Hydrothermal Synthesis Research Articles

Formation of iron-rich phyllosilicates in the FeO–SiO2–H2O system during hydrothermal synthesis as a function of pH

Abstract The formation of iron-rich phyllosilicates can occur at different natural or engineered settings. In this study, the influence of pH in the hydrothermal synthesis of iron-rich phyllosilicates was investigated in the pH range 8.50–12.10 after the ageing of the precursor. The synthesized samples were characterized by powder X-ray diffraction, Raman and Mössbauer spectroscopies and transmission electron microscopy. Three domains of pH were identified, and these correlated with silica availability and its speciation in the solution. The formation of 1:1-type FeIII/FeII phyllosilicate was observed between pH 9.67 and 10.75. Above pH 10.75, two types of phyllosilicate-like mineral phases were observed. In addition to 1:1-type FeIII/FeII phyllosilicate, 2:1-type FeIII/FeII phyllosilicate was observed. Below pH 9.67, mainly amorphous silica and iron oxides were observed. The findings show that pH governed the crystallinity and nature of the obtained phyllosilicate-like phases.

Bismuthene@ZnAlBi LDHs structure as a novel nanosorbent for efficient uptake of arsenic (V)

Two-dimensional bismuthene material is characterized with promising and superior optical, electrical and other characteristics. The application of 2D-bismuthene or its composites in water remediation of As(V) was not previously investigated. Consequently, embedded bismuthene into zinc aluminum bismuth-layered double hydroxide (ZnAlBi LDHs-embedded-Biene) was simply fabricated as a novel nanosorbent. Bismuthene (Biene) was prepared by bottom up hydrothermal reaction, while ZnAlBi LDHs was synthesized by a coprecipitation method followed by hydrothermal treatment process. Characterization of ZnAlBi LDHs-embedded-Biene referred to a crystalline mesoporous structure of globular particles with 5–8 nm. It was confirmed that the nanosorbent exterior surface is functionalized with metal oxides and metal oxyhydroxide, while exchangeable carbonate anion existed in the nanosorbent inner layer. Therefore, arsenate uptake was favored by both exterior electrostatic attraction and anion exchange processes. The highest uptake capacity of As(V) by ZnAlBi LDHs-embedded-Biene was detected at pH 3 and contact time 30 min providing 94.67% removal by using 5 mg L−1 As(V) concentration. The ionic strength factor proved a good selectivity of the nanosorbent toward As(V) ions. Thermodynamic behavior of interaction between As(V) and nanosorbent was emphasized as exothermic and spontaneous process, while the kinetic evaluation indicated that the pseudo-second order was the best-fitting expression. The application of ZnAlBi LDHs-embedded-Biene in the adsorptive uptake process of As(V) ions from various water samples referred to elevated uptake percentages as 93.29% and 90.52% by 5 mg L−1 and 10 mg L−1 As(V), respectively. The adsorbed As(V) onto ZnAlBi LDHs-embedded-Biene exhibited excellent recyclability and re-usage up to five cycles to affirm that the designed ZnAlBi LDHs-embedded-Biene has a great prospect for utilization in water purification from As(V).

Effect of carbon quantum dots’ surface functional groups on tribological performance of polyethylene glycol

Nano additives play an important role in improving the lubricating properties and enhancing the bearing capacity of lubricants. However, traditional nano-additives contain harmful elements such as heavy metals, sulfur, phosphorus, which have a non-negligible impact on the green production of modern industry. In this study, four kinds of carbon quantum dots (CQDs) were prepared by hydrothermal synthesis method, namely CQDs, amino modified CQDs (CQDs-NH2), alkyl modified CQDs (CQDs-CH3), and hydroxyl modified CQDs (CQDs-OH). The microscopic morphology, chemical structure and luminescence of CQDs were characterized. The effects of four kinds of CQDs additives on the tribological properties of polyethylene glycol (PEG) were studied. The results showed that compared with PEG, the average friction coefficient and wear volume of PEG containing 3% CQDs-OH decreased by 60.50% and 95.05%, respectively. A composite protective film containing carbon, nitrogen, FeO, Fe2O3 forms on the worn surface, due to the end hydroxyl group of CQDs-OH has good adsorption. In addition, after 3 months of dispersion experiment, the PEG containing 3% CQDs-OH showed the best dispersion stability, and the antifriction effect was still better than that of pure PEG. Therefore, CQDs-OH is a new type of environmentally friendly lubricating additive with great potential.

