Ultrasmall metal–organic frameworks (MOFs) may generate unique properties to expand the scope of applications. However, the synthesis is still a great challenge. Herein, we propose a strategy to ...synthesize ultrasmall MOFs by high gravity technology. With the aid of tremendous intensification of molecular mixing and mass transfer in high‐gravity field, six typical MOFs were obtained instantaneously in a continuous way. These samples are monodispersed with sub‐5 nm in size, smaller than the previously reported values and even close to the length of one crystal unit cell. As a proof‐of‐concept, catalytic activity for Knoevenagel reaction can be significantly enhanced using ultrasmall ZIF‐8. Conversion time of benzaldehyde was decreased by 94 % or 75 % compared to those using conventional or hierarchically porous ZIF‐8. More importantly, this approach is readily scalable with the highest space‐time yield for nano‐MOFs, which may promote the convenient synthesis and practical applications of ultrasmall MOFs in large‐scale.
A series of ultrasmall MOF nanoparticles could be instantaneously synthesized in a continuous way by a facile and universal strategy with the aid of high gravity intensification technology. This approach is readily scalable with the highest space‐time yield for nano‐MOFs. The as‐prepared ultrasmall ZIF‐8 exhibits extremely high catalytic activity for the Knoevenagel reaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The development of green synthetic approaches is one of the key materials challenges in moving toward semiconductor quantum dots (QDs) for large-scale production and commercial applications. This ...article presents a comprehensive overview on the synthesis of colloidal QDs prepared via chemical approaches in solution phase, with emphasis on green routes which possess the advantages of environment-friendly raw materials, simple operation process, and robust mass-scale production. The approaches for the synthesis of QDs in batch reactors are summarized, including hot-injection organometallic synthesis, noninjection organometallic synthesis, aqueous synthesis and biosynthesis approaches, with some of the concerns on their limitations for scale-up, followed by some continuous synthetic methods aiming for reproducible and large-scale production. Current advances in continuous synthesis of QDs by microfluidic devices, high-gravity reactors, and spray-based techniques are briefly introduced. We also provide some insights into challenges and opportunities based on our own understanding of this field.
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IJS, KILJ, NUK, PNG, UL, UM
Selectively separating CH4 from N2 in natural gas purification is extremely important, but challenging. Herein, a copper‐based metal–organic framework (MOF) NKMOF‐8‐Me with inert pore environment was ...reported for efficient CH4/N2 separation. Adsorption results show that this material owns the highest CH4 uptake (1.76 mmol/g) and initial adsorption heat (Qst0) of CH4 (28.0 kJ/mol) as well as difference in Qst0 (9.1 kJ/mol) among all materials with good water stability. Breakthrough experiments confirm that this MOF can completely separate the CH4/N2 mixture with the highest CH4/N2 breakthrough selectivity (7.8) reported so far. Theoretical calculations reveal the separation mechanism is the short average distance between CH4 and pore wall, resulting in a stronger adsorption affinity for CH4. In addition, this MOF exhibits highly structural stability and regeneration. These results guarantee this MOF as a promising adsorbent for the recovery of CH4 from coalbed methane.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sustainable solutions on fabricating and using a face mask to block the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spread during this coronavirus pandemic of 2019 (COVID‐19) are ...required as society is directed by the World Health Organization (WHO) toward wearing it, resulting in an increasingly huge demand with over 4 000 000 000 masks used per day globally. Herein, various new mask technologies and advanced materials are reviewed to deal with critical shortages, cross‐infection, and secondary transmission risk of masks. A number of countries have used cloth masks and 3D‐printed masks as substitutes, whose filtration efficiencies can be improved by using nanofibers or mixing other polymers into them. Since 2020, researchers continue to improve the performance of masks by adding various functionalities, for example using metal nanoparticles and herbal extracts to inactivate pathogens, using graphene to make masks photothermal and superhydrophobic, and using triboelectric nanogenerator (TENG) to prolong mask lifetime. The recent advances in material technology have led to the development of antimicrobial coatings, which are introduced in this review. When incorporated into masks, these advanced materials and technologies can aid in the prevention of secondary transmission of the virus.
