All-natural 2D nanofluidics as high-efficient osmotic energy generator

Abstract

Abstract Two-dimension nanofluidics constructed based on naturally abundant clay are good candidates for harvesting blue osmotic energy between the sea and river from the perspective of commercialization and environmental sustainability. However, clay-based nanofluidic membranes outputting long-term considerable osmotic power remain extremely challenging to achieve due to the lacks of surface charge and mechanical strength. Here, a two-dimension all-natural nanofluidic (2D-NNF) is developed as robust and high-efficient osmotic energy generator based on an interlocking configuration of the stacked montmorillonite nanosheets (from natural clay) and their intercalated cellulose nanofibers (from natural wood). The formed nano-confined interlamellar channels with abundant surface and space negative charges facilitate the selective and fast hopping transport of cations in the 2D-NNF. This contributes to a remarkable osmotic power output of ~ 8.61 W m−2 by mixing artificial seawater and river water, much higher than all reported state-of-the-art 2D nanofluidics. When the 2D nanofluidic membrane is scaled up to 700 cm2, it could also delivery a uniform high-power output of over 8.0 W m−2 at any test sites as well as a long-term stability for 30 days. Such excellent structure uniformity and stability of the large-area membrane are the basic to achieve real-world applications in natural osmotic energy harvesting. Moreover, the 2D-NNF demonstrates superior economic, environment and energy benefits according to a detailed life cycle assessment (LCA), promising a good sustainability for large-scale and highly-efficient osmotic power generation.