Water-Tolerant Superbase Polyoxometalate [H2(Nb6O19)]6- for Homogeneous Catalysis.

Here, doubly protonated Lindqvist-type niobium oxide cluster [H2(Nb6O19)]6-, fabricated by microwave-assisted hydrothermal synthesis, exhibited superbase catalysis for Knoevenagel and crossed aldol condensation reactions accompanied by activating C-H bond with pKa >26 and proton abstraction from a base indicator with pKa=26.5. Surprisingly, [H2(Nb6O19)]6- exhibited water-tolerant superbase properties for Knoevenagel and crossed aldol condensation reactions in the presence of water, although it is well known that the strong basicity of metal oxides and organic superbase is typically lost by the adsorption of water. Density functional theory calculation revealed that the basic surface oxygens that share the corner of NbO6 units in [H2(Nb6O19)]8- maintained the negative charges even after proton adsorption. This proton capacity and the presence of un-protonated basic sites led to the water tolerance of the superbase catalysis.

Combined Potential of Quarry Waste Fines and Eggshells for the Hydrothermal Synthesis of Tobermorite at Varying Cement Content

Quarry waste fines and eggshells are unavoidable wastes which relentlessly contribute to environmental loads and pollution. Although many studies have suggested various methods for recycling, these wastes remain underutilized due to some technical constraints. In addition, no study has yet explored the possibility of combining quarry waste fines (QWF) and eggshell powder (ESP) for tobermorite synthesis. Tobermorite is the main component which primarily provides strength to autoclaved aerated concrete products. With this in mind, this study seeks to evaluate the potential of QWF-ESP mix at 10%, 15%, and 20% amounts of cement, respectively. The XRF, XRD, and TGA–DTA techniques were used to characterize the waste materials, while physical and mechanical property tests and XRD analysis were performed on the autoclaved samples. It was found that QWF contains 53.77% SiO2 and ESP contains 97.8% CaO which are key components for tobermorite synthesis. This study also revealed that the mixture with only 10% cement has the highest compressive strength among the QWF-ESP samples. Furthermore, the formation of tobermorite in the samples was confirmed through XRD analysis. Hence, the hydrothermal curing of QWF-ESP can be further developed to produce functional tobermorite-bearing materials.

Enhancing Bone Implants: Magnesium-Doped Hydroxyapatite for Stronger, Bioactive, and Biocompatible Applications.

Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is an inorganic material that exhibits morphology and composition similar to those of human bone tissues, making it highly desirable for bone regeneration applications. As one of the most biocompatible materials currently in use, HAp has undergone numerous attempts to enhance its mechanical strength. This research focuses on investigating the influence of magnesium (Mg) incorporation on the structural and mechanical properties of synthesized magnesium-doped hydroxyapatite (MgHAp) samples. Apart from its biocompatibility, Mg possesses a density and elasticity comparable to those of human bone. Therefore, incorporating Mg into HAp can be pivotal for improving bone formation. Previous studies have not extensively explored the structural changes induced by Mg substitution in HAp, which motivated us to revisit this issue. Hydrothermal synthesis technique was used to synthesize MgHAp samples with varying molar concentrations (x = 0, 0.5, 1.0, and 1.5). Theoretical simulation of HAp and MgHAp for obtaining 3D structures has been done, and theoretical X-ray diffraction (XRD) data have been compared with the experimental XRD data. Rietveld analysis revealed the alteration and deviation of lattice parameters with an increase in the Mg content, which ultimately affect the structure as well the mechanical properties of prepared samples. The findings revealed an increase in compressive stress and fracture toughness as the Mg concentration in the composition increased. Furthermore, using a finite-element analysis technique and modeling of the mechanical testing data, the von Mises stress distribution and Young's modulus values were calculated, demonstrating the similarity of the prepared samples to human cortical bone. Biocompatibility assessments using NIH-3T3 fibroblast cells confirmed the biocompatible and bioactive nature of the synthesized samples. MgHAp exhibits great potential for biomedical applications in the dental, orthopedic, and tissue engineering research fields.

