Mechanically strong MXene/Kevlar nanofiber composite membranes as high-performance nanofluidic osmotic power generators

Abstract

Two-dimensional nanofluidic channels are emerging candidates for capturing osmotic energy from salinity gradients. However, present two-dimensional nanofluidic architectures are generally constructed by simple stacking of pristine nanosheets with insufficient charge densities, and exhibit low-efficiency transport dynamics, consequently resulting in undesirable power densities (<1 W m −2 ). Here we demonstrate MXene/Kevlar nanofiber composite membranes as high-performance nanofluidic osmotic power generators. By mixing river water and sea water, the power density can achieve a value of approximately 4.1 W m −2 , outperforming the state-of-art membranes to the best of our knowledge. Experiments and theoretical calculations reveal that the correlation between surface charge of MXene and space charge brought by nanofibers plays a key role in modulating ion diffusion and can synergistically contribute to such a considerable energy conversion performance. This work highlights the promise in the coupling of surface charge and space charge in nanoconfinement for energy conversion driven by chemical potential gradients.

Vertically Transported Graphene Oxide for High‐Performance Osmotic Energy Conversion

“…The obtained output power density of V-GOMs can achieve an unprecedented high value of 10.6 W m -2 , which is the highest reported record among all existing materials used to harvest osmotic energy, including PCTE 36 , UFSCNM 17 , PSS/MOF 18 , IDM 13 , PPy 12 , PET-BCP 19 , MKNCM 21 , H-GOMs 20 , CMI 13 and FKS 13 (Fig. 2d).…”

“…2b). Reference electrodes were applied in electrical measurement to eliminate the contribution of redox potential generated by the unequal potential change at the electrode-solution interface 10,21 .…”

“…Towards practical application, the NREDS were widely studied in a variety of porous materials, including polymeric membranes 11,12 , inorganic carbon materials 13,14 , silicon-based materials 15 , aluminum oxide (AAO) template 16 , compound materials [17][18][19] and stacked 2D materials 20 . Up to now, the highest record by mixing seawater and river water is 4.1 W m -2 obtained in MXene/Kevlar nanofiber composite membranes 21 . Although it largely outperforms commercial ion exchange membranes by nearly an order of magnitude, the power density is still below the commercialization benchmark of 5.0 W m -2 in the seawater/fresh water systems 22,23 .…”

Oppositely Charged Ti3C2Tx MXene Membranes with 2D Nanofluidic Channels for Osmotic Energy Harvesting

“…5 W m −2 ) . Previous studies have demonstrated that the maximum extractable power density is found when R L = R M , where R M is the internal resistance of the RED system, which mainly derived from the membrane . The measured internal resistance of the MXM pairs is the lowest value ever reported 2D membranes, which is crucial for developing large‐scale RED osmotic energy harvesting .…”

Fabrication, Applications, and Prospects of Aramid Nanofiber

“…Although ANF shows impressive insulation properties, its superior mechanical properties, high aspect ratio, good film‐forming property, and excellent thermal stability make it a perfect alternative to be integrated with conductive nanomaterials to construct flexible, robust, and conductive ANF‐based electronics that have promising applications in nanofluidic osmotic power generators, [ 102 ] composite electrodes, [ 103,104 ] and electromagnetic interference (EMI) shielding. [ 17 ] For example, current 2D nanofluidic architectures show low‐efficiency transport dynamics and undesirable power densities due to the insufficient charge densities of the components.…”