Facile Method Research Articles

Generation of precision microstructures based on reconfigurable photoresponsive hydrogels for high-resolution polymer replication and microoptics

Microstructured molds are essential for fabricating various components ranging from precision optics and microstructured surfaces to microfluidics. However, conventional fabrication technology such as photolithography requires expensive equipment and a large number of processing steps. Here, we report a facile method to fabricate micromolds based on a reusable photoresponsive hydrogel: Uniform micropatterns are engraved into the hydrogel surface using photo masks under UV irradiation within a few minutes. Patterns are replicated using polydimethylsiloxane with minimum feature size of 40 μm and smoothness of Rq ~ 3.4 nm. After replication, the patterns can be fully erased by light thus allowing for reuse as a new mold without notable loss in performance. Utilizing greyscale lithography, patterns with different height levels can be produced within the same exposure step. We demonstrate the versatility of this method by fabricating diffractive optical elements devices and a microlens array and microfluidic device with 100 µm wide channels.

Design and Synthesis of a Robust and Multifunctional Superhydrophobic Coating with a Three-Dimensional Network Structure on a Paper-Based Material.

A fundamental challenge in artificial superhydrophobic papers is their poor resistance to mechanical abrasion, which limits their practical application in different fields. Herein, a robust and multifunctional superhydrophobic paper is successfully fabricated via a facile spraying method by combining silver nanowires and fluorinated titania nanoparticles through a common paper sizing agent (alkyl ketene dimer) onto paper. It is shown that the surface of the paper-based material presents a three-dimensional network structure due to the cross-linking of silver nanowires with a high aspect ratio. Further hydrophilic and hydrophobic performance test results show that it exhibits exceptional water repellency, with a desirable static contact angle of 165° and roll-off angle of 6.2°. The superhydrophobic paper showcases excellent mechanical durability and maintains its superhydrophobicity even after enduring 130 linear sandpaper abrasion cycles or high-velocity water jetting impact benefited from interfacial van der Waals and hydrogen bonding. Simultaneously, the robust superhydrophobic surface can effectively prevent the penetration of acid or alkali solutions, as well as UV light, resulting in excellent chemical stability. Additionally, the superhydrophobic paper offers supplementary features such as self-cleaning, electrical conductivity, and antibacterial capability. Further development of this strategy paves a way toward next-generation superhydrophobic paper composed of nanostructures and characterized by multiple (or additional) functionalities.

In situ loading of Ag2MoO4 nanoparticles onto oxygen-doped porous g-C3N4 for enhanced photocatalytic H2 evolution

Photogenerated carriers transfer and separation from the substance itself to produce spatial isolated electron-hole pairs is crucial for the utilization of composite photocatalysts in the field of photocatalytic hydrogen (H2) evolution. Herein, novel oxygen-doped porous graphitic carbon nitride (g-C3N4) micro-sheets decorated with Ag2MoO4 have been fabricated by a facile calcination method followed by in situ deposition strategy. The physicochemical properties of the obtained Ag2MoO4/OC3N4 composites were characterized via SEM, TEM, EDS, XRD, N2 adsorption-desorption, XPS, UV–vis DRS, PL, transient photocurrent response, and EIS, as well as DFT calculation. In addition, the effects of Ag2MoO4 content, type of scavengers, pH value of reaction solution and dosage of scavenger on photocatalytic H2 production were investigated. The results show that the modification of ammonium acetate thermal polymerization with urea could enhance the porosity of g-C3N4 and its specific surface area. The Ag2MoO4 nanoparticles are highly dispersed on the OC3N4 surface, reducing the charge transfer resistance at their interfaces. The OC3N4 photocatalyst achieves H2 yield of 8629.11 μmol/g over 2 h, which is about 1.46 times higher than that of C3N4. The H2 production amount over the optimal Ag2MoO4/OC3N4 composite photocatalyst (50 mg) is further enhanced to 16619 μmol/g, which is 1.93 and 180 times higher than that of OC3N4 and Ag2MoO4, respectively. The S-scheme charge transfer mechanism of Ag2MoO4/OC3N4 is proposed based on the DFT calculation. This work provides a facile and easy strategy to develop g–C3N4–based photocatalysts through adjusting chemical composition and photocatalytic properties.