Mechanical and thermal response of XFe2O4 (X = Zn, Ag and Co) spinel ferrites via IR-spectroscopy and first-principles calculations

The lack of comprehensive literature on the all-important aspect of the elasticity of spinel ferrites led to the hydrothermal synthesis of different (Co, Zn, Ag) spinel ferrites. IR spectroscopy revealed the characteristic absorption bands of metal-oxygen in all three compositions. The shifting of tetrahedral and octahedral bending vibrations towards higher frequencies owes to changes in inter-atomic and inter-ionic distances. Elastic parameters, wave velocities, and Debye temperature have been calculated using IR spectroscopy data. Elastic parameters have been higher for Co ferrites than Zn and Ag ferrites. The Poisson ratio seems to be consistent for different spinel ferrites. Shear wave velocity has been found to be higher than longitudinal wave velocity because perpendicular particle vibrations take higher energy than parallel vibrations. Wave velocities have been found to be higher in Ag ferrites than in the other two compositions. Debye temperature follows the same trend as elastic parameters. Additionally, we have confirmed the mechanical stability of the Co, Zn, and Ag ferrites using the first-principles calculations in the density functional theory (DFT) approach framework. Interestingly, the Co/Zn/Ag ferrites exhibit semiconducting nature with a band gap of 3.96/3.66/0.71 ev. Our study could pave the way for next-generation spintronic devices.

Fluorescent Carbonized Polymer Dots Derived from o-phenylenediamine and its Photonic Application.

Optimizing the optoelectronic characteristics of low-dimensional carbon dots (CDs) through surface modifications and doping has proven instrumental in tailoring them for diverse applications. This study explores a facile and economical hydrothermal synthesis method for generating Carbonized Polymer Dots using o-phenylenediamine at different temperatures. The resulting materials exhibit structural and morphological variations linked to the synthesis temperature. A transition from carbon dots (CDs) embedded in reduced graphene oxide (rGO)-like sheet structures at low temperatures to the core-shell structure at the highest temperature is observed in HR-TEM, implying the formation of CPDs. X-ray photoelectron spectroscopy (XPS) corroborates these findings, showing an augmented degree of graphitization in alignment with HR-TEM results. The photoluminescence spectra of CPDs synthesized at the lowest temperature exhibit multiple emission peaks, resulting in a yellowish-orange color. Utilizing these CPDs to fabricate light-emitting diodes (LEDs) produces a vivid bright-green emission with CIE coordinates (0.378, 0.522). Moreover, the CPDs demonstrate solvatochromism across diverse solvents of varying polarity, covering the entire visible spectrum. This intriguing solvatochromic effect positions the CPDs as promising materials for polarity probing applications.

Impurities in Polymer-Lined Autoclaves Affect Zeolite Synthesis and Si Incorporation Behavior.

Polymer-lined autoclaves are commonly believed to be highly durable and inert in hydrothermal reactions. Herein, we use the hydrothermal synthesis of AlPO-18 zeolite as a case study to demonstrate that the choice of autoclave materials (polytetrafluoroethylene or para-polyphenylene) does significantly affect the product of zeolite synthesis. A small amount of glass fiber in the PPL-lined autoclave unexpectedly functions as a source of silicon and yields SAPO-34 instead of AlPO-18 as the product. The outcomes of 19 successive experiments conducted with a single PPL-lined autoclave exhibit significant variations, further highlighting that the impurities arising from the autoclaves should be considered during the hydrothermal synthesis procedure. In contrast to SAPO-34 synthesized by the conventional method, which displays only Si(4Al) at a low Si/Al ratio, SAPO-34 synthesized in the PPL-lined autoclave exhibits multiple silicon coordination environments. This outcome provides new physical insights into the silicon incorporation mechanism and proposes a viable strategy for regulating the silicon coordination environment at low Si/Al ratios.

