Ion-Engine Hydrogel Based Solar Desalination for Water-electricity Cogeneration with Record-Breaking Milliampere Current

Seawater evaporation-induced electricity generation (SEG) holds significant potential for addressing the global energy and freshwater crises. However, the poor ion selectivity of conventional SEGs leads to an extremely low output current (<10 µA) due to the complex composition of seawater. To overcome this bottleneck, we herein develop a novel ion-engine hydrogel based solar-powered SEG (SSEG), achieving a record-breaking output current of 1.2 mA from seawater under AM1.5G illumination, surpassing previously reported SEGs by 1 to 2 orders of magnitude. Molecular dynamics simulations reveal that the unprecedented current arises from strong synergistic effects of metal-polymer coordination and ion-preferential association within ion-engine hydrogel, which enhances anionic conductivity as well as selectively blocks the Debye shielding effect of cations. As a result, a simply integrated SSEG system operating outdoors can generate power up to 24 mW, demonstrating the feasibility of practical application for powering electronics such as mobile phones, while simultaneously producing freshwater at a high-yield of 2.64 kg m^-2 h^-1. Additionally, the unique ion modulation mechanism boosts the regeneration potential of waste concentrated brine by-products in SSEG systems, enabling the recovery of up to 16.3 W m^-2 of blue energy through reverse electrodialysis, which further improves the sustainability and economic value. This work demonstrates a new paradigm for developing off-grid integrated water-energy cogeneration systems.