Harnessing Multiple Donnan Effects for Simultaneous Salt-Resistant Solar Desalination and Dual-Mode Power Generation.

Abstract

Coupling solar desalination with multi-mechanism power generation offers a promising dual solution to water and energy crises, yet salt crystallization poses a major obstacle. Here, we present an integrated system featuring as multiple Donnan effects for salt-resistant solar desalination and dual-mode power generation. Leveraging the mechanisms of hydrogen bond differentials and Fe³⁺-tannic acid crosslinking, a ─SO₃ ^--functionalized porous sponge evaporator (PSE-SO₃ ^-) was fabricated. Enabled by the Donnan effect of ─SO₃ ^- groups, the evaporator simultaneously resists salt accumulation and boosts hydrovoltaic power generation, thereby achieving a peak seawater evaporation rate of 4.19 kg m^-2 h^-1 under one-sun irradiation while maintaining a salt-free surface. Simultaneously, PSE2-SO₃ ^- generated electricity via the hydrovoltaic effect, delivering outstanding power densities of 5.76/4.34 mW m^-2 under one sun/dark conditions. Molecular dynamics simulations and in situ Raman spectroscopy confirmed Cl^- interception and elucidated the H⁺-water interaction mechanism for power generation. Furthermore, integrating reverse electrodialysis based on the Donnan effect as an auxiliary strategy enhanced salt resistance of PSE2-SO₃ ^- and delivered an osmotic power output of 0.804 W m^-2. Scale-up of the self-designed integrated system to an outdoor environment revealed synergistic performance outcomes, thereby establishing a pioneering demonstration platform for the efficient cogeneration of clean water and energy from seawater.