Commercial Wheat and Oat Flour Derived Fluorescent Carbon Quantum Dots through Sustainable Hydrothermal Synthesis and Their Biological Activities

AbstractIn this study, we utilized processed edible commercial wheat and oat flours to synthesize highly fluorescent carbon dots using green hydrothermal synthesis. The as‐synthesized carbon quantum dots (CQDs) were characterized using UV‐vis spectrophotometry, photoluminescence spectrophotometry, high‐resolution transmission electron microscopy, and Fourier transform infrared spectroscopy. The synthesized wheat‐CQDs (W‐CQDs) and oat‐CQDs (O‐CQDs) had monodispersed spherical shapes with average sizes of 3–8 and 5–10 nm, respectively, and exhibited strong fluorescence intensity and excitation‐dependent photoluminescence. The W‐CQDs and O‐CQDs were highly dispersed in aqueous solutions and exhibited bright green and blue fluorescence, respectively, under UV light (λex=380 and 370 nm). Both CQDs contained abundant functional groups, including amino, hydroxyl, and carboxyl groups, which may play a major role in biological applications. The W‐CQDs and O‐CQDs showed good free‐radical scavenging capacity in the 2,2‐diphenylpicrylhydrazyl (DPPH) and H2O2 assays. The anti‐inflammatory activities of W‐CQDs and O‐CQDs were more effective than that of the standard, with EC50 values of 1.8 and 1.3 mg/mL, respectively, in the protein denaturation assay. Additionally, the CQDs exhibited low cytotoxicity toward NIH3T3 fibroblast and human HeLa cervical cancer cells when treated with a 5‐mg/mL concentration. Therefore, green‐synthesized W‐CQDs and O‐CQDs are easily available, less cytotoxic, and applicable to therapeutic and cell nanocarrier purposes.

Decorating Pd-Au Nanodots Around Porous In2 O3 Nanocubes for Tolerant H2 Sensing Against Switching Response and H2 S Poisoning.

With the recently-booming hydrogen (H2 ) economy by green H2 as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H2 as a biomarker, H2 sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H2 sensinghas been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/In2 O3 NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/In2 O3 NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/In2 O3 NCBs show 300 ppb-low detection limit, 5 s-fast response to 500ppm H2 , 75%RH-high humidity tolerance, and 56 days-long stability at 280°C. Further, Pd-Au NDs/In2 O3 NCBs show excellent stability against switching sensing response, and are tolerant to H2 S poisoning even being exposed to 10ppm H2 S at 280°C. Such excellent H2 sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H2 and H2 S. Practically, Pd-Au NDs/In2 O3 NCBs are integrated into the H2 sensing device, which can reliably communicate with a smartphone.

Magnetic properties of nano(iron oxide)-decorated graphene oxide

Graphene oxide (GO) decorated with magnetic iron oxide nanoparticles is of great interest due to its potential applications in nanomedicine, electromagnetic insulation, and electro-catalysis. Herein, we studied the effect of the preparation conditions by hydrothermal synthesis on the phase composition of graphene oxide decorated with iron oxide nanoparticles. GO samples using two different amounts of a 2Fe3+/Fe2+ solution were prepared under a pH = 11, whereas hydrazine treatment was done to half the batch. Electron microscopy images show that Fe-oxide nanoparticles with an average size of 5–10 nm appeared decorating graphene platelets. Graphene oxide decorated rolls form in hydrazine-treated samples. Infrared spectra suggest a mixture of iron oxide phases with increased goethite upon hydrazine treatment. X-ray diffraction and X-ray Absorption Near Edge Structure spectroscopy (XANES) in the Fe K-edge determined the relative amount of the resulting iron oxide phases. Mixtures of magnetite, maghemite, hematite, and goethite were observed depending on the sample preparation conditions. The effect of phase composition on the magnetic properties was also studied. The saturation magnetization varied from 3.5 to ca. 50 Am2/kg at 300 K; it is proportional to the magnetite/maghemite content and reduces as the amount of goethite increases. The coercive field in the samples increases up to 1.6–2.4 mT at 300 K. The saturation magnetization has a slower decay with temperature when compared to a reference sample of magnetite nanoparticles, which suggests a magnetoelectric coupling due to the nanoparticle distribution onto the conductive graphene sheet.

