Giant Gateable Osmotic Power Generation from a Goldilocks Two- Dimensional Polymer

BR Cheng and Y Zhong and YQ Qiu and S Vaikuntanathan and J Park, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 145, 5261-5269 (2023).

DOI: 10.1021/jacs.2c12853

Generating electricity from a salinity gradient, known as osmotic power, provides a sustainable energy source, but it requires precise nanoscale control of membranes for maximum performance. Here, we report an ultrathin membrane, where molecule-specific short-range interactions enable giant gateable osmotic power with a record high power density (2 kW/m2 for 1 M parallel to 1 mM KCl). Our membranes are charge-neutral two-dimensional polymers synthesized from molecular building blocks and operate in a Goldilocks regime that simultaneously maintains high ionic conductivity and permselectivity. Molecular dynamics simulations quantitatively confirm that the functionalized nanopores are small enough for high selectivity through shortrange ion-membrane interactions and large enough for fast cross membrane transport. The short-range mechanism further enables reversible gateable operation, as demonstrated by polarity switching of osmotic power with additional gating ions.

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