Masks are critical during the coronavirus pandemic of 2019 (COVID‐19), and there is a huge demand for them globally. Many countries use cloth masks and 3D‐printed masks as substitutes, but the filtration efficiencies are unqualified. Herein, various new mask technologies and advanced materials, including metal nanoparticles, graphene, metal organic framework (MOF), and triboelectric nanogenerator (TENG) are reviewed, to deal with critical shortages, cross‐infection, and secondary transmission risk of masks.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Zr‐based metal‐organic framework (Zr‐MOF) nanoparticles (NPs) have attracted extensive research thanks to their outstanding thermal and chemical stability, but their efficient synthesis is still ...challenging. Here, high‐quality Zr‐MOF NPs with tunable and uniform particle sizes can be successfully fabricated within 30 min by high‐gravity technology with high yields. Significantly, the rapidly milder preparation of UiO‐66 NPs can also be achieved at 90 or 70°C. This strategy has been extended to the synthesis of other Zr‐MOF NPs. Furthermore, the water vapor adsorption properties of obtained UiO‐66 NPs display a size‐dependent effect. The 70 nm UiO‐66 NPs have the highest adsorption capacity of 625 mg g−1 among unmodified UiO‐66 reported so far, and manifest 2.0–2.8 times faster water adsorption rate than the micron ones. This study provides a feasible method for the efficient and mild preparation of MOFs nanoparticles, which may promote the synthesis and applications of nano‐sized MOFs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Organic fluorescent dyes have attracted wide interest because of their high photoluminescence quantum efficiencies. However, there are several application limitations arising from their ...hydrophobicity, poor dispersity and large particle sizes. These problems can be improved by preparing nanoparticles with a small size. Herein, we present a continuous approach to efficiently prepare an aqueous nanodispersion of water‐insoluble organic fluorescent dye Nile red (NR) with monodispersed and uniform nanoparticles (35 nm) by high‐gravity antisolvent precipitation in a rotating packed bed (RPB). In contrast, NR nanodispersions prepared using a traditional batch stirred tank (ST) had a broad size distribution (20–150 nm). Due to its small size effect and good dispersity in water, the RPB nanodispersion displayed significantly increased saturation solubility and much stronger fluorescent intensity compared to raw NR, and was obviously superior to the ST counterpart. Furthermore, NR nanodispersions were mixed with ink to draw fluorescent patterns on paper for counterfeit labeling.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Process intensified synthetic approach for synthesizing gadolinium and cerium co‐doped yttrium aluminum garnet (GdYAG:Ce) phosphors in white light‐emitting diodes (wLED) is developed. By using a ...high‐gravity rotating packed bed (RPB) reactor for preparation of sol–gel precursors, the significantly enhanced molecular mixing allows precise control and tuning of dry gel with designed structure to obtain nanosized particles of GdYAG:Ce precursors, which are prone to low temperature quick sintering process and therefore reduce the energy consumption of the electric furnace 76% compared to solid phase method. By analyzing the effect of cycling times and high gravity levels of RPB reactor on sintering and crystallization, sintering condition for emission spectrum adjustable GdYAG:Ce phosphors is optimized. Prototype devices based on blue chips and GdYAG:Ce phosphors exhibit high color rendering index of 83.8 and low correlation color temperature of 5357 K that are beneficial for creating a healthy and comfortable lighting environment.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Practical application of versatile nanomaterials to food engineering is desirable. In this study, highly encapsulated curcumin‐loaded shellac (Cur@Lac) nanoparticles are efficiently prepared via a ...rotating packed bed (RPB). In this modified co‐precipitation process, the morphology of Cur@Lac nanoparticles is systematically investigated under experimental parameters involving the high‐gravity level, the volume of antisolvent and the concentration of shellac. By virtue of the highly structured polymeric ester matrices of shellac and adequate supersaturation brought from RPB on a microscale, the obtained Cur@Lac nanoparticles with uniform size exhibit high encapsulation efficiency of over 96%. After 2 months of storage at room temperature, the aqueous Cur@Lac nanodispersions exhibit long‐term stability with no agglomeration or sedimentation, and the final retention rate of curcumin was over 85%. Colored drinks of fruit syrup (pH = 4.0), fruit soda (pH = 6.0), and soda water (pH = 8.3) are prepared by using the Cur@Lac as the colorant, which possessed orange‐yellow color. The nanocomposites of alkali‐sensitive indicators based on cellulose paper and gelatin film demonstrated in the work show promising application value for sensing of alkaline solution and gas of perishable food.
Curcumin‐loaded shellac nanoparticles are successfully prepared by modified co‐precipitation method in a rotating packed bed. As the amphipathic matrix, biopolymer (shellac) encapsulates a sensitive multifunctional material (curcumin) with high encapsulation efficiency and stability. The composite nanoparticles can be used as natural colorants dispersed in daily drinks and applied for sensing of alkaline solution and gas of perishable food.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cotton stalk bark fiber (CSBF) was extracted at high temperature and under high pressure, under the condition of the alkali content of 11 wt%. Experimental results proved that the extraction yield of ...CSBF was 27.3 wt%, and the residual alkali concentration was 2.1 wt%. Then five kinds of modifiers including methyl methacrylate (MMA), MMA plus initiator, epoxy propane, copper ethanolamine, and silane coupling agent were chosen to modify the surface of CSBF. It was found by measuring water retention value (WRV) that these five kinds of modifiers were all effective and the silane coupling agent was best modifier among all. The optimal modifying conditions of silane coupling agent were obtained: modifier concentration was 5%, the mixing temperature was 20°C, the mixing time was 1 h, and vacuum drying time was 1 h. Under the optimal condition, the WRV of the modified CSBF was 89%. It is expected that these modified CSBF may be a filler with strengthening effect in wood plastic composites (WPC) fields.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Platinum (Pt)‐based alloys have received considerable attention due to their compositional variability and unique electrochemical properties. However, homogeneous element distribution at the ...nanoscale, which is beneficial to various electrocatalytic reactions, is still a great challenge. Herein, a universal approach is proposed to synthesize homogeneously alloyed and size‐tunable Pt‐based nanoflowers utilizing high gravity technology. Owing to the significant intensification of micro‐mixing and mass transfer in unique high gravity shearing surroundings, five typical binary/ternary Pt‐based nanoflowers are instantaneously achieved at room temperature. As a proof‐of‐concept, as‐synthesized Platinum‐Silver nanoflowers (PtAg NFs) demonstrate excellent catalytic performance and anti‐CO poisoning ability for anodic methanol oxidation reaction with high mass activity of 1830 mA mgPt−1, 3.5 and 3.2 times higher than those of conventional beaker products and commercial Pt/C, respectively. The experiment in combination with theory calculations suggest that the enhanced performance is due to additional electronic transmission and optimized d‐band center of Pt caused by high alloying degree.
A universal approach for the highly‐efficient fabrication of homogeneously alloyed Platinum‐based alloy is proposed by high‐gravity technology. The greatly strengthened micro‐mixing and mass transfer can remarkedly improve the alloying degree and electronic structure. The optimized mass activity of rotating packed bedproducts for methanol oxidation reaction is 3.5 and 3.2 times higher than those of conventional beaker products and Pt/C.
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