Bound exciton engineering approach for tuning the thermal lensing phenomenon in anatase TiO2: Gd nanosystems

We report a comprehensive investigation of the third-order nonlinear interaction of femtosecond laser pulses with nanostructured anatase TiO2 doped with varying concentrations of gadolinium impurities. The samples were synthesized using a facile sol‒gel method. The physicochemical characteristics of the prepared samples were investigated using various analytical techniques, including XRD, SEM, TEM, SAED, UV‒Vis, PL and XPS. The average crystallite sizes of the pristine TiO2- and Gd (1, 2, and 3 %)-doped TiO2 nanoparticles were calculated to be 10.9, 9.2, 10.2 and 8.9 nm, respectively. The W-H plots also revealed average crystallite sizes in the range of 13.9, 16.6, 13.9 and 10.4 for pristine and Gd (1, 2, 3 %)-doped TiO2 nanoparticles. The lattice strain values for pristine and Gd (1, 2, and 3 %) doped TiO2 nanoparticles were computed as 0.00203, 0.00667, 0.0036 and 0.00262, respectively, from the W‒H plots. The average crystallite size was calculated to 9.2 nm from the TEM images using ImageJ software. The optical band gap values of pristine TiO2 and Gd (1, 2, and 3 %)-doped TiO2 nanoparticles were calculated to be 3.3, 3.23, 3.21 and 3.20 eV from the Kubelka–Munk function plot. The emission peaks of pristine and Gd(1,2,3 %) doped TiO2 nanoparticles were calculated as 3.2, 3.23, 3.26 and 3.32 eV from the photoluminescence spectra recorded at 330 nm photo excitation. The binding energies of the O1s, Ti2P and Gd4d peaks present in the survey scan of TiO2 nanoparticles doped with one weight percentage of Gd impurity were 528.79, 531.53, 457.53, 463.25 and 149.6 eV, respectively. The third-order nonlinear characteristics of the TiO2:Gd samples were probed using the ultrafast laser Z-scan technique. We observed that the density of bound excitons can be regulated by controlling the dopant concentration. The strong oscillatory interactions between photogenerated bound excitons, which act as dipole oscillators with large oscillating frequencies, were recorded using a single-beam femtosecond Z-scan. The third-order nonlinear susceptibility χ(3) for pristine and Gd(1,2,3 %)-doped TiO2 nanoparticles were calculated as 7.258 × 10-18, 9.4 × 10-18, 11 × 10-18 and 13 × 10-18 cm2/V2, respectively. The obtained results suggest that the thermal lensing phenomenon in nanostructured anatase TiO2 can be generated and effectively controlled using a band gap engineering technique. We determined that the small pump power in nonlinear media with controllable band fluctuations can produce large phase distortions in TiO2:Gd nanosystems. Our findings reveal that Gd doping induces controlled modification of the electronic structure of TiO2, leading to a tailored energy landscape for exciton formation and binding. These findings provide a novel approach for engineering systems of TiO2-based nanostructures for energy-efficient optical-limiting nanophotonic systems and optoelectronic-switching devices.

Formation of oxygen protective layer on monolayer MoS2 via low energy electron irradiation.

Monolayer molybdenum disulfide (MoS2) semiconductors are the new generation of two-dimensional materials that possess several advantages compared to graphene due to their tunable bandgap and high electron mobility. Several approaches have been used to modify their physical properties for optical device applications. Here, we report a facile and non-destructive surface modification method for monolayer MoS2 via electron irradiation at a low, 5 kV accelerating voltage. After electron irradiation, the results of Raman and photoluminescence spectroscopy confirmed that the structure remains unchanged. However, when the modified surface was illuminated with a 532 nm laser for a prolonged period, the PL intensity was quenched as a result of oxygen desorption. Interestingly, the PL intensity can be recovered when left in ambient conditions for 10 h. The analysis of the PL spectrum revealed a decrease of trion, which is consistent with the readsorbed O2 molecules on the surface that deplete electrons and lead to PL recovery. We attribute this effect to the enhancement of the n-type character of monolayer MoS2 after electron irradiation. The sensitive nature of the modified surface to oxygen suggests that this approach may be used as a tool for the fabrication of MoS2 oxygen sensors.

