The nanoscale modulation of interlayer space in two-dimensional nanoclay membranes for osmotic energy conversion

The harvest of osmotic energy based on two-dimensional (2D) nanochannel membranes has been attracting wide attentions for addressing the energy issues. Here, we report the nanoscale modulation of interlayer space in 2D nanochannel membranes based on montmorillonite (MMT) for osmotic energy conversion. Cationic surfactants with different alkyl chain lengths are intercalated between MMT nanosheets to regulate the interlayer spacing of 1.74 and 2.49 nm, thus achieving the modulation of ion flux through the nanoclay membranes. A high power density of ∼4.13 W/m2 can be attained in 300-fold concentration gradient. The mechanism of the influence of nanochannel sizes on osmotic energy conversion performance is investigated by experiments and theoretical simulations. Realizing the nanoscale modulation of interlayer space in 2D nanochannels provides new insights for designing nanofluidic membranes toward clean energy harvesting.