Amorphous TiO₂ Bridges Stabilized WS₂ Membranes with Excellent Filtration Stability and Photocatalysis-Driving Self-Cleaning Ability

Abstract

Two-dimensional (2D) membranes as a new type of water filtration membrane have shown great potential in water separation and purification. However, their long-term stability under cross-flow conditions and their antifouling property are two main concerns for practical separation and purification processes. In this work, a strategy of nanoparticle bridges based on amorphous TiO2 is developed to link adjacent WS2 nanosheets on a WS2 membrane surface, leading to a strong membrane surface with excellent stability during 204 h of continuous cross-flow filtration. Moreover, the amorphous TiO2 bridges also form a TiO2/WS2 heterojunction on the WS2 membrane surface, exhibiting an impressive photocatalysis-driving self-cleaning property by pollutant photodegradation. And the flux recovery ratio (FRR) exceeds 95% after three cycles of separation experiments. The excellent long-term stability and photocatalysis-driving self-cleaning property of the WS2/TiO2 membrane provide a new approach to construct robust 2D membranes.

WS2-TiO2 Heterostructure Catalyst for Boosting the Polysulfide Adsorption–Conversion in Lithium–Sulfur Batteries

“…The energy gap between Ti 2p 1/2 and Ti 2p 3/2 is close to 5.8 eV in both WS 2 -TiO 2 and TiO 2 , which is the oxidation state of Ti 4+ . Moreover, Ti 2p 1/2 and Ti 2p 3/2 in WS 2 -TiO 2 are both higher than those in TiO 2 (about 0.3 eV), which is due to the Ti-O-W linkage on the WS 2 -TiO 2 surface by transformation of electrons to WS 2 , − which also demonstrates the formation of heterostructures.…”

“…There are four obvious peaks before and after adsorption in Figure c. Before adsorption of Li 2 S 6 , W 4f 5/2 (34.2 eV) and W 4f 7/2 (32 eV) correspond to W 4+ , and W 4f 5/2 (37.6 eV) and W 4f 7/2 (35.4 eV) correspond to the high state W 6+ , which is jointly attributed to the oxidation of WS 2 on the surface of WS 2 -TiO 2 and the formation of a Ti-O-W bond. , After adsorption of Li 2 S 6 , W 4f 5/2 and W 4f 7/2 peaks move toward the direction of lower binding energy, which proves the existence of electron transfer between Li 2 S 6 and WS 2 Figure d shows the change of S 2p binding energy before and after adsorption of Li 2 S 6 .…”

Functionalized 2D membranes for separations at the 1-nm scale

“…Apart from active fouling resistance and release, 2D membranes can be functionalized with photocatalysts to obtain selfcleaning properties; that is, the organic contaminants accumulated on the membrane surface can be degraded when exposed to UV or visible light. A variety of photocatalysts, including titanium dioxide (TiO 2 ), 169,170 graphitic carbon nitride (g-C 3 N 4 ), 171 Fe-based nanomaterials, 172,173 and various heterojunction composites, 174,175 have been integrated into 2D membranes to obtain self-cleaning performance. For instance, the intercalation of g-C 3 N 4 @TiO 2 heterojunctions into lamellar GO membranes enables sunlight-driven self-cleaning properties for the recovery of water flux in practical water/oil separation.…”

Cation-Intercalated Clay-Based Two-Dimensional Membranes for Effective Desalination and Molecule Sieving

“…The recently emerging two-dimensional (2D) lamellar membranes based on 2D nanomaterials have attracted a lot of interest due to their outstanding properties and great potential for water treatment. − Considerable progresses of 2D membranes reveal a new perspective on advanced membranes in the application of desalination, molecule separation, and ion sieving. − 2D membranes are constructed by stacking 2D nanosheets to form a layered structure, and let different ions or molecules selectively permeate through 2D membrane by means of size sieving and interaction between 2D membrane and specific ions or molecules. , Nair and co-workers have reported that GO membranes could block all molecules or ions with hydrated radii larger than 4.5 Å by immersing in water . 2D membranes based on MXene nanosheets effectively excluded molecules with diameters larger than 2.5 nm .…”