Advancing osmotic power generation using bioinspired MXene-based membrane via maze breaking

The osmotic energy generated by the salinity gradient between seawater and river water is a potential blue energy that can be harnessed to alleviate the current energy crisis but without causing environmental pollution. Two dimensional (2D) MXene nano sheets can be horizontally assembled into laminar membranes to create nanochannels enabling the ionic selective transport and thus to capture the osmotic energy. However, the ions have to transport through the maze-like tortuous laminar channels sourced from the interspaces between two neighboring nanosheets, which lead to super-high transport resistance and low power density, hindering their wide applications. Enlightened by the water and mineral ions transport in trees, here, a bioinspired MXene-based membrane with aligned and ordered vertical channels is developed for efficient osmotic power generation from salinity gradient. The peak power density of the electrical devices composed of such maze-breaking membranes could be achieved up to 372 W m−2, which is at least one order of magnitude higher than conventionally horizontal membranes reported in the literature. The high-power generation efficiency was attributed to the shortened ionic transport path (by breaking the maze). Moreover, the membrane possesses a high antifouling performance as well as long-term stability, possibly due to the strong combination of MXene and GO via the hydrogen bonds and cross-linking in preparation. This work reports a new and high-performance MXene-based membrane not only for osmotic energy conversion but also for other practical separations.