Boosting oxygen evolution reaction rates with mesoporous Fe-doped MoCo-phosphide nanosheets.

Transition metal-based catalysts are commonly used for water electrolysis and cost-effective hydrogen fuel production due to their exceptional electrochemical performance, particularly in enhancing the efficiency of the oxygen evolution reaction (OER) at the anode. In this study, a novel approach was developed for the preparation of catalysts with abundant active sites and defects. The MoCoFe-phosphide catalyst nanosheets were synthesized using a simple one-step hydrothermal reaction and chemical vapor deposition-based phosphorization. The resulting MoCoFe-phosphide catalyst nanosheets displayed excellent electrical conductivity and a high number of electrochemically active sites, leading to high electrocatalytic activities and efficient kinetics for the OER. The MoCoFe-phosphide catalyst nanosheets demonstrated remarkable catalytic activity, achieving a low overpotential of only 250 mV to achieve the OER at a current density of 10 mA cm-2. The catalyst also exhibited a low Tafel slope of 43.38 mV dec-1 and maintained high stability for OER in alkaline media, surpassing the performance of most other transition metal-based electrocatalysts. The outstanding OER performance can be attributed to the effects of Mo and Fe, which modulate the electronic properties and structures of CoP. The results showed a surface with abundant defects and active sites with a higher proportion of Co2+ active sites, a larger specific surface area, and improved interfacial charge transfer. X-ray photoelectron spectroscopy (XPS) analysis revealed that the catalyst's high activity originates from the presence of Mo6+/Mo4+ and Co2+/Co3+ redox couples, as well as the formation of active metal (oxy)hydroxide species on its surface.

Magnetically separable Co0.6Fe2.4O4/MIL-101-NH2 adsorbent for Congo red efficient removal.

The development of effective and practical adsorbents for eliminating pollutants still remains a significant challenge. Herein, we synthesized a novel magnetically separable composite, Co0.6Fe2.4O4/MIL-101-NH2, through the in-situ growth of MIL-101-NH2 on magnetic nanoparticles, designed specifically for the removal of Congo red (CR) from aqueous solutions. MIL-101-NH2 possessed high BET surface area (240.485 m2•g-1) and facile magnetic separation function and can be swiftly separated (within 30 s) through an external magnetic field post-adsorption. The investigation systematically explored the influence of crucial parameters, including adsorbent dosage, pH, adsorption duration, temperature, and the presence of interfering ions, on CR adsorption performance. Findings indicate that CR adsorption adheres to the pseudo-second-order (PSO) kinetic model and the Langmuir isotherm model. Thermodynamic analysis reveals the spontaneity, endothermic nature, and orderly progression of the adsorption process. Remarkably, the adsorbent with 0.1 g•L-1 boasts an impressive maximum adsorption capacity of 1756.19 mg•g-1 for CR at 298.15 K, establishing its competitive advantage. The reuse of the adsorbent over 5 cycles remains 78% of the initial adsorption. The CR adsorption mechanisms were elucidated, emphasizing the roles of π-π interactions, electrostatic forces, hydrogen bonding, and metal coordination. Comparison with other dyes, such as methylene blue (MB) and methyl orange (MO), and exploration of adsorption performance in binary dye systems, demonstrates the superior capacity and selectivity of this adsorbent for CR. In conclusion, our magnetically separable metal-organic framework (MOF)based composite presents a versatile and effective solution for CR removal, with promising applications in water treatment and environmental remediation.

A cooling-driven self-adaptive and removable hydrogel coupled with combined chemo-photothermal sterilization for promoting infected wound healing.

