Spatially Decoupled Photothermal Conversion, Evaporation and Condensation Interfaces for Efficient Water Harvesting in Solar Distiller

ABSTRACT Solar‐driven interfacial evaporation is a promising alternative for sustainable freshwater production from seawater desalination. While substantial improvement has been achieved in boosting evaporation rate, mutual interference between incident light and generated vapor/condensed droplets in conventional closed chambers results in a stark mismatch between evaporation performance and liquid freshwater output. Herein, we demonstrate an efficient solar distiller featuring spatially decoupled photothermal conversion and evaporation‐condensation interfaces. Solar heat generated by the top carbon black‐coated copper plate solar absorber transfers via heat pipes to a capillary‐fed polyacrylonitrile (PAN) nanofiber evaporator. Unlike traditional photothermal evaporators, this spatially separated structure avoids salt deposition and surface fouling on the light‐absorbing layer, while substantially elevating evaporation rates. Integrated hydrophobic aluminum fins enable rapid latent heat dissipation for condensation, realizing an optimal water collection rate of 1.71 kg m −2 h −1 under 1 sun. Isolating the photothermal layer eliminates vapor‐induced light loss and improves structural stability. Outdoor prototypes with an average daily water collection rate of 1.46 kg m −2 h −1 , together with their modular design, validate the promising scalability for solar desalination. This spatially decoupled design offers a new paradigm for high‐efficiency solar seawater desalination and on‐site distributed clean‐water production.