Nano Dot‐Mediated Cation Transport Through Two‐Dimensional Nanofluidic Membranes for High Osmotic Energy Generation

Two‐dimensional (2D) nanofluidic membranes have shown great potential for precise ion transport control in osmotic energy conversion. However, relying solely on their intrinsic surface charge and size‐sieving effects is inadequate to achieve efficient selective ion transport and high energy conversion performance. Herein, we demonstrate a nano dot‐infused graphene oxide (GO) nanofluidic membrane to enhance ion permselectivity and unveil how the nano dot mediates selective cation transport. The incorporation of graphitic carbon nitride nano dots (CNNDs) introduces extra negative charges that enhance the ion selectivity of the 2D nanochannels, while the coordination interactions between Na + ions and nitrogen‐containing groups on CNNDs lower the energy barrier for Na + migration, facilitating highly efficient ion diffusion. When applied to osmotic energy generation, the GO/CNNDs membranes exhibit a remarkable cation selectivity coefficient of up to 0.95 and achieve an exceptional power density of 18.4 W m −2 under a 50‐fold NaCl concentration gradient, a 5.4‐fold enhancement compared to that of GO membranes. Notably, the membrane also exhibits excellent stable performance in practical complex environments and organic solvents. This work highlights the critical role of nano dots in accelerating cation transport and demonstrates the practical potential of GO/CNNDs membranes for efficient and durable osmotic energy harvesting.