Polymers
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2020
·Vol. 12
·期 10
·2268
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IF 3.426
Song Feng,Junqin Wang,Lihua Zhang,Qin Chen,Wang Yue,Ni Ke,Haibo Xie
Currently, controlled release formulations (CRFs) of pesticides in response to biotic and/or abiotic stimuli have shown great potential for providing “on-demand” smart release of loaded active ingredients. In this study, amphiphilic biopolymers were prepared by introducing hydrophobic (7-diethylaminocoumarin-4-yl)methyl succinate (DEACMS) onto the main chain of hydrophilic carboxymethylchitosan (CMCS) via the formation of amide bonds which were able to self-assemble into spherical micelles in aqueous media and were utilized as light-responsive nanocarriers for the controlled release of pesticides. FTIR and NMR characterizations confirmed the successful synthesis of the CMCS-DEACMS conjugate. The critical micelle concentration (CMC) decreased with the increase in the substitution of DEACMS on CMCS, which ranged from 0.013 to 0.042 mg/mL. Upon irradiation under simulated sunlight, the hydrodynamic diameter, morphology, photophysical properties and photolysis were researched by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), UV-vis absorption spectroscopy and fluorescence spectroscopy. Moreover, 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model pesticide and encapsulated into the CMCS-DEACMS micelles. In these micelle formulations, the release of 2,4-D was promoted upon simulated sunlight irradiation, during which the coumarin moieties were cleaved from the CMCS backbone, resulting in a shift of the hydrophilic–hydrophobic balance and destabilization of the micelles. Additionally, bioassay studies suggested that this 2,4-D contained which micelles showed good bioactivity on the target plant without harming the nontarget plant. Thereby, the light-responsive CMCS-DEACMS micelles bearing photocleavable coumarin moieties provide a smart delivery platform for agrochemicals.Keywords:carboxymethyl chitosan micelles;light-responsive;coumarin;2,4-D;controlled release;pesticide
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RSC Advances
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2020
·Vol. 10
·期 44
·26246-26255
·
IF 3.119
Zhu Ding,Shuo Wang,Xue Chang,Dan-Hong Wang,Tianhao Zhang
Photocatalytic nitrogen fixation has attracted extensive attention in recent years. Studies have shown that catalytic materials with O, N and other defects can effectively reduce the bond energy of NN triple bond when N2 is adsorbed on the defects. As an outstanding non-metallic catalyst, g-C3N4 has been widely studied in the field of photocatalytic catalysis, and the nitrogen-defected C3N4 shows promoted photocatalytic activity. Herein, nano-size MOF-74 particles (<20 nm) was dispersed on nitrogen-defected C3N4 thin film (∼4 nm) via a simple sol–gel method. The combination of Nano-MOF and defected film C3N4 could effectively improve the photocatalytic activity of nitrogen fixation through Z-scheme mechanism compared with pure defected film C3N4.
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Journal of Physics Communications
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2020
·Vol. 4
·期 4
·045016
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IF 0
Jiahu Wei,Feng Li,Chun Chang,Qin Zhang
Indium-rich environmentally-friendly quantum dots (QDs) have received widespread attention due to the absence of cadmium. In this paper, AgInS2 (AIS) QDs are synthesized by hot injection method. By adjusting the ratio of indium/silver (In/Ag = 1, 2, 3, 4, 5), the AIS QDs exhibit a blue shift from 868 nm to 603 nm with the indium composition increases. Therein, the AIS QDs with the ratio of In/Ag = 4 show a highest photoluminescent (PL) quantum yields (QYs) up to 57%. AIS QDs are coated with ZnS shell to passivate the surface defects, and the PL QYs of obtained core/shell AIS/ZnS QDs is increased to 72%. By using these AIS/ZnS QDs as light emitters, light emitting diodes are assembled with a stacked multi-layer structure ITO/PEDOT:PSS/Poly-TPD/QDs/ZnO:Mg/Al. The resulted electroluminescent (EL) device exhibits a maximum external quantum efficiency (EQE) of 1.25% and an open circuit voltage of 4.6 V corresponding to a maximum brightness of 1120 cd m−2. Although the performances of the as fabricated AIS/ZnS-based device lag much behind than those of the Cd-based ones, they are expected to be enhanced with much more studies on the synthesis of the QDs and the optimization of device structure.
