More than 3.6 billion people face water scarcity, and conventional desalination consumes large amounts of energy. Solar-driven interfacial evaporation (SDIE) offers a sustainable option, but performance is hindered by wasted heat, fragile coatings, and poor stability, long considered an "impossible triangle" of challenges in the field.
Researchers at Nanchang University have now broken this bottleneck with a bio-inspired approach. Drawing on the flexibility of crocodile skin and the vascular efficiency of leaves, the team engineered multifunctional cracked metal-phenolic network (MC-MPN) coatings on sponge substrates. The controlled crack structures create ultrathin water layers that concentrate heat at the evaporation interface, achieving a record evaporation rate of 3.2 kg m-2 h-1.
The coating's metal ions, such as Fe3+, provide strong photocatalytic activity, enabling simultaneous removal of organic dyes and antibiotics during evaporation. Laboratory tests showed pollutant degradation exceeding 99 percent, while the crack networks also act as stress buffers, protecting the coating from damage under repeated compression. Even after 1000 mechanical cycles, evaporation and purification performance remained stable.
In field trials, the team deployed an outdoor solar-powered treatment system using seawater from the South China Sea. Over seven days, the device maintained a steady evaporation rate between 2.8 and 3.3 kg m-2 h-1 and consistently produced clear water with ion concentrations far below World Health Organization drinking water standards.
By combining efficiency, durability, and multifunctionality, this cracked coating design overcomes a central limitation of SDIE and points to practical solar-powered desalination and water remediation solutions. The approach offers promising applications for addressing global freshwater shortages.
