Gamma-phase cesium lead tri-bromide perovskite nanocrystals (γ-CsPbBr3 NCs) possess potentially photo-catalytic degradation ability and long-term stability. However, their serious aggregation issue decreases their active surface area, and the recombination of photo-generated hole–electron pairs weakens their photo-catalytic property. Furthermore, these NCs can be easily absorbed on the surface of dyes [e.g., methylene blue (MB)] or dissolved in the dye solution during the photo-catalytic degradation process, thus reducing the amount of γ-CsPbBr3 NCs and their photo-catalytic degradation ability. Besides, the residual γ-CsPbBr3 NCs in the photo-catalytic degradation products also present the toxicity issue (containing Pb) and are hazardous to the ecological environment and human health. In the present study, we fabricated γ-CsPbBr3 NCs/polymethyl methacrylate electrospun nanofibrous membranes (γ-CsPbBr3 NCs/PMMA ENMs) by using electrospinning technology to solve the above problems. It is found that the synthesized γ-CsPbBr3 NCs/PMMA ENMs show a large surface area and the abundant functional groups on their surfaces, which are benefit for forming multiple kinds of chemical bonding effect between γ-CsPbBr3 NCs and PMMA ENMs. In addition, γ-CsPbBr3 NCs could disperse homogeneously in or on the surface of PMMA ENMs. These abundant chemical bonds and homogeneous distributions of γ-CsPbBr3 NCs on the surface of PMMA ENMs can significantly decrease the recombination of photo-generated hole–electron pairs and toxicity issue of γ-CsPbBr3 NCs during the photo-catalytic degradation process. Exhilaratingly, γ-CsPbBr3 NCs/PMMA ENMs could maintain a superior photo-catalytic degradation ability toward various dyes and reveal a high photo-catalytic degradation efficiency of 99.18% in 60 min for MB.
Electrospun peapod-like TiO2@GO@C nanofiber membranes enhance their photocatalytic properties for the improved crystallinity of TiO2 and carrier transport, and simultaneously improve their mechanical properties.
Excitons are quasi-particles composed of electron–hole
pairs
through Coulomb interaction. Due to the atomic-thin thickness, they
are tightly bound in monolayer transition metal dichalcogenides (TMDs)
and dominate their optical properties. The capability to manipulate
the excitonic behavior can significantly influence the photon emission
or carrier transport performance of TMD-based devices. However, on-demand
and region-selective manipulation of the excitonic states in a reversible
manner remains challenging so far. Herein, harnessing the coordinated
effect of femtosecond-laser-driven atomic defect generation, interfacial
electron transfer, and surface molecular desorption/adsorption, we
develop an all-optical approach to manipulate the charge states of
excitons in monolayer molybdenum disulfide (MoS2). Through
steering the laser beam, we demonstrate reconfigurable optical encoding
of the excitonic charge states (between neutral and negative states)
on a single MoS2 flake. Our technique can be extended to
other TMDs materials, which will guide the design of all-optical and
reconfigurable TMD-based optoelectronic and nanophotonic devices.
For the first time the enzymatic esterification of starch in deep eutectic solvent (DES) was reported using DES of choline chloride (ChCl)‐ethylene glycol (EG) as reaction solvent/medium, Novozyme 435 as catalyst, and PEG 400 as phase transfer agent to synthesize starch decanoate, starch laurate, and starch palmitate. The product samples of esterified starches were characterized by FTIR, 1H NMR, GPC, SEM, XRD, and DSC tests. The results showed that, the degrees of substitution were in the range of 0.07‐0.19 and the addition of PEG 400 was helpful to increase the DS. The optimal esterification temperature for DS was 338 K in the range studied. The degradation of starch was found to be minor due to the use of long‐chain fatty acid and relatively low reaction temperatures. The dissolution, gelatinization, esterification, and recrystallization of starch in DES broke the particles into smaller ones and altered the crystal structure of native starch while the aggregation between particles was increased and the degree of crystallinity was decreased for the esterified starch with the length of carbon‐chain in the fatty acids.
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