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Nanomaterials
·
2020
·Vol. 10
·期 4
·805
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IF 4.324
Bo Zhang,Xiangfeng Peng,Zhao Wang
Composites of g-C3N4/TiO2were one-step prepared using electron impact with dielectric barrier discharge (DBD) plasma as the electron source. Due to the low operation temperature, TiO2by the plasma method shows higher specific surface area and smaller particle size than that prepared via conventional calcination. Most interestingly, electron impact produces more oxygen vacancy on TiO2, which facilitates the recombination and formation of heterostructure of g-C3N4/TiO2. The composites have higher light absorption capacity and lower charge recombination efficiency. g-C3N4/TiO2by plasma can produce hydrogen at a rate of 219.9 μmol·g−1·h−1and completely degrade Rhodamine B (20mg·L−1) in two hours. Its hydrogen production rates were 3 and 1.5 times higher than that by calcination and pure g-C3N4, respectively. Electron impact, ozone and oxygen radical also play key roles in plasma preparation. Plasma has unique advantages in metal oxides defect engineering and the preparation of heterostructured composites with prospective applications as photocatalysts for pollutant degradation and water splitting.Keywords:dielectric barrier discharge plasma;oxygen vacancy;g-C3N4/TiO2;photodegradation;H2evolution
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Nanoscale
·
2020
·Vol. 12
·期 16
·8711-8719
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IF 6.895
Weilin Zheng,Qun Wan,Qinggang Zhang,Mingming Liu,Congyang Zhang,Bo Wang,Long Kong,Liang Li
Nickel oxides exhibit a great potential as hole transport layers for the fabrication of efficient perovskite light-emitting diodes (LEDs) due to their high carrier mobility and good energy band matching with perovskite nanocrystals. In this work, nickel oxides were directly decorated on the CsPbBr3 nanocrystal surface through adsorption and a sequential oxidation treatment. The resulting sample shows a high photoluminescence quantum-yield of 82%. The LED using CsPbBr3 nanocrystals with nickel oxides achieves a high external quantum efficiency (EQE) of up to 16.8% with a low turn-on voltage of 2.8 V, which is much superior to that of the counterpart LED based on pristine CsPbBr3 nanocrystals (EQE = 0.7%, turn-on voltage = 5.6 V). The excellent performance of the nickel oxide decorated CsPbBr3 nanocrystal device could be attributed to the better energy level matching between the decorated nanocrystals and the transport layers of the device and more balanced charge carrier injection. Furthermore, the operational lifetime of the nickel oxide decorated CsPbBr3 nanocrystal device is 40 times longer than that of the pristine CsPbBr3 nanocrystal device.
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Inorganic Chemistry Frontiers
·
2020
·Vol. 7
·期 14
·2629-2636
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IF 5.958
Guoan Lin,Ran Wang,Tongcheng Cao,Liangxi Yuan,Xiaoxiang Xu
With an absorption edge as far as 690 nm, SrNbO2N holds great promise for solar energy conversion. However, very poor photocatalytic activity is generally seen for SrNbO2N, limiting its practical applications as a photocatalyst. In this work, SrNbO2N is modified by introducing Zr at B sites, i.e. SrNb1−xZrxO2+yN1−y (0 ≤ x ≤ 1), which are then investigated as photocatalysts for water oxidation reactions. Zr modification not only induces porous microstructures and inhibits the formation of Nb4+ defects, but it also ameliorates the surface hydrophilicity of SrNbO2N. Clear improvements in photocatalytic water oxidation have been realized after Zr modification and an apparent quantum efficiency of as high as 1.44% has been achieved. Further analysis of the band edge alignments suggests that Zr modification positively shifts the valence band edge of SrNbO2N, which favors water oxidation reactions.
