<p>The global scarcity of freshwater resources has become increasingly critical in recent years, highlighting the urgent need to develop efficient and energy-saving solar evaporative materials for seawater desalination and effluent purification. In this study, pulp fiber was employed as a raw material without any chemical pretreatment to prepare an aerogel evaporator through a one-step freeze-casting process. This approach offers process simplicity, cost-effectiveness, facile microstructure regulation, and excellent evaporation performance. The aerogel possesses a multidimensional layered structure with interconnected macropores, as well as excellent mechanical stability and water transport ability, which is attributed to the abundant hydroxyl groups. The incorporation of carbon nanotubes (CNTs) significantly improves photothermal absorption ability and conversion efficiency. The evaporator delivers a remarkable evaporation rate of 1.91&#xa0;kg·m⁻²·h⁻¹ and a high energy conversion efficiency of 92% under one-sun irradiation with simulated seawater. Furthermore, driven by capillary forces and ion migration, the aerogel generates a voltage of 532.45&#xa0;mV, a current of 240.64 μA, and an output power of 24.12&#xa0;μW·cm⁻², demonstrating promising capability for water-electricity cogeneration. Additionally, the aerogel evaporator exhibits remarkable salt resistance, cycling stability, and outdoor adaptability, as well as effective purification of high-salinity seawater and organic dye-contaminated effluent. This work offers a new alternative for the high-value utilization of biomass resources and structural optimization of solar interfacial evaporator.</p> Graphical abstract <p></p>