A S-scheme 0D/2D heterojunction formed by decorating Cd0.5Zn0.5S nanoparticles on Cu2MoS4 plates for efficient photocatalytic hydrogen generation

Rationally designing a Step-scheme (S-scheme) hetero-structured photocatalyst with high redox capability and separation efficiency of photoinduced carriers is considered as an attractive approach to address the shortcomings of single component and traditional hetero-structured photocatalyst. Herein, enlightened by the predictions of density functional theory (DFT), a unique S-scheme heterojunction photocatalyst was successfully fabricated by incorporating zero-dimensional (0D) Cd0.5Zn0.5S (CZS) on two-dimensional (2D) lamellar Cu2MoS4 (CMS) plates via a facile coprecipitation method, which substantially enhances the photocatalytic activity for hydrogen (H2) generation. CZS nanoparticles deposited on the surface of CMS nanoplates play a crucial role in creating highly intimate heterojunction interfaces and abundant exposed reaction sites, laying the foundation for improved photocatalytic performance. Furthermore, the significant difference in Fermi levels and band structures between CZS and CMS result in the formation of the internal electric field (IEF) and energy band bending at the interface of the heterojunction. This S-scheme charge transfer path enables 0D/2D CZS/CMS heterojunction possesses an exceptional capacity to maintain the robust redox potential and boosts the separation efficiency of light-induced carriers, as verified by DFT calculations and energy band structure analyses. As expected, the optimal heterojunction exhibits a satisfactory H2 generation rate of 13.1 mmol·g-1·h−1, which is nearly 7.7-fold higher than that of individual CZS. This study is expected to inspire the design of morphology-controlled hetero-structured photocatalyst with S-scheme charge transfer route for photocatalytic H2 generation.

A S-scheme 0D/2D heterojunction formed by decorating Cd0.5Zn0.5S nanoparticles on Cu2MoS4 plates for efficient photocatalytic hydrogen generation

Rationally designing a Step-scheme (S-scheme) hetero-structured photocatalyst with high redox capability and separation efficiency of photoinduced carriers is considered as an attractive approach to address the shortcomings of single component and traditional hetero-structured photocatalyst. Herein, enlightened by the predictions of density functional theory (DFT), a unique S-scheme heterojunction photocatalyst was successfully fabricated by incorporating zero-dimensional (0D) Cd0.5Zn0.5S (CZS) on two-dimensional (2D) lamellar Cu2MoS4 (CMS) plates via a facile coprecipitation method, which substantially enhances the photocatalytic activity for hydrogen (H2) generation. CZS nanoparticles deposited on the surface of CMS nanoplates play a crucial role in creating highly intimate heterojunction interfaces and abundant exposed reaction sites, laying the foundation for improved photocatalytic performance. Furthermore, the significant difference in Fermi levels and band structures between CZS and CMS result in the formation of the internal electric field (IEF) and energy band bending at the interface of the heterojunction. This S-scheme charge transfer path enables 0D/2D CZS/CMS heterojunction possesses an exceptional capacity to maintain the robust redox potential and boosts the separation efficiency of light-induced carriers, as verified by DFT calculations and energy band structure analyses. As expected, the optimal heterojunction exhibits a satisfactory H2 generation rate of 13.1 mmol·g-1·h−1, which is nearly 7.7-fold higher than that of individual CZS. This study is expected to inspire the design of morphology-controlled hetero-structured photocatalyst with S-scheme charge transfer route for photocatalytic H2 generation.

Solvothermal synthesis of micro-pillar shaped Ag2Se and its thermoelectric potential

Solvothermal method can synthesize ultralarge and high-performance thermoelectric powders with controllable structure, morphology, composition, and grain size. Here, we have developed a facile and surfactant-free solvothermal method for the synthesis of ultralarge Ag2Se powders. The as-synthesized Ag2Se powders exhibit the morphology of micro-pillar with the length ranging from several to hundreds of microns, and the average length-diameter ratio of ∼4.9. In as-synthesized Ag2Se micro-pillars, regardless of the high crystallinity and closely perfect Ag/Se ratio of ∼2, the highly localized lattice distortions and strain fields might indicate partial superionicity of room-temperature orthorhombic Ag2Se. Compositional and structural analysis after spark plasma sintering indicates the formation of additional Se vacancies due to Se sublimation during the sintering process, which leads to high carrier concentration of ∼1.3 × 1019 cm−3 and limits the room-temperature dimensionless figure of merit to ∼0.46. Further optimizing the carrier concentration to ∼1 × 1018 cm−3 can theoretically lead to high room-temperature dimensionless figure of merit of ∼1.4. Our study not only renders a facile solvothermal method for the synthesis of Ag2Se micro-pillars with extensive thermoelectric application potentials.

