No abstract

Nanofiltration membrane-based molecular separation has become an indispensable technology for fine sieving processes. However, the difficulty in regulating the separation performance restricts the applicability of these nanofiltration membranes in different separation systems. Herein, we will show that the separation performance of Ti 3 C 2 T x −MXene lamellar nanofiltration membranes on certain dye molecules can be modulated by employing external electrostatic fields. Specifically, for cationic dyes, the negative voltage applied to Ti 3 C 2 T x lamellar nanofiltration membranes can improve their sieving abilities on dyes but reduce their water flux at the same time. On the contrary, a positive electric field will cause a decline in the retention capacities but improve the water flux of the membranes. Interestingly, when using anionic dye molecules as solute models, the filtration performance of the Ti 3 C 2 T x membranes exhibits completely opposite variations to that of filtering cationic dyes, whether the applied electric field is negative or positive. The regulation mechanisms for the filtration performance of Ti 3 C 2 T x membranes have been discussed, which are probably ascribed to the changes in the electrostatic interactions between dyes and Ti 3 C 2 T x induced by the external electric field. Our findings indicate that the filtration performance of MXene lamellar membranes on both cationic and anionic dyes can be modulated by applying an external electric field, opening up enormous opportunities to use such electrified nanofiltration membranes in the field of membrane-based molecular separations.

NiS is deposited on the surface of hexagonal ZnIn2S4 via a hydrothermal method and the as‐obtained NiS/ZnIn2S4 nanocomposite shows superior activity for photocatalytic dehydrogenative coupling of amines to produce imines, with simultaneous generation of hydrogen under visible light. The superior performance over NiS/ZnIn2S4 for photocatalytic dehydrogenative coupling of benzylamine to produce N‐benzylidenebenzylamine can not only be ascribed to NiS, which acts as a cocatalyst to promote the charge transfer and hydrogen evolution, but also attributed to its strong adsorption toward benzylamine and its relatively weak adsorption toward the product, which is also proved by density functional theory calculations. This study not only provides an efficient, green, and cost‐effective strategy to produce imines, but also demonstrates that the adsorption of the photocatalyst toward the reactants and the products is an important issue that should be considered in a photocatalytic reaction.

UiO-66(Zr), a UV-responsive Zr-based metal–organic framework (MOF) material, is found to be highly active and chemoselective for the visible-light-initiated acceptor-less dehydrogenation of alcohols to coproduce vicinal diols and H2. The formation of a colored surface alkoxide complex between alcohols and UiO-66(Zr) enables the UV-responsive UiO-66(Zr) to be active under visible light, while the formation of a hydrogen bond between alcohols and μ3-OH in UiO-66(Zr) is responsible for its high selectivity to vicinal diols. The elucidation of the involved mechanism will provide some guidance for the controllable syntheses of vicinal diols and aldehydes, a very important reaction in the chemical industry, via the visible-light-initiated acceptor-less dehydrogenation of alcohols.

The utilization of solar light to trigger organic syntheses for the production of value-added chemicals has attracted increasing recent research attention. The integration of plasmonic Au NPs (NPs = nanoparticles) with MOFs would provide a new way for the development of highly efficient photocatalytic systems. In this manuscript, a bottle-around-ship strategy was adopted for the successful synthesis of a core−shell structured Au pvp @MIL-100(Fe) (PVP = polyvinylpyrrolidone) nanocomposite in room temperature. The as-obtained core−shell structured Au pvp @MIL-100(Fe) show improved photocatalytic performance for benzyl alcohol oxidation under visible light, because of the migration of the surface plasmon resonance (SPR) excited hot electrons from plasmonic Au NPs to MIL-100(Fe), resulting in the production of more active O 2•− radicals. The removal of the capping agent PVP from Au pvp @MIL-100(Fe) significantly enhanced the photocatalytic performance, because of an improved charge transfer from plasmonic Au NPs to . This study demonstrates an efficient strategy of fabricating superior photocatalytic systems by a rational coupling of plasmonic Au NPs and photocatalytic active MOFs into a core−shell structured nanocomposite.