Nanofluidics in two-dimensional layered materials: inspirations from nature

Abstract

With the advance of chemistry, materials science, and nanotechnology, significant progress has been achieved in the design and application of synthetic nanofluidic devices and materials, mimicking the gating, rectifying, and adaptive functions of biological ion channels. Fundamental physics and chemistry behind these novel transport phenomena on the nanoscale have been explored in depth on single-pore platforms. However, toward real-world applications, one major challenge is to extrapolate these single-pore devices into macroscopic materials. Recently, inspired partially by the layered microstructure of nacre, the material design and large-scale integration of artificial nanofluidic devices have stepped into a completely new stage, termed 2D nanofluidics. Unique advantages of the 2D layered materials have been found, such as facile and scalable fabrication, high flux, efficient chemical modification, tunable channel size, etc. These features enable wide applications in, for example, biomimetic ion transport manipulation, molecular sieving, water treatment, and nanofluidic energy conversion and storage. This review highlights the recent progress, current challenges, and future perspectives in this emerging research field of "2D nanofluidics", with emphasis on the thought of bio-inspiration.

Nanofluidic Ion Transport and Energy Conversion through Ultrathin Free‐Standing Polymeric Carbon Nitride Membranes

“…In salinity gradient energy conversion for example, [4] thedimensions of the channels are close to the Debye screening length, and the surface charge of the channels can drastically alter the ionic behaviors of the nanofluids.T his effectively repels the counterions,a llowing only the target ions to transport through. [7] Forinstance,Huang et al realized an ion-transport nanofluid based on reconstructed layered graphene oxide paper. [5] Tw o-dimensional materials, [6] for example graphene and graphene oxide (GO), would be the ultimate step for such membranes,a nd nanosheets with similar 2D structures have been assembled into nano-channeled membranes,ahot topic of scientific research.…”

Confining Free Radicals in Close Vicinity to Contaminants Enables Ultrafast Fenton‐like Processes in the Interspacing of MoS2 Membranes

“…However, the gallery height of bulk MoS 2 is too narrow (ca. [10] Thus an anofluidic AOPp latform with aM oS 2 lamellar membrane as af ree radical activator was here constructed for highly effective water purification. [7] Achieving high exposure of the active surfaces and edges is the key issue for efficient activation of PMS.T wo-dimensional (2D) materials with their considerable specific surface area should show ahigh exposure of surfaces and edges.…”

“…In comparison with conventional AOPc onfigurations,t he diffusion distance of aqueous organic molecules in nano-sized interspacings should be significantly decreased. [10] Thus an anofluidic AOPp latform with aM oS 2 lamellar membrane as af ree radical activator was here constructed for highly effective water purification. [10] Thus an anofluidic AOPp latform with aM oS 2 lamellar membrane as af ree radical activator was here constructed for highly effective water purification.…”

“…Assembling 2D nanosheets into alamellar membrane is an alternative approach, [9] where the active sites on the 2D surface can be well-preserved. [10] Thus an anofluidic AOPp latform with aM oS 2 lamellar membrane as af ree radical activator was here constructed for highly effective water purification. Moreover,Fickslaw indicates that the steep concentration gradient (perpendicular to the flow direction, Scheme 1) in the nano-sized interspacing has the potential to propel both small organic molecules and PMS from the center to the boundaries.T he rapid mass transportation primarily strengthens the activation efficiency between PMS and the activators,r esulting in ah igh concentration of ROS.A tt he same time,a s-activated radicals in close vicinity to contaminants have more chances to attack to these molecules (see the Supporting Information, Figure S1).…”

Confined Self‐Assembly in Two‐Dimensional Interlayer Space: Monolayered Mesoporous Carbon Nanosheets with In‐Plane Orderly Arranged Mesopores and a Highly Graphitized Framework

“…[1][2][3] Among these materials,carbon materials with 2D or pseudo-2D morphologies are of particular interest for applications such as catalysis,water/gas purification, or energy conversion/ storage,o wing to their intrinsic advantages of large specific surface area (SSA), excellent electrical conductivity,chemical inertness,a nd low cost. Monolayer-ordered mesoporous carbon nanosheets (OMCNS) were prepared through confinement assembly of resol and F127 in the interlayer of montmorillonite (MONT).…”