Enhanced remediation of PFAS-metal co-contaminated soil by ceramsite supported Fe3O4–MoS2 heterojunction as a high-performance piezocatalyst

In this study, a novel piezoremediation system was developed to remediate an actual soil co-polluted by high contents of per- and polyfluoroalkyl substances (PFAS, 5725 μg/kg soil) and heavy metals (6455 mg/kg soil). Two piezocatalysts, MoS2/ceramsite (MC) and Fe3O4–MoS2/ceramsite (FMC), were synthesized using a facile hydrothermal-coprecipitation method. These two materials were employed to treat the co-contaminated soil in soil slurry environment under sonication. FMC exhibited significantly higher piezoremediation performance than MC, wherein 91.6% of PFAS, 97.8% of Cr6+ ions and 81% of total metals (Cr, Cu, Zn and Ni) were removed from the soil after 50 min of the FMC piezoremediation process. FMC also exhibited the advantages of easy separation from the slurry phase and excellent reusability. In comparison with MC, the Fe3O4–MoS2 heterojunction in FMC can stabilize MoS2 particles on the surface of ceramsite granules, promote the separation of electron/hole pairs, accelerate charge transfer, therefore enhancing piezocatalytic performance. The electron spin resonance analysis and free radical quenching tests show that •OH was the dominant oxidative radical responsible for PFAS degradation. The count of bacteria and the bacterial community structure in the treated soil can be basically restored to the initial states after 30 days of incubation under nutrient stimulation. Overall, this study not only provides a deep insight on soil remediation process, but also offers an efficient and reliable technique for simultaneous decontamination of organic and metal pollutants in soil.

Catalytic Refining Lignin‐Derived Monomers: Seesaw Effect between Nanoparticle and Single‐Atom Pt

AbstractPt automatically adsorbed on oxygen vacancy of TiO2 via an in situ interfacial redox reaction, resulting in atomically dispersion of Pt on TiO2. In the upgrading of lignin‐derived 4‐propylguaiacol, single‐atom catalyst (SAC) Pt/TiO2−H achieved a conversion of 96.9 % and a demethoxylation selectivity of 93.3 % under 3 MPa H2 at 250 °C for 3 h, markedly different from the performance of nanoparticle counterpart that gave deep deoxygenation selectivity over 99.0 %. The high demethoxylation activity of SAC Pt/TiO2−H is mainly attributed to its weak hydrogen spillover capacity that suppressed the benzene ring hydrogenation and the deep deoxygenation. Additionally, SAC Pt/TiO2−H reduced the energy barrier of CAr−OCH3 bond cleavage and accordingly lowered the Gibbs free energy of the demethoxylation reaction. This facile method could fabricate single‐atom Au, Pd, Ir, and Ru supported on TiO2−H, demonstrating the generality of this strategy for the establishment of a library of SACs. Moreover, SAC exhibited versatile capacity in demethoxylation of different lignin‐derived monomers and high stability. This study showcases the superiority of atomically dispersed metal catalysts for selective demethoxylation reactions and proposes a renewable alternative to fossil‐based 4‐alkylphenols through upgrading of lignin‐derived monomers.

Catalytic Refining Lignin-Derived Monomers: Seesaw Effect between Nanoparticle and Single-Atom Pt.