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BULLETIN OF THE KOREAN CHEMICAL SOCIETY
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2020
·Vol. 41
·期 5
·552-557
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IF 0.611
Shan Li,Zhongping Chen,Datong Wu,Yong Qin,Yong Kong
A novel composite of graphene quantum dots functionalized Sb 2 WO 6 (GQDs/Sb 2 WO 6 ) was prepared by an electrostatic self-assembly method and used as a photocatalyst for the degradation of an organic pollutant. The resulting GQDs/Sb 2 WO 6 was characterized by electron microscopy and optical measurements. The photocatalytic activity of GQDs/Sb 2 WO 6 was investigated by degrading methyl orange (MO) under UV-light and visible-light irradiation. Compared with pure Sb 2 WO 6 , enhancement of the photocatalytic performance of GQDs/Sb 2 WO 6 was achieved, and the degradation efficiency for MO was almost 100% within 3 h under UV-light irradiation and 71.4% within 3 h under visible-light irradiation. The photocatalytic degradation mechanism of GQDs/Sb 2 WO 6 was illustrated by free radical and hole scavenging experiments, and the main active species were confirmed to be holes (h + ) and superoxide anion radicals (O 2 · − ). Moreover, the GQDs/Sb 2 WO 6 composites exhibited high recyclability and stability and had potential application for decomposing other organic contaminants in water.
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TALANTA
·
2020
·
IF 5.339
Li Jun Gong,Yuan Fang Li,Hong Yan Zou,Cheng Zhi Huang
Heparin (Hep) is a mucopolysaccharide sulfate anticoagulant drug widely used in clinic and thus the quantification of Hep concentration is of great significance. In this work, a simple resonance light scattering (RLS) method for the determination of Hep concentration using plasmonic copper selenide nanoparticles (Cu 2-x Se NPs) was developed. The positively-charged Cu 2-x Se NPs capped by cetyltrimethyl ammonium bromide (CTAB) were aggregated by negatively-charged Hep, consequently inducing a significant enhancement in the RLS signals of plasmonic Cu 2-x Se NPs. Under the optimal reaction conditions, the increased RLS intensity is linearly correlated with the concentrations of Hep in the range of 0.01–0.60 μg mL −1 (R 2 = 0.999), with a low detection limit (LOD) of 4.0 ng mL −1 (3σ). This method offered a simple, sensitive and selective strategy for determining Hep, which can be further successfully applied to quantify Hep in the heparin sodium injection.
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RSC Advances
·
2020
·Vol. 10
·期 20
·11851-11860
·
IF 3.119
Rongjing Wang,Yaru Li,Qianyi Sun,Kaihua Gao,Yufu Pan,Meng Li,Feitian Zhang,Ping Na
In this paper, a new photocatalyst with TiO2 nanospheres decorated on ultrathin layered thiostannate H4xK2xSn2−xS4+x (X = 0.5–0.6, HKTS) nanosheets was successfully synthesized by a facile solvothermal method combined with the hydrolysis of tetrabutyl titanate and it was denoted as HKTS/TiO2. By adjusting the content of tetrabutyl titanate, composites with different Sn/Ti molar ratios were prepared. The composites were applied for RhB degradation under visible light irradiation, and the optimum proportion of HKTS/TiO2 was obtained. The results of X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that TiO2 was successfully decorated on HKTS nanosheets. The combination of TiO2 and HKTS extended the absorption wavelength of TiO2 from UV to visible light range, and the separation efficiency of photoexcited electron–hole pairs was also enhanced. The photocatalytic degradation rate of RhB over HKTS/TiO2-1.0 was almost 97.9% after 60 min illumination, which was higher than those of HKTS and pure TiO2. The photocatalyst exhibited excellent reusability and stability as the degradation rate of RhB was 95.7% even after three cycles. The photocatalytic mechanism experiment indicated that ·O2− and h+ played a dominant role in the photocatalytic process. All these results indicate that the newly fabricated HKTS/TiO2 composites provide a high-performance photocatalyst for waste water treatment, and the application of thiostannate can be extended to the field of photocatalytic materials.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 137
·期 44
·49375
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IF 2.52
Liai Yang,Ting Zhang,Wei Sun
To construct an actuator with biocompatibility and potential use in biomedicine field, a light-driven actuator composed of reduced graphene oxide (rGO)/poly (N-isopropyl acrylamide) (PNIPAM) and poly (ethylene glycol) diacrylate (PEGDA) hydrogel is constructed. First, rGO/PNIPAM hydrogel is prepared by free radical polymerization and l -ascorbic acid reduction, of which the surface temperature increases quickly under near-infrared (NIR) laser indicating the efficient photothermal conversion of rGO. The results of cytotoxicity tests demonstrate that rGO/PNIPAM is biocompatible and has no obvious toxicity to myoblast line C2C12 cells. Second, bilayer hydrogel composed of rGO/PNIPAM and PEGDA is prepared using a similar method layer-by-layer. The bilayer strip bends towards rGO/PNIPAM under NIR laser. The bending is improved after reduction. The laser power density has a strong impact on the bending rate and degree. The reversible bending deformation indicates the structural stability. All the above results approve that the bilayer actuator has great potential to be applied in biomedicine fields such as organ-on-chip, drug-carrier, or surgical aid.
