Ultradense Network Hydrogels for Rapid Solar Vapor Generation

Hydrogel evaporators have enabled evaporation rates beyond thermal limits, attracting wide attention. Macroporous hydrogels with pore sizes larger than 1 μm are generally preferred by researchers because they offer higher evaporation rates than dense hydrogels. However, during long-term application, macroporous hydrogels are prone to pore collapse and are susceptible to factors such as salt crystallization, impurities, and microbial contamination, thus shortening their service life. Herein we propose an interpenetrating network hydrogel (IPNH) with a mesoporous structure (4.2 nm pores) achieving a 1-sun evaporation rate of 4.4 kg m^-2 h^-1, surpassing those of many macroporous hydrogels. This is attributed to its hydrophilic dense network structure, which not only enables efficient water activation and a record-low water evaporation enthalpy (747 J/g at 23 °C) but also balances highly efficient 2 water transport and heat loss. Furthermore, the mesoporous structure imparts IPNH with long-term durability and excellent antifouling capability, making it highly promising for practical applications.