A Novel Thin Film Composite Membrane for Osmotic Energy Generation

A novel thin film composite (TFC) membrane was developed to simultaneously achieve high energy density and mechanical robustness for osmotic energy generation (OEG). The composite membrane is composed of a poly(vinyl alcohol) (PVA) aerogel substrate and a thin sulfonated poly(ether ether ketone)/graphene (SPEEK/G) top layer. The PVA support offers excellent mechanical stability, flexibility, and high water permeability, and the mixed matrix skin layer amplifies the differential diffusion rates of cations and anions across the TFC membrane. As a result, the TFC membrane manages to achieve a high power density of ca. 5.89 W m^-2 under a salinity gradient of 50 (0.5 M|0.01 M, NaCl). Furthermore, the energy generation device can maintain the high power output for 4 days or under 300 P pressure, indicating excellent long-term stability and mechanical durability. The work thus provides a new membrane technology to prepare high-performance materials for osmotic energy harvesting application.