Engineering Multiscale Heterostructure as Ionic Diode and Light-Driven Ion Pump for Osmotic-Solar Energy Harvesting

As blue energy, osmotic power holds tremendous potential for electricity generation via membranebased reverse electrodialysis. However, current processes suffer from low energy output mainly due to inadequate transmembrane ion transport and a polarization phenomenon. Inspired by plant growth and photosynthesis, we proposed a robust heterogeneous membrane that enabled ionic -diode rectified and light -enhanced ion transport for efficient osmotic -solar energy harvesting. The membrane was rationally constructed by in -situ growth of polyaniline (PANI) onto a sulfonated matrix, creating a multiscale heterostructure that enabled the coexistence of a Janus -like architecture and semiconductor heterojunction. Benefiting from multi -asymmetries of geometry, charge, and chemistry, the membrane delivered a high unidirectional ion flow and suppressed polarization, generating an exceptional osmotic power density of up to 12.6 W m -2 at a 50 -fold salinity gradient. Light -driven ion pumping was achieved by the synergistic photothermal and photoelectric effect of PANI heterojunction. Under light irradiation, temperature gradient and transmembrane potential were triggered simultaneously, accelerating ion movement, thereby elevating the energy conversion output. This work pioneers the development of highperformance power generators capable of harnessing energy from diverse salty sources coupled with a solar resource.