Hydrogel dressings that can fit irregular wounds, promote wound healing, and detach from wounds without damage represent the development trend of modern medical dressings. Herein, a novel composite hydrogel with excellent wound shape matching and painless removability via a gel-sol phase transition is constructed through dynamic borate ester bonds between phenylboronic acid-grafted F127 (PF127) and polydopamine-coated reduced graphene oxide/silver nanoparticles (rGO@PDA/Ag NPs). After contact with the skin tissues, the administered liquid-like sols gradually transform into solid-like gels, robustly adhering to the wound. The hydrogel dressings containing near-infrared (NIR)-responsive rGO@PDA and in situ formed Ag NPs can generate localized heat and gradually release Ag+ to realize safe, effective, and durable photothermal-chemical combined sterilization. In addition, catechol-rich PDA endows the hydrogel dressings with good antioxidant activity and adhesiveness. In vivo study results indicate that the hydrogel dressings can significantly accelerate full-thickness skin infected wound healing by eliminating bacteria, promoting collagen deposition and angiogenesis, as well as reducing inflammation. Collectively, the thermoreversible rGO@PDA/Ag-PF127 hydrogel dressings with an improved self-adapting ability, superior antimicrobial activity, and tunable adhesion appear to be a promising candidate for the treatment of infected wounds.

Highly TVB-N sensitive film with CMS as the 'bridge' via electrostatic interaction and hydrogen bond self-assembly for monitoring food freshness in intelligent packaging.

This work aims to develop the novel TVB-N sensitive film for monitoring food freshness. The film was fabricated based on carboxymethyl starch sodium (CMS)/agar (AG) complex and natural pigment, red radish anthocyanins (RRA). However, RRA is highly unstable under high humid conditions for their hydrophily. To immobilize RRA in AG film, we brought up CMS (negative charge) to immobilize RRA (positive charge) via electrostatic attractions and combined CMS and AG via hydrogen bond self-assembly. Zeta potential, Fourier transforms infrared (FT-IR) spectra, and X-ray diffraction analysis proved the electrostatic interaction and hydrogen bond self-assembly effect, indicating RRA immobilized effectively. Migration evaluation displayed that RRA remained stable in a high humidity environment (from RH 35%-95%). And its color difference is less than 5% in the low-temperature environment (4 °C). The prepared sensing film was found to be applied to detect the freshness of packaged grass carp and shrimp products. Its colors changed from initial orange-red to light red (3rd day) and then purple (4th day) with the increase of volatile amines inside the packaging. These findings suggested the film can be used as a sensing device for intelligent packaging of protein-rich food.

An Fe-doped Co-oxide electrocatalyst synthesized through a post-modification method toward advanced water oxidation.

In the context of the ever-increasing energy crisis, electrocatalytic water splitting has attracted widespread attention as an effective means to provide clean energy. However, the oxygen evolution reaction (OER), which is an important anodic half reaction, shows very slow kinetics due to the multi-step electron transfer process, which severely restricts the efficiency of energy conversion. Herein, we used a simple solvothermal method to dope iron into the cobalt-containing hydroxide precursor, and successfully prepared the Fe-doped Co-oxide electrocatalyst Co3-xFexO4-0.01. It only needs an overpotential of 294 mV to perform the OER at a current density of 10 mA cm-2, and has a low Tafel slope of 47.3 mV dec-1. Moreover, Co3-xFexO4-0.01 has excellent stability. There is no significant increase in the overpotential for oxygen evolution at a current density of 10 mA cm-2 after nearly 20 h. BET surface area test and XPS spectroscopy results show that Fe doping provides more mesopores and oxygen bridges, which is conducive to the construction of active sites and electronic regulation during the OER. This work can help design more bimetallic based highly active OER materials.

Fabrication of a "progress bar" colorimetric strip sensor array by dye-mixing method as a potential food freshness indicator.

