Mechanically intensified and stabilized MXene membranes via the combination of graphene oxide for highly efficient osmotic power production

Abstract

Harnessing the osmotic energy from the salt concentration gradient between sea water and river water in nature represents as a promising sustainable power generation pathway that does not generate waste and CO2 emission. However, the current membranes with two-dimensional nano-channels generally have low mechanical strength, poor stability, and low transmission power efficiency, which result into low current and power density (≤1 W m−2) performance. Herein, we use MXene combined with GO (MXene/GO) to synthesize a composite membrane as a high-performance nanofluid permeability generator. The addition of 2D flexible GO membrane enhances the mechanical strength to achieve the required robustness of the composite membrane for practical application. By using river and sea water in the permeability generator, the power density for the MXene/GO composite membrane with 6 wt% GO can reach 3.7 W m−2 at room temperature (298 K). The influences of different GO ratio, pH, temperature, and membrane thickness on power density are also evaluated. At 343 K and pH = 7, the power density of 420 nm-thick MXene/GO composite membrane can achieve 7.88 W m−2, which is higher than most of the state-of-the-art membranes, highlighting the possibility of osmotic power generation. This work reports a new promising membrane for the practical application of osmotic energy conversion.