TiO₂-fiber-enabled phase-change aerogel evaporator for sustained solar-driven interfacial evaporation

Solar-driven interfacial evaporation (SDIE) is promising for desalination and wastewater purification, yet its practical application is limited by fluctuating solar input and insufficient thermal buffering. Herein, we report a phase-change-assisted evaporator, denoted as TCOEF, comprising a TiO₂ fiber/chitosan aerogel loaded with 1-octadecene (ODE) and covered by a PAN/C fibrous photothermal membrane. The incorporation of heat-treated TiO₂ fibers maintained a more open and accessible porous morphology, facilitating ODE infiltration and increasing its loading capacity. ODE acted as a latent-heat reservoir to store solar heat under strong irradiation and release it under reduced-light or dark conditions, while the PAN/C membrane enabled broadband solar absorption and capillary water transport. TCOEF exhibited an average solar absorptance of 94% over 200-2500 nm and achieved an evaporation rate of 1.72 kg m^-2 h^-1 under 1 sun. It also maintained effective evaporation in saline, acidic, alkaline and dye-containing water, with major ion concentrations in the condensate below relevant drinking-water limits. This work provides an integrated strategy for sustained SDIE under fluctuating irradiation.