Unlocking osmotic energy harvesting potential in challenging real-world hypersaline environments through vermiculite-based hetero-nanochannels

J Wang and Z Cui and SZ Li and ZY Song and ML He and DX Huang and Y Feng and YZ Liu and K Zhou and XD Wang and L Wang, NATURE COMMUNICATIONS, 15, 608 (2024).

DOI: 10.1038/s41467-023-44434-1

Nanochannel membranes have demonstrated remarkable potential for osmotic energy harvesting; however, their efficiency in practical high-salinity systems is hindered by reduced ion selectivity. Here, we propose a dual- separation transport strategy by constructing a two-dimensional (2D) vermiculite (VMT)-based heterogeneous nanofluidic system via an eco- friendly and scalable method. The cations are initially separated and enriched in micropores of substrates during the transmembrane diffusion, followed by secondary precise sieving in ultra-thin VMT laminates with high ion flux. Resultantly, our nanofluidic system demonstrates efficient osmotic energy harvesting performance, especially in hypersaline environment. Notably, we achieve a maximum power density of 33.76 W m-2, a 6.2-fold improvement with a ten-fold increase in salinity gradient, surpassing state-of-the-art nanochannel membranes under challenging conditions. Additionally, we confirm practical hypersaline osmotic power generation using various natural salt-lake brines, achieving a power density of 25.9 W m-2. This work triggers the hopes for practical blue energy conversion using advanced nanoarchitecture. Harvesting osmotic energy in real world high-salinity solutions poses great challenges, authors propose nanofluidic membranes with a dual separation mechanism based on vermiculite nanosheets with an isomorphic substitution structure, showing excellent energy conversion in hypersaline environments.

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