Constructing Continuous Interlayer Hydrogen‐Bond Network in Nanofluidic Clay Membranes for Fast Cation Conduction and Anti‐Swelling Osmotic Energy Generators

ABSTRACT Two‐dimensional clay nanofluidic membranes hold great promise for harvesting sustainable osmotic energy, yet their practical application is constrained by two core challenges. (1) The inherently tortuous and inefficient ion transport pathways within stacked nanosheet structures limit cation flux, and (2) the severe swelling of interlayer nanochannels in aqueous environments impairs ion selectivity and long‐term stability. To simultaneously tackle these challenges, we construct a continuous hydrogen‐bond network within the interlayer of a lamellar membrane (CHM) via a sequential crosslinking strategy. This engineered network serves a dual function: (1) establishing low‐energy barrier pathways to facilitate cation transport while (2) acting as a dynamic yet robust crosslinked matrix to anchor clay nanosheets for suppressing interlayer expansion. Experimental and theoretical results confirm that the negatively charged surface, in synergy with the hydrogen‐bond network, enables selective and rapid cation transport. The ionic conductivity of in‐plane transport reaches as high as 22 S m −1 in 1 m electrolyte. When employed for osmotic energy harvesting from artificial seawater and river water, the CHM delivers an impressive high‐power density of 22.7 W m −2 and maintains stable power output for over 30 days. Furthermore, an integrated osmotic power generator successfully drives multiple electronic devices, demonstrating its real‐world applicability.