Pt automatically adsorbed on oxygen vacancy of TiO2 via an in situ interfacial redox reaction, resulting in atomically dispersion of Pt on TiO2. In the upgrading of lignin-derived 4-propylguaiacol, single-atom catalyst (SAC) Pt/TiO2-H achieved a conversion of 96.9 % and a demethoxylation selectivity of 93.3 % under 3 MPa H2 at 250 °C for 3 h, markedly different from the performance of nanoparticle counterpart that gave deep deoxygenation selectivity over 99.0 %. The high demethoxylation activity of SAC Pt/TiO2-H is mainly attributed to its weak hydrogen spillover capacity that suppressed the benzene ring hydrogenation and the deep deoxygenation. Additionally, SAC Pt/TiO2-H reduced the energy barrier of CAr-OCH3 bond cleavage and accordingly lowered the Gibbs free energy of the demethoxylation reaction. This facile method could fabricate single-atom Au, Pd, Ir, and Ru supported on TiO2-H, demonstrating the generality of this strategy for the establishment of a library of SACs. Moreover, SAC exhibited versatile capacity in demethoxylation of different lignin-derived monomers and high stability. This study showcases the superiority of atomically dispersed metal catalysts for selective demethoxylation reactions and proposes a renewable alternative to fossil-based 4-alkylphenols through upgrading of lignin-derived monomers.

The application of poly(dimethyldiallylammonium chloride) in poly(butylene adipate‐co‐terephthalate)/starch composites

AbstractAntimicrobial degradable materials are pivotal in enhancing food safety, mitigating plastic pollution, and advancing sustainable development. In this study, poly(diallyldimethylammonium chloride) (PDMDAAC) was initially anchored to the starch surface (PMS) and utilized as a filler. Subsequently, poly(butylene adipate‐co‐terephthalate) (PBAT)/PMS composites with antimicrobial properties were successfully prepared by melt blending. The results showed that the introduction of PMS filler can improve the mechanical and antimicrobial properties of PBAT. Compared with pure PBAT, the tensile strength and modulus of PBAT/10PMS composites were enhanced by 25% and 29%, respectively. In addition, the prepared PBAT/PMS composites exhibited excellent antimicrobial activity against Escherichia coli when the PMS filler content reached 10 wt% or even higher. Therefore, an antimicrobial biodegradable composite was successfully prepared using a facile blending method in this study.

Synthesis and characterization of chromium aluminum carbide MAX phases (CrxAlCx-1) for potential biomedical applications.

MAX phases, characterized as nanolaminates of ternary carbides/nitrides structure, possess a unique combination of ceramic and metallic properties, rendering them pivotal in materials research. In this study, chromium aluminum carbide ternary compounds, Cr2AlC (211), Cr3AlC2 (312), and Cr4AlC3 (413) were successfully synthesized with high purity using a facile and cost-effective sol-gel method. Structural, morphological, and chemical characterization of the synthesized phases was conducted to understand the effects of composition changes and explore potential applications. Comprehensive characterization techniques including XRD for crystalline structure elucidations, SEM for morphological analysis, EDX for chemical composition, Raman spectroscopy for elucidation of vibrational modes, XPS to analyze elemental composition and surface chemistry, and FTIR spectroscopy to ensure the functional groups analysis, were performed. X-ray diffraction analysis indicated the high purity of the synthesized Cr2AlC phase as well as other ternary compounds Cr3AlC2 and Cr4AlC3, suggesting its suitability as a precursor for MXenes production. Additionally, the antimicrobial activity against Candida albicans and biocompatibility assessments against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and HepG2 cell line were investigated. The results demonstrated significant antifungal activity of the synthesized phases against Candida albicans and negligible impact on the viability of E. coli and S. aureus. Interestingly, lower concentrations of Cr2AlC MAX phase induced cytotoxicity in HepG2 cells by triggering intercellular oxidative stress, while Cr3AlC2 and Cr4AlC3 exhibited lower cytotoxicity compared to Cr2AlC, highlighting their potential in biomedical applications.

Bio-Skin-Inspired Flexible Pressure Sensor Based on Carbonized Cotton Fabric for Human Activity Monitoring.

With the development of technology, people's demand for pressure sensors with high sensitivity and a wide working range is increasing. An effective way to achieve this goal is simulating human skin. Herein, we propose a facile, low-cost, and reproducible method for preparing a skin-like multi-layer flexible pressure sensor (MFPS) device with high sensitivity (5.51 kPa-1 from 0 to 30 kPa) and wide working pressure range (0-200 kPa) by assembling carbonized fabrics and micro-wrinkle-structured Ag@rGO electrodes layer by layer. In addition, the highly imitated skin structure also provides the device with an extremely short response time (60/90 ms) and stable durability (over 3000 cycles). Importantly, we integrated multiple sensor devices into gloves to monitor finger movements and behaviors. In summary, the skin-like MFPS device has significant potential for real-time monitoring of human activities in the field of flexible wearable electronics and human-machine interaction.

