Optimization of activated carbon fiber felt for solar interfacial evaporation

To achieve climate goals and advance sustainable development worldwide, solar energy plays a crucial role. Solar interfacial evaporation (SIE) has gained attention as an energy-efficient alternative to conventional volumetric distillation for seawater desalination, offering enhanced solar-to-vapor conversion by concentrating photothermal energy at the water-air interface. However, the scalability of SIE systems is often limited by the high cost and complex manufacturing of most solar evaporators. In this work, we demonstrate a low-cost activated carbon fiber felt (ACFF) with high solar absorption as a high-performance solar evaporator for desalination. Under simulated solar irradiation (0.5–1.5 sun) and ambient conditions (∼25 °C, ∼50% RH), the flat ACFF evaporator achieved evaporation rates of 0.73–1.84 kg m⁻² h⁻¹, respectively, with solar-vapor conversion efficiency up to 81.3%. When tested with saline feedwater (1–10 wt% NaCl), it sustained stable performance with rates of 1.26–1.29 kg m⁻² h⁻¹, demonstrating strong salt resistance. In outdoor environments with low solar irradiance (averaging 332 W m⁻²), the system produced a daily water yield of 1.18 kg m⁻², confirming its real-world applicability. To enhance solar energy utilization and elevate water yield, we systematically evaluated key factors affecting evaporation efficiency–including evaporator size, porosity, thickness, structure, and condenser design, using Multiphysics simulations. This study not only validates ACFF as a scalable and accessible material for SIE, but also provides a simulation-guided optimization framework to support better utilization of solar energy and wider adoption of SIE technology, further advancing global water-energy sustainability. © 2026 Elsevier B.V.