An All-in-One Green Energy Solution: Electricity-Freshwater Cogeneration via a Solar-Driven Wood Sponge Evaporator

Solar evaporator takes illumination as the only energy source and obtains clean water and electric energy through interface evaporation, which has broad application prospects in solving environmental energy problems. Here, the composite aerogel network of aramid nanofiber (ANF) and porous carbon nanofiber (PCNF) is impregnated with wood sponge (WS) to form a solar evaporator. The wood substrate, with high water absorption performance, continuously transports water to the evaporation surface, and at the same time, the water clusters are divided to reduce the evaporation enthalpy. WS and ANF provide low thermal conductivity; the black PCNF on the surface provides broadband spectral absorption; the internal PCNF interacts with the wood fiber and fluid to generate streaming potential; and the high surface energy gives it dye adsorption performance. By optimizing the composition of ANF and PCNF, an evaporation rate of 2.931 kg/(m²·h) and a voltage of 138.8 mV were achieved in 3.5 wt % saline water under simulated sunlight (AM 1.5G, 1 sun = 1 kW/m², sample temperature = 25 °C). This work will promote research on the functional modification of biomass solar evaporators, enhance the utilization value of biomass resources, and contribute to solving the global challenge of water pollution and obtaining clean drinking water.