Highly Efficient Ionic Photocurrent Generation through WS₂‐Based 2D Nanofluidic Channels

Abstract

The unique feature of nacre‐like 2D layered materials provides a facile, yet highly efficient way to modulate the transmembrane ion transport from two orthogonal transport directions, either vertical or horizontal. Recently, light‐driven active transport of ionic species in synthetic nanofluidic systems attracts broad research interest. Herein, taking advantage of the photoelectric semiconducting properties of 2D transition metal dichalcogenides, the generation of a directional and greatly enhanced cationic flow through WS2‐based 2D nanofluidic membranes upon asymmetric visible light illumination is reported. Compared with graphene‐based materials, the magnitude of the ionic photocurrent can be enhanced by tens of times, and its photo‐responsiveness can be 2–3.5 times faster. This enhancement is explained by the coexistence of semiconducting and metallic WS2 nanosheets in the hybrid membrane that facilitates the asymmetric diffusion of photoexcited charge carriers on the channel wall, and the high ionic conductance due to the neat membrane structure. To further demonstrate its application, photonic ion switches, photonic ion diodes, and photonic ion transistors as the fundamental elements for light‐controlled nanofluidic circuits are further developed. Exploring new possibilities in the family of liquid processable colloidal 2D materials provides a way toward high‐performance light‐harvesting nanofluidic systems for artificial photosynthesis and sunlight‐driven desalination.

Electric‐Field‐Induced Ionic Sieving at Planar Graphene Oxide Heterojunctions for Miniaturized Water Desalination

“…[ 10 ] Thus, they attract broad research interest and boost various applications in water purification and desalination, chemical sensing and separation, and energy conversion and storage. [ 11–17 ] Pristine and chemically modified GOMs effectively block organic dyes and nanoparticles, [ 18 ] but fail to exclude smaller ions with hydrated diameters less than 9 Å. [ 19 ] Toward sieving of small inorganic salt ions, a number of strategies are proposed to reduce the interlayer spacing down to merely several angstrom, such as capillary compression, [ 20 ] partial reduction, [ 21 ] and cationic control.…”

Optoelectronics Meets Optoionics: Light Storing Carbon Nitrides and Beyond

“…[ 20c,32 ] Likewise, layered systems such as 2D transition metal oxides (e.g., titanates, molybdates, or tungstates) as well as dichalchogenides can provide both an intrinsic ionic component, typically hosted in the interlayer space, and be amenable to PI of electrolyte ions (Figure 4d). [ 33 ] The dimensional flexibility of layered materials along the stacking direction can be an asset, as is the possibility of ions to be present as solvates in the interlayer space, making them more mobile. Further enhancement of ion transport is expected in turbostratically disordered 2D materials with large surface areas, providing a uniquely flat energy landscape and easy access for the diffusing ions (Figure 4e).…”

Tungsten disulfide: synthesis and applications in electrochemical energy storage and conversion

“…On account of the structural similarities to graphene, WS 2 has gained enormous attention recently for a variety of applications such as supercapacitors, secondary batteries, electrocatalysis, photocatalysis, solar cells [10,11,[24][25][26]. WS 2 exhibits typically excellent physical properties such as high charge carrier transport and high wear resistance, which are also similar to those of graphene [27]. In addition, WS 2 put up some superior properties over graphene such as low cost and the tunable band gap with high visible light absorption capability [9].…”