Robust Holey Graphene Oxide/Cellulose Nanofiber Composites for Sustainable and Efficient Osmotic Energy Conversion

Nanofluidic membranes utilize selective ion transport to capture osmotic energy from salinity gradients, efficiently converting it to electrical energy. However, traditional nanofluidic material synthesis still encounters challenges, including low charge density, high ion transport energy barriers, and limited current output. Here, we present a composite membrane consisting of hole-enriched graphene oxide (HGO) and cellulose nanofibers (CNF), engineered to enhance ion transport and energy conversion. HGO facilitates direct ion transfer through the nanopore within lamellar layers, effectively reducing the transmission distance and lowering the energy barrier for ion movement, thus enabling faster ion transfer between layers. CNF, on the other hand, offers robust mechanical strength and numerous active groups, imparting high ion selectivity to the nanoporous membrane. An osmotic energy generator utilizing the HGO/CNF membrane achieved a peak power density of 1.25 W m–2. Notably, the cationic transference number and energy conversion efficiency peaked at 0.84 and 23.64%, respectively, under a 500-fold concentration gradient. Additionally, the HGO/CNF composite membrane exhibits a robust tensile strength of 78.51 MPa, underscoring its excellent mechanical properties. The above results suggest that this highly ion-selective and energy-efficient composite membrane presents a promising avenue for advancing osmotic energy research.