Paper-based sensor based on lead-free manganese halide for the determination of water content in organic solvents.

A highly stable and luminescent lead-free manganese(II) halide hybrid MnBr4(TMN)2 (C34H42Br4MnN4) was designed and synthesized by introducing a large cationic organic spacer. The MnBr4(TMN)2 displays high luminescence with quantum yields up to 77% and possesses turn-off fluorescence behavior (Ex/Em=365/546 nm) for water. These properties make the MnBr4(TMN)2 a promising candidate as an alternative indicator for the detection of water with potential applications for the fabrication of LEDs. Herein, a paper-based sensor based on MnBr4(TMN)2 is described for the determination of water content in organic solvents. The mechanism of water sensing can be tentatively explained by fluorescence quenching originating from the destruction of water due to the Mn-Br bonds of MnBr4(TMN)2. The MnBr4(TMN)2-based paper sensor exhibits an excellent discrimination ability of water content in the range 0-25.0% with a detection limit of 0.27%. Satisfactory recoveries (94.91±4.09% to 103.23±2.38%) are obtained in spiked ethanol solvent samples, which demonstrate that the MnBr4(TMN)2-based paper sensor is capable of detecting water content in real ethanol solvent samples.

Spatial Separation of Electrons and Holes among ZnO Polar {0001} and {101Ì 0} Facets for Enhanced Photocatalytic Performance.

Spatial separation of electrons and holes is critical for improving their photocatalytic performance, which is ascribed to the suppressed photoinduced carriers' recombination among facets. In this work, the ZnO-Au-MnO x heterogeneous nanostructure photocatalyst was prepared by photodepositing Au and MnO x on the ZnO polar {0001} and {101̅0} crystal facets, respectively. The photocatalytic performance of ZnO-Au-MnO x was higher than ZnO and ZnO-Au for the degradation of rhodamine B dye under UV light irradiation. Due to the potential difference between different crystal planes of zinc oxide, electrons and holes will migrate to different crystal planes of zinc oxide. This will lead to the deposition of Au and MnO x on different crystal facets of zinc oxide. The efficient photoinduced carrier separation of ZnO-Au-MnO x resulted in the high photocatalytic activity, which is well supported by photoelectrochemical and photoluminescence analyses. The intermediated species formed during the reaction were investigated by high performance liquid chromatography. The reaction mechanism was investigated by radical trapping experiments and electron spin resonance analysis. The special structure of selective deposition of redox cocatalysts on the different facets should be promising and intriguing for designing highly efficient photocatalysts.

Fluorometric determination of ziram using CsPbBr3 quantum dots.

A strategy based on CsPbBr3 quantum dots (QDs) is described for the determination of ziram pesticide. A facile and inert gas-free method was used for the synthesis of CsPbBr3 QDs. The obtained CsPbBr3 QDs displayed turn-off fluorescence behavior for ziram. The fluorescence intensity of the CsPbBr3 QDs (Ex/Em = 365/516 nm) was inversely proportional to the concentration of ziram (0.10 to 50.0 ppm) with a detection limit of 0.086 ppm. Notably, satisfactory recoveries (100 ± 0.25 to 107 ± 5.72%) were obtained in spiked fruit samples, which demonstrated that this method is capable of detecting ziram in real samples. In addition, the mechanism for the detection of ziram was investigated in detail. According to the results, this mechanism can be tentatively explained by fluorescence quenching originating from the increased surface defects and the structural changes of the CsPbBr3 QDs. The detection ability of this strategy shows promising applicability in food safety.

Broadband Solar Absorber Based on Square Ring cross Arrays of ZnS.