Colorimetric sensing is a low-cost, intuitive method for monitoring the freshness of food. We prepared a colorimetric strip sensor array by mixing different amounts of bromophenol blue (BPB) and bromocresol green (BCG). As results of NH3 simulation, the array strip turned from yellow to blue, and the number of blue spots increased with the increasing NH3, like a progress bar. Although the actual color is quite different, the color-changing trend was consistent with the simulated model calculated by a computer. The progress bar results remained stable under three lighting conditions. Furthermore, in the Cod preservation experiment, the color-changing progress of the strip sensor array is consistent with the simulation and can indicate Cod freshness while providing more distinguish levels. Therefore, a "progress bar" indicator built by this strategy possess the potential of realizing nondestructive, more accurate, and commercially available food quality monitoring through the naked eye and smart equipment recognition.

Recent advances in chitosan-based layer-by-layer biomaterials and their biomedical applications.

In recent years, chitosan-based biomaterials have been continually and extensively researched by using layer-by-layer (LBL) assembly, due to their potentials in biomedicine. Various chitosan-based LBL materials have been newly developed and applied in different areas along with the development of technologies. This work reviews the recent advances of chitosan-based biomaterials produced by LBL assembly. Driving forces of LBL, for example electrostatic interactions, hydrogen bond as well as Schiff base linkage have been discussed. Various forms of chitosan-based LBL materials such as films/coatings, capsules and fibers have been reviewed. The applications of these biomaterials in the field of antimicrobial applications, drug delivery, wound dressings and tissue engineering have been comprehensively reviewed.

Color-switchable hybrid dots/hydroxyethyl cellulose ink for anti-counterfeiting applications.

Many anti-counterfeiting inks have been explored recently, most of them are commonly involved in weak fastness, high cost and long-term toxicity, impeding their real-life applications. Herein, an environment-friendly and inexpensive anti-counterfeiting ink with excellent fastness is reported. The untifake ink is developed by combining hybrid dots (silicon/carbon) with hydroxyethyl cellulose (HEC) binder. Interestingly, the HEC binder can effectively prevent from aggregation-induced quenching of hybrid dots. Subsequently, the customized patterns are successfully transferred onto different surfaces of various substrates including cotton fabric, cellulosic paper, glass, metal, silicon wafer and PET film, using the as-prepared ink by screen-printing technique, exhibiting that the hybrid dots/HEC ink possesses widespread practicability. Notably, fluorescent color of these patterns can be switchable by adjusting environmental pH-value, further imparting the as-prepared ink with excellent covert performance. This new fluorescent hybrid dots/HEC ink will be promising candidates for high-level anti-counterfeiting applications including food packaging, apparel and documents.

Preparation of 1, 3, 6, 8-Pyrenesulfonic Acid Tetrasodium Salt Dye-Doped Silica Nanoparticles and Their Application in Water-Based Anti-Counterfeit Ink.

In order to improve the luminescent stability of water-based anti-counterfeit ink, a new fluorescent material is prepared by doping dye into silica nanoparticles. Water soluble anionic dye 1, 3, 6, 8-pyrenesulfonic acid sodium salt (PTSA) is selected as the dopant. In this work, PTSA is successfully trapped into silica nanoparticles (SiNPs) by the reverse microemulsion method using cationic polyelectrolyte poly (dimethyl diallyl ammonium chloride; PDADMAC) as a bridge. The UV absorption spectra, fluorescence emission spectra and fluorescent decay curves are used to describe the luminescent properties of the PTSA-doped silica nanoparticles (PTSA-SiNPs). In addition, the as-prepared PTSA-SiNPs and polyurethane waterborne emulsion are used to prepare water-based anti-counterfeit ink, and fluorescent patterns are successfully printed through screen-printing. The samples printed by the ink exhibit desirable fluorescence properties, heat stability, robust photostability, and a fluorescent anti-counterfeit effect, which makes the PTSA-SiNPs promising luminescent materials for anti-counterfeit applications.

Electrodeposition of Polysaccharide and Protein Hydrogels for Biomedical Applications.

