▎ 摘　　要

NOVELTY - Multi-layered membrane (600) comprises a top layer (900), a bottom layer (700), and a spacer layer (800), where the spacer layer is interposed between the top layer and the bottom layer, the top layer, the bottom layer and the spacer layer are each independently composed of at least one selective layers, each selective layer (1000) comprising a two dimensional material, the spacer layer comprises at least one channel for receiving a fluid, the bottom layer comprises a hole with an area of 1 mu m2 to 1 mm2; and the hole is capable of being in fluid communication with the at least one channel of the spacer layer. USE - The multi-layered membrane is useful: for separating many ions or molecules in a fluid stream; and in device for osmotic power generation (all claimed). ADVANTAGE - The multi-layered membrane: has enhanced mobility of cations or anions than the respective counter ion, which shows counter-ion rejection which does not affect the water permeation properties of the multi layered membrane; shows enhanced ionic mobility to enhance ionic conductivity of the solution regardless of the pH of the ionic or electrolyte solution; ensures enhanced diffusivity of cations and reduced flow of anions in a cation selective multi-layered membrane, or enhanced diffusivity of anions and reduced flow of cations in an anion selective multi-layered membrane; allows thinner top layer to be used without any unwanted bending effects; is deposited on a support or embedded in a matrix to serve as active multi-layered membrane when it is incorporated into another membrane or system; is 30 times cheaper; generates 1000 times more power for the same surface area compared to conventional membranes to make it cost effective and energy efficient for commercial applications. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) synthesizing a top layer of a multi-layered membrane; (2) separating many ions or molecules in a fluid stream, where the method uses saline; and (3) device. DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the multi-layered membrane. Multi-layered membrane (600) Bottom layer (700) Spacer layer (800) Top layer (900) Selective layer (1000)