Simple and facile synthesis of a CuS film using a copper formate–thioacetamide complex ink

In this study, we developed a simple and facile synthesis method for producing CuS films at low temperatures. The method uses self-reducible complex inks comprising copper formate (Cuf) as the copper source and thioacetamide (TA) as both the sulfur source and complexing agent. The thermal properties of complex inks with different TA/Cuf ratios (0.5–2.0) were analyzed. The ink with a TA/Cuf ratio of 1 exhibited a significant decrease in the reduction temperature. The synthesis of a CuS film involved calcination of the ink at 140 °C; however, some residual Cuf was observed. Introducing hexanol to the ink, aimed at prolonging the liquid-phase reaction, yielded a pure CuS film that contained agglomerated particles. The thermal reduction pathway of Cuf to CuS was analyzed through thermogravimetric–mass spectrometric analysis, and the results revealed that the low-temperature synthesis was attributed to the formation of acetonitrile and formic acid during thermal decomposition of the ink.

Effective Photogeneration of Singlet Oxygen and High Photocatalytic and Antibacterial Activities of Porous Mn-Doped ZnO-ZrO<sub>2</sub> Nanocomposites

Disperse porous Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites were prepared using the facile polymer-salt method. The effect of Mn content on the crystal structure, composite morphologies, their ability to photogenate the singlet oxygen, luminescence properties, and bactericidal activities were studied. The crystal structure and morphology of these materials were investigated using XRD and SEM analysis. It was found that obtained nanocomposites consist of small (~9 nm) hexagonal ZnO and fine ZrO<sub>2</sub> crystals and the embedding of Mn ions expands the crystal cells of ZnO crystals. Photoluminescence spectra indicate the presence of different structural defects (interstitial Zn ions and oxygen vacancies in ZnO and oxygen vacancies in ZrO<sub>2</sub> crystals). Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites can photogenerate singlet oxygen under visible (λ = 405 nm) irradiation. The increased power density of the exciting blue (λ = 405 nm) light significantly enhances the singlet oxygen photogeneration by prepared composites. The dependence of the intensity of singlet oxygen photogeneration by composites on the power density of exciting radiation (at its variation in the range 0.8 ÷ 1.6 W/cm<sup>2</sup>) is close to linear. Mn-doped ZnO-ZrO<sub>2</sub> composites demonstrate superior antibacterial activity against the gram-positive bacteria <em>Staphylococcus aureus ATCC 209P</em>. It was found that highly dispersed porous Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites are promising for practical environmental and medical applications.

All-in-One: Plasmonic Janus Heterostructures for Efficient Cooperative Photoredox Catalysis.

Janus heterostructures consisting of multiple jointed components with distinct properties have gained growing interest in the photoredox catalytic field. Herein, we have developed a facile low-temperature method to gain anisotropic one-dimensional Au-tipped CdS (Au-CdS) nanorods (NRs), followed by assembling Ru molecular co-catalyst (RuN5) onto the surface of the NRs. The CdS NRs decorated with plasmonic Au nanoparticles (NPs) and RuN5 complex harness the virtues of metal-semiconductor and inorganic-organic interface, giving directional charge transfer channels, spatially separated reaction sites, and enhanced local electric field distribution. As a result, the Au-CdS-RuN5 can act as an efficient dual-function photocatalyst for simultaneous H2 evolution and valorization of biomass-derived alcohols. Benefiting from the interfacial charge decoupling and selective chemical bond activation, the optimal all-in-one Au-CdS-RuN5 heterostructure shows greatly enhanced photoactivity and selectivity as compared to bare CdS NRs, along with a remarkable apparent quantum yield of 40.2% at 400 nm. The structural evolution and working mechanism of the heterostructures are systematically analyzed based on experimental and computational results.