In the last few decades, polysaccharide and protein hydrogels have attracted significant attentions and been applied in various engineering fields. Polysaccharide and protein hydrogels with appealing physical and biological features have been produced to meet different biomedical applications for their excellent properties related to biodegradability, biocompatibility, nontoxicity, and stimuli responsiveness. Numerous methods, such as chemical crosslinking, photo crosslinking, graft polymerization, hydrophobic interaction, polyelectrolyte complexation and electrodeposition have been employed to prepare polysaccharide and protein hydrogels. Electrodeposition is a facile way to produce different polysaccharide and protein hydrogels with the advantages of temporal and spatial controllability. This paper reviews the recent progress in the electrodeposition of different polysaccharide and protein hydrogels. The strategies of pH induced assembly, Ca2+ crosslinking, metal ions induced assembly, oxidation induced assembly derived from electrochemical methods were discussed. Pure, binary blend and ternary blend polysaccharide and protein hydrogels with multiple functionalities prepared by electrodeposition were summarized. In addition, we have reviewed the applications of these hydrogels in drug delivery, tissue engineering and wound dressing.

Processing and Characterization of Polymer-Based Far-Infrared Composite Materials.

Polymer-based far-infrared radiation (FIR) composite materials are receiving increasing attention due to their significant influence on bioactivity. This study reports the processing of FIR composite films based on a polymer matrix and FIR radiation ceramic powders, as well as the characterization of the FIR composites. Field-emission scanning electron microscopy (SEM) and laser particle size analysis were employed to analyze the characteristic of the ceramic powders. The average size, dispersity, and specific surface area of the ceramic powders were 2602 nm, 0.97961, and 0.76 m2/g, respectively. The results show that the FIR ceramic powders used in the composite films had excellent far-infrared emissive performance. Moreover, by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), it was indicated that the thermal performance and mechanical properties of the composite films were significantly influenced (p < 0.05) by the addition of the FIR ceramic powders. Specifically, the elongation at break decreased from 333 mm to 201 mm with the increase in FIR ceramic powders. Meanwhile, the contact angle and light transmittance were also changed by the addition of the FIR ceramic powders. Furthermore, the two different processing methods had great influence on the properties of the composite films. Moreover, the composite blown films with 1.5% FIR ceramic powders showed the highest far-infrared emissivity, which was 0.924.

Application of Response Surface Methodology for Improving the Yield of 1,5-bis(ptoluenesulfonyl)- 3,7-Dihydroxyoctahydro-1,5-Diazocine.

BACKGROUND: 3,3,7,7-tetrakis (difluoramino) octahydro-1,5-dinitro-1,5-diazocine (HNFX), as an important oxidizer in propellants, has received much attention due to its high density and energy. However, there are many difficulties that need to be solved, such as complex synthetic processes, low product yield, high cost of raw materials and complicated purification. In the synthesis of HNFX, the intermediate named 1,5-bis (p-toluenesulfonyl)-3,7-dihydroxyoctahydro-1, 5-diazocine (gem-diol), is difficult to synthesize. METHODS: A simple method was used to synthesize the gem-diol. This prepared gem-diol was characterized by FT-IR, 1H NMR, melting point and mass spectrometry. In order to increase the yield of gem-diol, response surface methodology (RSM) was introduced to optimize experimental conditions. RESULTS: After the establishment of the model, the optimal conditions of synthesis were found to be 9.33h for reaction time, 6.13wt. % for the concentration of NaOH and 1.38:1 for ratio of ECH (p-toluenesulfonamide): TCA (epichlorohydrin). Under the optimal conditions, the experimental value and the predicted value of yield were 22.18% and 22.92%, respectively. CONCLUSION: 1,5-bis (p-toluenesulfonyl)-3,7-dihydroxyoctahydro-1,5-diazocine (gem-diol) can be synthesized using the low cost of chemical materials, including p-toluenesulfonamide, epichlorohydrin, sodium hydroxide and ethanol. Response surface methodology (RSM) is an effective method to optimize the synthesis process, thereby improving the yield of gem-diol.

