Freestanding Ultrathin Precisely Structured Hierarchical Porous Carbon Blackbody Film for Efficient Solar Interfacial Evaporation

Solar‐energy‐powered interfacial evaporation is the most meaningful strategy for energy utilization, water desalination, and mineral purification. It can achieve high efficiency, low‐density energy, and sustainable harvest and utilization. However, the microstructure and surface/interface design still lead to a balance between solar–thermal conversion, water conduction, and thermal management, which also determines the efficiency of photothermal interfacial evaporation. Here, a free‐standing, ultrathin carbon film with a tunable nanopore diameter is prepared and used as a blackbody layer for solar photothermal evaporation. By 3D reconstruction methods, the effect of pore structure on interfacial evaporation is systematically studied. Hierarchical porous carbon film with an average pore size of about 300 nm exhibits outstanding photothermal evaporation performance, reaching up to 1.96 kg m −2 h −1 with excellent stability. Ultra‐hydrophobic, optically enhanced absorption graphene array is constructed on the carbon film surface through femtosecond laser nanoprocessing, further increasing the evaporation rate to 2.12 kg m −2 h −1 (1 sun) and 5.55 kg m −2 h −1 (3 suns).