Multi-interface engineering of solar evaporation devices via scalable, synchronous thermal shrinkage and foaming

Recent years have witnessed continuing advances in solar evaporation technologies to achieve strong synergy among sufficient water supply, efficient light absorption, and favorable heat localization. Still, challenges remain in the fabrication of solar evaporation devices with synergistic performance in a scalable fashion. Herein, we develop a scalable fabrication process involving multi-scale and multi-interface engineering to achieve high-performance and large-area solar evaporation devices. At nanoscale, light-absorbing carbon nanotubes (CNTs) are complexed with hydrophilic cellulose nanofibers (CNFs) to form the nanocomposite inks of CNT-CNF (c-CNT) with tunable viscosity for doctor blading on ethanol-diffused polystyrene (E-PS) films. Through one-step thermal treatment, device shrinkage and substrate foaming are triggered at multi-interfaces to synchronously induce (1) the creation of microscale crumpled c-CNT textures with dual-improved water supply and light absorption and (2) the generation of mesoscale pores in PS substrates with dual-suppressed thermal conduction and radiation. Contributed by the synergistic designs, the solar evaporation device demonstrates a high evaporation rate of 1.41 kg m−2 h−1 and a conversion efficiency of 95.8% at an extremely low loading of photothermal materials (0.25 mg cm−2). A large-area solar evaporation panel is realized to highlight the practical consideration toward more impactful solar evaporation exploitation.