Titanium Dioxide Nanotube-Based Oxygen Indicator for Modified Atmosphere Packaging: Efficiency and Accuracy.

Colorimetric oxygen indicators can be applied for non-destructive testing in packaging; especially in modified atmosphere packaging (MAP). In this paper; titanium dioxide (TiO2) nanotube; which is used as a semiconductor photocatalyst in oxygen indicators; was synthesized via a microwave-assisted hydrothermal method. X-Ray Diffraction (XRD) was used to analyze its crystal form and Scanning Electron Microscope (SEM).to characterize its morphology. Its properties were studied using Brunauer-Emmett-Teller (BET), Diffuse Reflection Spectrum (DRS), and Bluebottle experiments. The results showed that the synthesized TiO2 nanotube was a mixture of rutile and anatase; with a specific surface area of 190.35 m²/g; and a wide band gap of 3.34 eV. Given the satisfactory performance; the TiO2-based oxygen indicator was prepared and combined with glycerol; methylene blue; and hydroxyethyl cellulose (HEC). The oxygen indicator demonstrated excellent photocatalytic performance and effectively avoided excitation by visible light. We studied the rheological properties; thixotropic properties; and wettability of the indicator. The results demonstrated the printability of the indicator solution; which was then printed in the polyethylene terephthalate (PET) film by screen printing and applied to MAP. The application results showed that the prepared oxygen indicator was able to provide visual support to judge whether the packaging was intact and the food was safe.

A facile synthesis of 1,3,6,8-pyrenesulfonic acid tetrasodium salt as a hydrosoluble fluorescent ink for anti-counterfeiting applications.

In this work, 1,3,6,8-pyrenesulfonic acid sodium salt (PTSA) was successfully synthesized via a one-step sulfonating reaction. This method is more convenient, effective and eco-friendly than the traditional one. The as-prepared PTSA exhibits pure blue fluorescence under UV light. Due to its excellent fluorescent properties and water solubility, PTSA was used to prepare water-soluble invisible inks based on hydroxyethyl cellulose (HEC) aqueous solution. Notably, the resulting inks possessed acceptable stability after being stored for 30 days. Besides, the red/green/blue fluorescent inks were obtained by adding extra pigments, all of which exhibited excellent rheology and thixotropy properties. Subsequently, various patterns, including a QR code, the logo of Wuhan University, Chinese characters and so on, were printed on non-background paper through ink-jet and screen printing, and the as-prepared materials exhibited good water solubility and outstanding fluorescence performances, indicating that the fluorescent PTSA material is a promising candidate for anti-counterfeiting applications.

Properties and Applications of High Emissivity Composite Films Based on Far-Infrared Ceramic Powder.

Polymer matrix composite materials that can emit radiation in the far-infrared region of the spectrum are receiving increasing attention due to their ability to significantly influence biological processes. This study reports on the far-infrared emissivity property of composite films based on far-infrared ceramic powder. X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray powder diffractometry were used to evaluate the physical properties of the ceramic powder. The ceramic powder was found to be rich in aluminum oxide, titanium oxide, and silicon oxide, which demonstrate high far-infrared emissivity. In addition, the micromorphology, mechanical performance, dynamic mechanical properties, and far-infrared emissivity of the composite were analyzed to evaluate their suitability for strawberry storage. The mechanical properties of the far-infrared radiation ceramic (cFIR) composite films were not significantly influenced (p ≥ 0.05) by the addition of the ceramic powder. However, the dynamic mechanical analysis (DMA) properties of the cFIR composite films, including a reduction in damping and shock absorption performance, were significant influenced by the addition of the ceramic powder. Moreover, the cFIR composite films showed high far-infrared emissivity, which has the capability of prolonging the storage life of strawberries. This research demonstrates that cFIR composite films are promising for future applications.

Novel Waterborne UV-Curable Hyperbranched Polyurethane Acrylate/Silica with Good Printability and Rheological Properties Applicable to Flexographic Ink.

