Abstract
Harnessing osmotic energy from salinity gradients presents a compelling avenue for sustainable, pollution-free blue energy conversion. Despite the promise, developing cost-effective, easily manufactured, and highly ion-selective membranes for efficient osmotic power generation is a significant challenge. Here, we reveal that natural kelp membranes with nanoporous structures exhibit excellent ionic selectivity for capturing osmotic energy. Benefiting from the three-dimensional robust interlocking nanochannels configuration and a wealth of negatively charged hydroxyl groups, the all-natural kelp membranes enable selective and fast hopping transport of cations resulting in a high-power density of 3.1 W m−2 and a current density of 178 A m−2 under a 50-fold salinity gradient. This discovery not only highlights the substantial potential of kelp in advancing osmotic energy harvesting but also paves the way for the development of large-scale, cost-effective ionic osmotic generators.