Spatially decoupled tri-domain phase-change evaporators for all-weather antibacterial solar desalination

Tri-domain architecture perfectly decouples water paths from hydrophobic PCM. • Hydrogel interface ensures rapid capillary flow and a 4.5 kg·m −2 ·h −1 vapor rate. • Confined n -eicosane actively buffers thermal energy for all-weather evaporation. • In-situ grown ZnO nanoparticles deliver ∼99% broad-spectrum antibacterial rates. Interfacial solar evaporation is a promising strategy for sustainable desalination, yet its practical deployment is restricted by solar intermittency, phase-change material (PCM) hydrophobicity, and biological fouling. To address these challenges, a bioinspired, spatially decoupled tri-domain phase-change evaporator was developed. A delignified and carbonized wood scaffold was employed to confine an n -eicosane PCM core with a phase-change enthalpy of 168.2 J/g, while its aligned microchannels supported photothermal conversion and directional transport. A polydopamine/sodium alginate hydrogel skin was further integrated to reconstruct a highly wettable interface, decreasing the water contact angle from 96.9° to 19.2° and functionally separating the interfacial water-supply pathway from the internal hydrophobic thermal-storage domain. In addition, in situ grown ZnO nanoparticles provided antibacterial functionality, enabling approximately 99% inactivation of both E. coli and S. aureus in the final hydrogel-coated evaporator. The optimized PH@ZH-PCM exhibited thermal conductivities of 0.43 and 0.46 W m −1  K −1 in the dry and wet states, respectively, and achieved a peak 5-min-interval apparent evaporation rate of approximately 2.8 kg m −2  h −1 under 1 sun irradiation. Outdoor day-to-night and illumination–dark experiments further demonstrated its adaptability to fluctuating solar irradiation and post-illumination thermal-buffering capability. Moreover, the evaporator maintained continuous evaporation in NaCl solutions with concentrations of up to 20 wt%, exhibited reversible surface salt deposition and cleaning recovery, and produced freshwater with a Zn concentration of only 0.0080 mg L −1 . This spatially decoupled architecture provides a promising platform for efficient outdoor day-to-night solar desalination under variable environmental conditions. Download: Download high-res image (166KB) Download: Download full-size image