Ion Conveying Electron Enabling Electrodeless Osmotic Energy Harvesting

ABSTRACT Osmotic energy, a renewable energy source characterized by its cleanliness, environmental friendliness, and abundant resources, has attracted considerable research interest. Electrodes convert ionic currents to electronic currents via Faraday reactions, while their high cost, consumption rate, and maintenance requirements significantly hinder economic viability. Therefore, we propose the concept of ion‐conveying electrons and design an electron‐conducting ion‐exchange membrane (ECIEM) for electrodeless osmotic energy harvesting. In this system, ions traversing the ECIEM directly convert ionic current to electronic current by capturing and directionally dragging electrons within the conductor via Coulombic forces. Specifically, ions convey electrons across the membrane to the dilute solution side like a conveyor belt, thereby realizing the direct conversion of ionic currents to electronic currents. These electrons then enter the external circuit via a current collector and return to the concentrated solution side, enabling the electrodeless process to continuously generate power. Using a chitosan‐alginate biopolymer membrane incorporating doped graphene/carbon nanotubes and featuring a gradient charge distribution design, we achieved an electrodeless output power density of 24.2 W/m 2 . The performance surpasses that of traditional redox‐based systems (5.31 W/m 2 ) by 4.6 times, primarily by circumventing electrode side reactions and solution resistances. Tests with multi‐module series connections and using natural seawater and river water demonstrate the scalability and practical utility of the approach. The demonstrated electrodeless strategy achieves both cost savings and performance enhancement, offering a versatile route toward developing efficient, low‐cost osmotic energy harvesting systems.