Multilevel nanochannels for high-efficient ion selectivity and salinity gradient power generation

Salinity gradient energy is widely present in river estuaries and has a huge reserve. Salinity gradient energy can be directly transformed into electrical energy via reverse electrodialysis, which has recently garnered widespread attention due to its simple and pollution -free utilization process. The emergence of two-dimensional (2D) materials has brought new opportunities because regular nanochannels and abundant functional groups enable their output power density to -2 exceed the commercial standard of 5 W m . However, the membrane testing area for salinity gradient power generation is generally 3 x 10 4 mu m 2 , and the power decreases considerably with increasing testing area. In this paper, a 2D -2D multilevel layered structure of graphene oxide and molybdenum disulfide (GO-MoS 2 ) is prepared using a simple vacuum filtration method. This structure enables the ion -selective membrane to maintain an ordered structure even over a large area, achieving high ion selectivity and transport and eventually reaching high output power density. Meanwhile, the prepared 2D -2D structure effectively controls swelling in 2D material membranes and offers abundant surface holes and multilevel interlayer spacing, thereby realizing fast ion -selective transport. The osmotic power generation test results over a large area (3.14 mm 2 , 100 times larger than those of other studies) showed that the osmotic voltage and current of the GO-MoS 2 membranes perform satisfactorily, with a power density of 0.57 W m -2 at a 100 -fold gradient, which is 92.7% higher than those of the original GO membranes. The 2D -2D multilevel layered structure provides a new perspective for fabricating large -area and simple -to -prepare high-performance ion -selective membranes and guidance for the industrial application of 2D materials in the fields of salinity gradient power generation, seawater desalination, gas separation, biomedicine, and so on.