Light-Induced Heat Driving Active Ion Transport Based on 2D MXene Nanofluids for Enhancing Osmotic Energy Conversion

Osmotic energy from the ocean, also called blue energy, serves as a clean, renewable, and vast energy source for the energy demands of the world. Reverse electrodialysis-based blue energy harvesting via ion-selective membranes, by the regulation and manipulation of directional ion transport, has been greatly developed recently. In particular, light has been employed to enhance directional ion transport for energy conversion through an increase in photo-induced surface charge. Here, the authors demonstrate a novel nanofluidic regulation strategy based on the phenomenon of light-induced heat-driven active ion transport through the lamellar MXene membrane. Due to the great light-induced heat effect, a temperature gradient appears as soon as illumination is applied to an off-center position, inducing an actively temperature gradient-driven ionic species transport. By employing this phenomenon, the authors conducted light-induced heat-enhanced osmotic energy conversion and doubled the osmotic energy conversion power density. This study has extended the scope of light-enhanced osmotic energy conversion and could further bring other photothermal materials into this field. Furthermore, the proposed system provides a new avenue of light-controlled ionic transport for ion gathering, desalination, and energy conversion applications.