Turing-type nanochannel membranes with extrinsic ion transport pathways for high-efficiency osmotic energy harvesting

Abstract

Two-dimensional (2D) nanofluidic channels with confined transport pathways and abundant surface functional groups have been extensively investigated to achieve osmotic energy harvesting. However, solely relying on intrinsic interlayer channels results in insufficient permeability, thereby limiting the output power densities, which poses a significant challenge to the widespread application of these materials. Herein, we present a nanoconfined sacrificial template (NST) strategy to create a crafted channel structure, termed as Turing-type nanochannels, within the membrane. Extrinsic interlaced channels are formed between the lamellae using copper hydroxide nanowires as sacrificial templates. These Turing-type nanochannels significantly increase transport pathways and functional areas, resulting in a 23% enhancement in ionic current while maintaining a cation selectivity of 0.91. The output power density of the Turing-type nanochannel membrane increases from 3.9 to 5.9 W m−2 and remains stable for at least 120 hours. This membrane exhibits enhanced applicability in real saltwater environments across China, achieving output power densities of 7.7 W m−2 in natural seawater and 9.8 W m−2 in salt-lake brine. This work demonstrates the promising potential of the Turing-channel design for nanoconfined ionic transport in the energy conversion field. High permselectivity of nanofluidics remains a challenge in osmotic energy conversion. Here, authors construct two dimensional nanofluidics with Turing-type nanochannels, which provide extrinsic pathways to improve both ion selectivity and flux, thereby achieving efficient osmotic energy harvesting.