Novel waterborne UV-curable hyperbranched polyurethane acrylate/silica (HBWPUA/SiO2) nanocomposites were prepared by a three-step procedure and sol-gel method. 1H NMR and 13C NMR results indicate that HBWPU is successfully synthesized. Surface tension and contact angle tests both demonstrate the good wettability of the nanocomposites. Besides, the kinetics of photopolymerization of HBWPUA/SiO2 films were analyzed by attenuated total reflection-Fourier transform infrared spectroscopy, which reveals that the modified SiO2 could accelerate the curing speed of HBWPUA coatings. Thermal gravity analysis indicates that the HBWPUA/SiO2 hybrid films have a better thermal stability than the pure HBWPUA cured films. Furthermore, the hybrid films show enhanced pencil hardness, abrasion resistance, and adhesion. On the basis of the above, HBWPUA/SiO2 nanocomposites were finally applied to waterborne UV-curing flexographic printing ink, which is printed on poly(ethylene terephthalate) and glass. The nanocomposite presents good rheological behavior because the ink has a lower Z 0, a higher Z ∞, and the viscosity rebuild time is 375 s. Three colors (red, yellow, and blue) of ink were used to test its printing quality, the curing time was below 30 s, and the adhesion was excellent without being stripped. All of the inks show good water resistance and abrasion resistance. Moreover, the red and blue inks possess better solid densities than the value of 1.07 of yellow ink, and are 1.83 and 1.84, respectively. The current study suggests that the process has promise in applications of food packages.

Interaction between chitosan-based clay nanocomposites and cellulose in a chemical pulp suspension.

Quaternized chitosan/organic montmorillonite (QCS/OMMT) nanocomposites were synthesized under microwave irradiation. XRD and TEM analyses confirmed that QCS intercalated into the interlayer of OMMT and clay layers distributed uniformly in QCS matrix. QCS/OMMT nanocomposites were used as retention and drainage-aid agents in pulp suspension, during which the interface behavior of positively charged QCS/OMMT nanocomposites on negatively charged cellulosic substrate and CaCO3 substrate was investigated. With the addition of QCS/OMMT nanocomposites, the particle size of cellulosic substrate increased, while the beating degree and the total residual carbohydrate concentration decreased. The results indicated that QCS/OMMT nanocomposite made a difference in paper making process through the charge patch interaction. Moreover, QCS/OMMT nanocomposites had a strong interaction with CaCO3, which was significant in fiber fines retention and paper production. When the mass ratio of QCS to OMMT was 8:1, the QCS/OMMT nanocomposite demonstrated the strongest retention and drainage-aid effect.

Surface modification and characterization of carbon spheres by grafting polyelectrolyte brushes.

Modified carbon spheres (CSPBs) were obtained by grafting poly(diallyl dimethyl ammonium chloride) (p-DMDAAC) on the surface of carbon spheres (CSs). It can be viewed as a kind of cation spherical polyelectrolyte brushes (CSPBs), which consist of carbon spheres as core and polyelectrolytes as shell. The method of synthesizing carbon spheres was hydrothermal reaction. Before the polyelectrolyte brushes were grafted, azo initiator [4,4'-Azobis(4-cyanovaleric acyl chloride)] was attached to the carbon spheres' surface through hydroxyl groups. CSPBs were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), conductivity meter, and system zeta potential. The results showed that compared with carbon spheres, the conductivity and zeta potential on CSPBs increased from 9.98 to 49.24 µS/cm and 11.6 to 42.5 mV, respectively, after the polyelectrolyte brushes were grafted. The colloidal stability in water was enhanced, and at the same time, the average diameter of the CSPBs was found to be 173 nm, and the average molecular weight and grafted density of the grafted polyelectrolyte brushes were 780,138 g/mol and 4.026 × 10(9)/nm(2,) respectively.