The Application of Tannic Acid-Coated Magnetite Nanoparticles for Recovery of Microplastics from the Water System

The presence of microplastics (MPs) is rapidly increasing in the environment, posing a significant threat to public health and the ecosystem. To monitor the impact of MPs, it is crucial to have standardized detection methods and MPs remediation techniques. Therefore, this study aimed to use tannic acid-coated magnetite nanoparticles to recover MPs, specifically polystyrene (PS) and polyethylene terephthalate (PET), from water bodies. A facile method for MPs recovery was established using the synthesized tannic acid-coated magnetite (TA-Fe3O4) as an adsorbent. TA-Fe3O4 was synthesized using tannic acid, iron (II) sulfate heptahydrate, and iron (III) chloride hexahydrate through a one-pot co-precipitation method. The adsorbent material was then characterized using a scanning electron microscope coupled with an energy dispersive x-ray spectroscopy (SEM–EDS), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, zeta potential, and N2 adsorption–desorption (BET) techniques, confirming its successful synthesis. The maximum adsorption efficiencies for PS and PET were 83% and 98%, respectively, under the experimental conditions of pH 6–7, a contact time of 300 min, an adsorbent dose of 2.5 g/L, and an initial MPs concentration of 1.25 g/L. The study also found that the presence of ions in wastewater had a significant effect on MP recovery. However, when it came to recovering MPs from the spent adsorbent, the maximum values were observed in an acidic medium at pH 3–4 under sonification conditions. In conclusion, TA-Fe3O4 showed potential and efficiency in the recovery of MPs in aqueous media. However, further investigation is needed to improve the method and explore its application for multi-MPs recovery performance.

Rational Design of Liquid-Liquid Microdispersion Droplet Microreactors for the Controllable Synthesis of Highly Uniform and Monodispersed Dextran Microspheres.

Hydrogel microspheres are biocompatible materials widely used in biological and medical fields. Emulsification and stirring are the commonly used methods to prepare hydrogels. However, the size distribution is considerably wide, the monodispersity and the mechanical intensity are poor, and the stable operation conditions are comparatively narrow to meet some sophisticated applications. In this paper, a T-shaped stepwise microchannel combined with a simple side microchannel structure is developed to explore the liquid-liquid dispersion mechanism, interfacial evolution behavior, satellite droplet formation mechanism and separation, and the eventual successful synthesis of dextran hydrogel microspheres. The effect of the operation parameters on droplet and microsphere size is comprehensively studied. The flow pattern and the stable operation condition range are given, and mathematical prediction models are developed under three different flow regimes for droplet size prediction. Based on the stable operating conditions, a microdroplet-based method combined with UV light curing is developed to synthesize the dextran hydrogel microsphere. The highly uniform and monodispersed dextran microspheres with good mechanical intensity are synthesized in the developed microfluidic platform. The size of the microsphere could be tuned from 50 to 300 μm with a capillary number in the range of 0.006-0.742. This work not only provides a facile method for functional polymeric microsphere preparation but also offers important design guidelines for the development of a robust microreactor.

Fabrication of versatile Fe3O4/GO/Au composite nanomaterial as SERS-active substrate for detection of pesticide residue.

Highly active Fe3O4/GO/Au composite nanomaterial was fabricated as a substrate of surface-enhanced Raman spectroscopy (SERS) and applied for pesticide residue detection. The three-layer multifunctional Fe3O4/GO/Au nanoparticles (NPs) were designed by facile method, with high hotspots, and were characterized by various techniques, including ultraviolet spectrophotometry (UV), X-ray diffraction (XRD), infrared absorption spectrometer (IR), and transmission electron microscopy (TEM). The performance of Fe3O4/GO/Au was evaluated by Raman spectroscopy with R6G as a probe molecule to verify its enhancement effect. It exhibited a strong Raman signal with 10-6M of R6G. Furthermore, the presence of Fe3O4/GO/Au nanohybrid enabled the SERS-based method to detect mancozeb and showed an excellent linear relationship in the range of 0.25-25 ppm, with a low limit of detection (0.077 ppm), satisfactory EF, stability, and repeatability. In addition, the mechanism of SERS enhancement with electromagnetic mechanism (EM) and chemical mechanism (CM) was discussed in detail. Therefore, the proposed SERS approach holds promise as an auxiliary technique for screening contaminated agricultural products, environmental sample, and food in the future.