Self-twisting three-dimensional core-shell nanofiber yarns with high salt resistance for solar-driven interfacial evaporators in water-electrical cogeneration

Abstract

Solar interfacial evaporation (SIE) technology holds promise for mitigate water scarcity and electricity energy shortages, yet salt crystallization at the evaporation interface remains a critical barrier to stable water-electrical cogeneration. Herein, an evaporator featuring a three-dimensional vertical array structure composed of self-twisting core-shell nanofiber yarns was designed. Upon external stimulation, hydrophilic Poly(p-dioxanone) (PPDO) nanofiber yarns spontaneous twist to form vertically aligned and mechanically robust cores for rapid capillary water transport. The graphene (GE)-doped PPDO shell enables broadband solar absorption and effective vapor escape, while the core-shell structure achieves dynamic salt equilibrium, preventing crystallization even after operating for 8 h in 25 % NaCl solution. Molecular level indicates that the interaction between PPDO and water weakens hydrogen bonds, reducing the evaporation enthalpy, achieving an evaporation rate of 3.7 kg·m⁻²·h⁻¹ under 1 Sun. The evaporator delivers 0.62 V and 0.065 mA under 2 Sun in 10 % NaCl solution, alongside dye removal, oil-water separation, and antibacterial activity. The self-twisting three-dimensional core-shell nanofiber yarn evaporator provides a scalable path to high performance solar driven clean water and sustainable energy systems.