Light-enhanced osmotic energy generation with an aramid nanofiber membrane

Osmotic energy generation with reverse electrodialysis through membranes provides a worldwide free energy resource. Photo-driven proton transport in photosynthesis supplies basal energy for plants and living organisms on the planet. Here, we utilized aramid nanofiber (ANF) semiconductor-based membranes to enable light-driven proton transport for osmotic energy generation. Under unilateral illumination, the light-driven proton transport system converted light energy into electrical energy and showed wavelength- and intensity-dependent transmembrane potentials and currents. Interestingly, the synergistic effects of simultaneous illumination and pressure provided a five-fold increase in the voltage and a three-fold increase in the current relative to pressure alone. Density functional theory calculations and spectroscopic measurements demonstrated that the ANF and photoinduced electrons enabled proton transport during illumination and generated a transmembrane potential and current. The light-driven proton transport system supports the development of devices with flexible and stable ANF membranes.