Mo-doping and construction of the heterostructure between NiFe LDH and NiSx co-trigger the activity enhancement for overall water splitting

To reduce the preparation cost of high-purity hydrogen, it is necessary to search suitable non-precious metal catalysts with high activity and robust stability. Herein, two means (heteroatom-doping and the heterostructure construction) were adopted together to improve the dual-function activity of NiFe LDH which was widely used in water electrolysis. Mo doped NiFe LDH nanoflowers were firstly generated by hydrothermal reaction, and then NiSx was modified on the petals via electrodeposition. Finally, the obtained NF/Mo-NiFe LDH/NiSx with large electrochemical active area exhibits the expected electrochemical performance with the overpotential at 100 mA cm−2 of 169 and 249 mV for hydrogen evolution (HER) and oxygen evolution reaction (OER) respectively. Assembling NF/Mo-NiFe LDH/NiSx into a two-electrode device for the integral water electrolysis, it just requires a cell voltage of 1.69 V to drive a current density of 100 mA cm−2, and keeps stable after 50-hour continuous operation in 1.0 M KOH. Mo-doping not only regulates the electronic structure of the transition metals and reduces the energy barrier of HER intermediates, but also facilitates the generation of reactive sites for OER. Meanwhile, the construction of heterointerface ensures the synergism between NiSx and Mo-NiFe LDH and accelerates the electron transfer across interfaces, thus enhancing the bifunctional performance.

Synergistically accelerating capture and catalytic conversion of polysulfides by Co@NCNT-MoSe2 nanocomposite modified separator for advanced Lithium-Sulfur batteries

Lithium-sulfur (Li-S) battery with a high theoretical energy density (2600 Wh·kg−1) is considered as a promising energy storage system. However, the shuttle effect and the sluggish redox kinetics of lithium polysulfides (LiPSs) lead to low sulfur utilization. A multifunctional layer modified on separator, as a collaborator of capturer-catalyst-conductor, is be regarded as an effective strategy to solve these problems. Herein, the Co@NCNT-MoSe2 nanocomposite as a modified layer is synthesized with a mesoporous structure by the hydrothermal reaction, in which a large number of transparent MoSe2 nanosheets grow outside NCNT embedded with Co nanoparticles, forming a flower-like outer walls of tube. The modified layer displays the significant features of capturing and catalytic conversion toward LiPSs, attributing to strong adsorption abilities, abundant catalytic active sites, and efficient transferring pathway of electron/Li+. Benefitting from these alluring properties, the results demonstrate that the modified separator offers a high discharge capacity of 983.2 mAh·g−1 at 0.2C after 200 cycles. Even at 2C, after long-term 1000 cycles, it still shows a superb capacity of 725 mAh·g−1 accompanied by a low capacity fading of 0.042 % per cycle. More notably, at 0.2C, the modified separator can realize an ideal areal capacity of 5.24 mAh·cm−2 under high S load (5 mg·cm−2) and poor electrolyte (7.5 μL·mg−1). Therefore, this work will provide a new insight on the development of multifunctional separators to achieve a long-life battery with high sulfur utilization by restraining shuttle effect and accelerate redox kinetics of LiPSs.

One-step hydrothermal synthesis of sulfur quantum dots for detection of Hg2+ ions and latent fingerprints

High blue-emitting sulfur quantum dots (SQDs) with quantum yields of up to 58.7% were prepared using elemental sulfur using a facile ethylenediamine-assisted hydrothermal acceleration method at 60 °C for 7 h. In the presence of ethylenediamine, bulk sublimated sulfur powder can be broken down into fine particles of sulfur-nitrogen compounds and then oxidized to produce SQDs. HRTEM analysis of the morphology of SQDs showed that SQDs had a quasi-spherical shape with a size of 3.2 nm. In this process, under the influence of ethylenediamine, sublimated sulfur is rapidly converted from zero-valent sulfur to polysulfide with simple heating, greatly improving manufacturing efficiency. Synthesized fluorescent sulfur quantum dots (SQDs) were used in this study as fluorescent probes for quantitative detection of Hg2+. The SQD served as an effective Hg2+ detection probe with a detection limit of 2.7 μM through an efficient on-off switching mechanism in response to Hg2+. In addition, latent fingerprints were recognized using SQD powder, and fingerprints were detected on the surfaces of various media, such as paper, glass, and aluminum foil. The synthesized SQDs have a high potential for sensing applications of various luminescent materials.

