Forward osmosis membrane doped with water-based zirconium fumarate MOFs to enhance dye pollutant removal and membrane antifouling performance.

Metal-organic frameworks (MOFs) can be applied to enhance the property of forward osmosis membranes. However, organic solvents can easily remain in organic synthetic metal-organic frame materials and cause membrane fouling and a decrease in membrane permeability. In this study, water-based Zr-fumarate MOFs were synthesized and doped into the membrane active layer by interfacial polymerization to provide a water-based MOF-doped thin-film composite membrane (TFC membrane). It was found that doping the water-based MOFs effectively improved membrane hydrophilicity, and nanowater passages were introduced in the active layer to improve permeability. The water flux of the water-based MOF-doped TFC membranes was increased by 21% over that of the original membrane, and the selectivity performance of the membrane was improved while keeping the salt rejection basically unchanged. Additionally, the water-based MOF-doped TFC membrane showed good removal efficiency (Rd > 94%) and strong antipollution performance in the treatment of dye pollutants.

2D multifunctional SiAs2/GeAs2van der Waals heterostructure.

The structural and electronic properties of two-dimensional (2D) SiAs2/GeAs2van der Waals heterostructure (vdWH) and its applications are investigated by combing first-principles calculations and Silvaco Atlas simulations. The stable SiAs2/GeAs2vdWH exhibits an indirect bandgap of 0.99 eV in type II band alignment for light detection and energy harvesting. The vdWH can exhibit a direct bandgap up to 0.66 eV by applying an appropriate electric field (Eext). Due to theEextinduced charge redistribution, its band alignment can be transformed from type II to type I for light-emitting. Further simulation shows that the band alignment of SiAs2/GeAs2vdWH can be tuned back and forth between type II and type I by gate voltage in a single field-effect transistor for multiple functional applications. These results may be useful for applications of the SiAs2/GeAs2heterostructure in future electronic and optoelectronic devices.

BiOCl/group-IV Xene bilayer heterojunctions: stability and electronic and photocatalytic properties.

Vertical van der Waals heterojunctions (HJs) composed of a photocatalytic star material BiOCl monolayer and group-IV Xene monolayer (silicene, germanene etc.) were studied by using first-principles calculations. Formation energy analysis and molecular dynamics simulation show that the BiOCl/Xene bilayer HJs can exist stably up to room temperature. Owing to evident charge redistribution and accumulation occurring between the bilayers, electron-hole puddles form and charge carrier transfer and separation occur in the HJs, which are beneficial to the improvement of photocatalytic performance. The HJ energy bands maintain the Dirac cones with almost linear dispersion curves, suggesting low effective mass and high mobility of carriers, and can be effectively tuned by strain. Our results show that the BiOCl/Xene bilayer HJs with high separation efficiency and high mobility of carriers and strain-adjustable bandgaps provide varieties in the functionalities of 2D van der Waals HJs and show great potentials in photocatalytic applications.