Aligned regenerated cellulose-based nanofluidic fibers with ultrahigh ionic conductivity and underwater stability for osmotic energy harvesting

The growing interest in biomass-based nanofluids has revealed flaws in large-scale manufacturing, customizable aligned nanostructures, and the weak interaction of structural components, resulting in low ionic conductivity, unsatisfactory long-term reliability underwater, and insufficient energy conversion efficiency. Herein, we present a bottom-up strategy integrating cellulose dissolution, orientation, regeneration, and densification to construct regenerated cellulose-based nanofluidic fibers (RCNFs) comprising a high weight content of acidified carbon nanotubes (40 %), aligned nanochannels (3-4 nm), and negatively charged surfaces (-3.05 mC m(-2)). Benefited from the synergistic alignment and spatial confinement of CNTs by the cross-linked cellulose network, the RCNFs realized a high underwater strength (29 MPa), unprecedentedly high ionic conductivity (0.07 S cm(-1)) at low salt concentrations (<0.001 M), and high long-term output power density (2.57 W m(-2) over 43 days) in an artificial river water-seawater system. In a proof-of-concept experiment, customizable RCNF-based devices connected in series powered a calculator and LED lights at a 50-fold concentration gradient. This work can promote the application of regenerated cellulose in high-performance osmotic energy conversion systems.

Automated summary

A bottom-up strategy integrating cellulose dissolution, orientation, regeneration, and densification was used to construct regenerated cellulose-based nanofluidic fibers (RCNFs) with high weight content of acidified carbon nanotubes, aligned nanochannels, and negatively charged surfaces. The RCNFs exhibited high underwater strength, unprecedentedly high ionic conductivity, and high long-term output power density. They were successfully used to power a calculator and LED lights in a proof-of-concept experiment.