Tunable Interlayer‐Spacing Graphene Oxide Membrane: Efficient Osmotic Energy Conversion Toward Metal Recovery

Abstract

2D material membranes show promise in osmotic energy (OE) conversion and separation technologies. However, low ion flux and swelling limit their applications. Herein, a polydopamine‐crosslinked graphene oxide membrane (PDA@GO) with tunable interlayer spacing is developed to address these challenges. PDA expands the interlayer spacing, optimizes Debye length matching, and reduces ion transport barriers. Compared to pristine GO membranes, PDA@GO membranes achieve a 369% higher ion flux and a power density of 10.06 W m−2 under a 500‐fold NaCl gradient. Besides, PDA@GO membranes show excellent anti‐swelling stability in aqueous solution up to 60 days. Furthermore, integrating green chemistry principles, PDA@GO enables dual energy‐resource utilization, successfully recovering copper ions from wastewater via OE. This work highlights the potential of 2D membrane systems in high‐efficiency energy conversion and sustainable wastewater treatment.