Synergistic photothermal-osmotic energy harvesting via hierarchical Ti4O7/cellulose membrane for solar-powered freshwater-electricity cogeneration

Osmotic energy is a promising clean and sustainable resource for osmotic power generation. However, scaling up reverse electrodialysis technology for osmotic energy harvesting is constrained by limited output power density, primarily due to the dependence of passive ion transport on the concentration gradient. Interfacial solar evaporators yield freshwater and highly concentrated brine. But inevitable heat losses reduce the solar energy utilization efficiency. This study was to construct a multilayer mesh composite membrane with tunable pore sizes via Ti 4 O 7 ceramic fibers and nanocellulose fibers, which adaptable to varying salt concentration environments. Solar radiation can be introduced for seawater desalination coupled with the osmotic energy conversion process to achieve more efficient solar energy utilization. The nanoconfined domains within the multilayer composite membrane enable an efficient interfacial solar water evaporation at a rate of 5.97 kg m −2  h −1 . The effective utilization of heat conduction energy losses elevates the osmosis power generation density to 7.60 W m −2 , which is increased by 198 % compared to conventional device models. This provides a novel design approach for applying ceramic fibers in osmosis power generation and for developing efficient, integrated freshwater-electricity cogeneration systems.