Optimizing Nanofluidic Energy Harvesting in Synthetic Clay-based Membranes by Annealing Treatment

Nanofluidic energy harvesting from salinity gradients is studied in 2D nanomaterials-based membranes with promising performance as high ion selectivity and fast ion transport. In addition, moving forward to scalable, feasible systems requires environmentally friendly materials to make the application sustainable. Clay-based membranes are attractive for being environmentally friendly, non-hazardous, and easy to manipulate materials. However, achieving underwater stability for clay-based membranes remains challenging. In this work, the synthetic clay Laponite is used to prepare clay-based membranes with high stability and excellent performance for osmotic energy harvesting. The Laponite membranes (Lap-membranes) are stabilized by low-temperature annealing treatment to effectively reduce the interlayer space, achieving a continuous operation under salinity gradients. Furthermore, the Lap-membranes conserve integrity while soaking in water for more than one month. The output power density improves from approximate to 4.97 W m-2 on the pristine membrane to approximate to 9.89 W m-2 in the membrane treated 12 h at 300 degrees C from a 30-fold concentration gradient. Especially, It is found that the presence of interlayer water to be favorable for ion transport. Different mechanisms are proposed in the Lap-membranes involved for efficient ion selectivity and the states found with varying annealing temperatures. This work demonstrates the potential application of Laponite based nanomaterials for nanofluidic energy harvesting. The 2D-nanofluidic device based on Laponite clay demonstrates excellent performance for osmotic energy harvesting after annealing treatment. The membrane treated at 300 degrees C displays superior selectivity for Na+ ions and high ion flux, leading to the maximum power density of 9.89 W m-2. This establishes the possibility of designing environmentally friendly Laponite-based nanofluidic devices of facile fabrication and low cost. image