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DALTON TRANSACTIONS
·
2020
·Vol. 49
·期 18
·6074-6083
·
IF 4.174
Rongyun Jiang,Jian Yang,Yangqi Meng,Duanting Yan,Chunguang Liu,Changshan Xu,Yuxue Liu
Zn2Ga3−x−yCrxNdyGe0.75O8 (ZGGO:Crx,Ndy) persistent luminescent nanoparticles (PLNPs) (x = 0, 0.02; and y = 0, 0.01, 0.02, 0.03, 0.04) were synthesized via a hydrothermal method in combination with a following heat treatment under vacuum. The effects of Nd3+ concentration on chemical composition, size distribution, luminescence property, the persistent energy transfer from Cr3+ to Nd3+ and afterglow imaging were studied in detail. When the Nd3+ concentration was increased from 0 to 0.04, the particle size increased from 45.4 to 86.2 nm. The afterglow emissions in the NIR-I (696 nm) and NIR-II (1067 nm) regions, which are ascribed to the 2E, 4T2 → 4A2 transitions of Cr3+ and the 4F3/2 → 4I11/2 transition of Nd3+, respectively, were simultaneously acquired after stopping the 635 nm excitation. Among the nanoparticles with different concentrations, ZGGO:Cr0.02,Nd0.02 exhibits the strongest NIR-II afterglow intensity and the corresponding energy transfer efficiency from Cr3+ to Nd3+ is found to be 25.9%. In addition, enhanced X-ray excited afterglow imaging can be observed in Nd3+/Cr3+ codoped nanoparticles dispersed in water, human serum albumin solution and simulated lysosomal environment compared to the Cr3+ singly doped nanoparticles. Renewable NIR afterglow imaging was realized through an X-ray reexcitation strategy. In particular, both the X-ray excitation strategy accompanied by NIR-I afterglow emission and the red light (635 nm) excitation strategy accompanied by NIR-II afterglow emission exhibit high tissue penetration capability. This study provides a further understanding of how to develop a suitable strategy for realizing deep tissue autofluorescence-free bioimaging.
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JOURNAL OF HAZARDOUS MATERIALS
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2020
·
IF 9.038
Enqi Yu,Jing Chen,Hongpeng Jia
LaTi 1− x Mn x O 3+ δ ( x = 0.2 and 0.4) perovskite-type catalysts are synthesized by acrylamide polymerization route and etched with diluted HNO 3 for oxidation of toluene as one of typical volatile organic compounds (VOCs). The substitution of Mn cations improves catalytic activity (toluene conversion increased from 0 to 50.6% by substituting 40% of Ti cations with Mn cations) by improving abilities of light absorption and light-to-heat conversion, and acid etching further promotes catalytic activity (toluene conversion increased from 50.6%–95.6% for LaTi 0.6 Mn 0.4 O 3+ δ ) by enlarging specific surface area, generating more surface active oxygen, strengthening mobility of surface oxygen, and improving low-temperature reducibility. To explore the origin of the light-driven photothermocatalytic activity of A-LaTi 0.6 Mn 0.4 O 3+ δ by EPR analysis, O 2 desorption and H 2 consumption, we find that the light is not only as a thermal source to provide energy for toluene oxidation but also can promote oxidation reaction by photoactivation.
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