Solar energy is an inexhaustible clean energy. However, how to improve the absorption efficiency in the visible band is a long-term problem for researchers. Therefore, an electromagnetic wave absorber with an ultra-long absorption spectrum has been widely considered by researchers of optoelectronic materials. A kind of absorbing material based on ZnS material is presented in this paper. Our purpose is for the absorber to achieve a good and wide spectrum of visible light absorption performance. In the wide spectrum band (553.0 THz-793.0 THz) of the absorption spectrum, the average absorption rate of the absorber is above 94%. Using surface plasmon resonance (SPR) and gap surface plasmon mode, the metamaterial absorber was studied in visible light. In particular, the absorber is insensitive to both electric and magnetic absorption. The absorber can operate in complex electromagnetic environments and at high temperatures. This is because the absorber is made of refractory metals. Finally, we discuss and analyze the influence of the parameters regulating the absorber on the absorber absorption efficiency. We have tried to explain why the absorber can produce wideband absorption.

Novel covalent organic framework/PVDF ultrafiltration membranes with antifouling and lead removal performance.

Membrane separation technology is recognized as a competitive approach to remove Pb2+ from water system due to its high efficiency and low operating cost. In present study, a simple and facile approach was developed to fabricate covalent organic framework (COF) modified PVDF ultrafiltration membranes with comprehensive antifouling property and superior Pb2+ removal ability. Herein, COF was synthesised in a homogenous PVDF/DMAc solution to fabricate hydrophilic COF modified PVDF ultrafiltration membranes with the Pb2+ removal property. The filtration test demonstrated that the COF modified PVDF ultrafiltration membranes exhibited excellent antifouling property and high water flux. Moreover, the membranes showed remarkable potential for treating Pb2+-containing water. The removal efficiency was determined at 92.4%, and its removal efficiency was 87.5% at the fourth treatment cycle with Pb2+-containing water. The present work provides a valuable platform for further development of efficient composite membranes for the treatment of Pb2+-containing water.

Constructing atomic layer g-C3N4-CdS nanoheterojunctions with efficiently enhanced visible light photocatalytic activity.

Ultrathin two dimensional (2D) materials have triggered extensive interest for their exceptional properties and potential applications. Herein, atomic layer graphitic carbon nitride (g-C3N4) was obtained by a simple ultrasonic exfoliation approach, and cadmium sulfide (CdS) nanoparticles were successfully grown on these ultrathin g-C3N4 nanosheets (UCNNS) via a facile solvothermal method. The as-prepared UCNNS-CdS nanocomposite exhibits significantly enhanced photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The enhancement of the photocatalytic activity should be attributed to the well-matched band structure and intimate contact interfaces between the UCNNS and CdS, which lead to the effective transfer and separation of the photogenerated charge carriers. The mechanism for the photodegradation of MO by the composite was also investigated in this study. This study highlights the potential applications of atomic layer g-C3N4 based photocatalysts, and we hope our work may provide a new insight for the construction of photocatalysts with efficient visible light activity.

Solvents mediated-synthesis of BiOI photocatalysts with tunable morphologies and their visible-light driven photocatalytic performances in removing of arsenic from water.

BiOI photocatalysts with tunable morphologies from 2D laminar structure to 3D hierarchitectures have been prepared by a hydrothermal or solvothermal way using four kinds of solvents: water, ethanol, ethylene glycol and glycerol (these solvents are abbreviated as H2O, ETH, EG, and GLY hereinafter). The viscosity of the solvents plays a key role to the evolution on the morphologies and performances of BiOI samples. The BiOI synthesized in GLY exhibits excellent visible-light photocatalytic performances toward As(III), which is highly increased to that of N-TiO2. Further investigation reveals that the surface characteristics of BiOI nanosheets, the thickness of the nanosheets, and the way by which they integrate together play important roles in photocatalytic reaction process. The main active species is detected as O2(-). Considering about the practical use, the BiOI synthesized in GLY is also work under illumination of natural sunlight, and total arsenic concentration can be decreased even below 10µg/L from 1mg/L As(III) aqueous solution within 3h, which has reached the drinking water standard (0.01mg/L). Moreover, its stable performance also shows its great potential application value in the wastewater treatment.