah substrate. The average evaporation rate and efficiency of BBH‐L reach 4.37 kg/(m2·h) and 98.2%, respectively, under one sun illumination (1 kW/m2), which are attributed to its excellent thermal localization and water transporting abilities. Meanwhile, high salt resistance enables BBH‐L to achieve efficient desalination and purification of other unconventional water. Heavy metal ions in seawater can be effectively removed by chelation and forming hydrogen bonds in hydrogels. This study is anticipated to provide new possibilities to enhance evaporation performance and reduce the costs of water treatment systems.