A superhydrophobic zirconium‐based metal‐organic framework/cellulose fiber composite material

AbstractCleanup of oil spills has become one of the most challenging tasks in recent years, as marine oil spills have had a great negative impact on human health and the ecological environment. This also urgently requires the development of new materials and methods with superhydrophobic properties for oil–water separation. As new porous materials, metal–organic frameworks (MOFs) have attracted much attention due to their unique structures and fascinating properties. However, powdered MOF materials are difficult to recycle, and therefore, suitable substrates need to be selected to construct superhydrophobic composites. The surface hydroxyl groups of cellulose fibers offer great possibilities for their superhydrophobic preparation. In this paper, HDTMS‐UiO‐66@CFs composites with superhydrophobicity were strategically synthesized by in‐situ growth of Zr(IV)‐based MOFs linked to hexadecyltrimethoxysilane (HDTMS) on cellulosic fibers (cotton fabric) by using a hydrothermal synthesis method. The HDTMS‐UiO‐66@CFs composites have a water contact angle of 172° and the absorption capacity of light oil and heavy oil is more than 1100%, and the oil–water separation efficiency is as high as 96%. Due to the in‐situ growth of the HDTMS‐UiO‐66 material on cotton fibers, which makes the material more resistant and stable, the material can still maintain its superhydrophobic properties in various harsh environments and after repeated use. Therefore, the newly developed HDTMS‐UiO‐66@CFs composites have a high potential as novel adsorbent materials for cleaning up offshore oil spills and other applications.Highlights In‐situ growth of superhydrophobic metal‐organic frameworks (MOF) particles on cellulose fibers. The porous structure of hexadecyltrimethoxysilane (HDTMS)‐UiO66 plays a key role in hydrophobicity. HDTMS‐UiO66@CFs are chemically stable and have long‐term durability.

Optimization of hydrothermal synthesis conditions of Bidens pilosa-derived NiFe2O4@AC for dye adsorption using response surface methodology and Box-Behnken design.

The presence of stable and hazardous organic dyes in industrial effluents poses significant risks to both public health and the environment. Activated carbons and biochars are widely used adsorbents for removal of these pollutants, but they often have several disadvantages such as poor recoverability and inseparability from water in the post-adsorption process. Incorporating a magnetic component into activated carbons can address these drawbacks. This study aims to optimizing the production of NiFe2O4-loaded activated carbon (NiFe2O4@AC) derived from a Bidens pilosa biomass source through a hydrothermal method for the adsorption of Rhodamine B (RhB), methyl orange (MO), and methyl red (MR) dyes. Response surface methodology (RSM) and Box-Behnken design (BBD) were applied to analyze the key synthesis factors such as NiFe2O4 loading percentage (10-50%), hydrothermal temperature (120-180 °C), and reaction time (6-18 h). The optimized condition was found at a NiFe2O4 loading of 19.93%, a temperature of 135.55 °C, and a reaction time of 16.54 h. The optimum NiFe2O4@AC demonstrated excellent sorption efficiencies of higher than 92.98-97.10% against all three dyes. This adsorbent was characterized, exhibiting a well-developed porous structure with a high surface area of 973.5 m2 g-1. Kinetic and isotherm were studied with the best fit of pseudo-second-order, and Freundlich or Temkin. Qmax values were determined to be 204.07, 266.16, and 177.70 mg g-1 for RhB, MO, and MR, respectively. By selecting HCl as an elution, NiFe2O4@AC could be efficiently reused for at least 4 cycles. Thus, the Bidens pilosa-derived NiFe2O4@AC can be a promising material for effective and recyclable removal of dye pollutants from wastewater.

Sensing, detoxification and bactericidal applications of nitrogen-doped carbon dots

Here, a one-pot hydrothermal synthesis technique was used to create nitrogen-doped carbon dots (N-CDs). Their structural and optical properties were assessed using XPS, XRD, Raman, UV–Vis, and fluorescence spectrophotometer. The N-CDs demonstrated encouraging emission quenching towards p-NP (p-Nitrophenol) and developed a sensing approach between 0.25 and 125 μM concentrations, from which a linear equation with a 20 nM detection limit was generated. In comparison to river and circulating water samples, the practicality demonstrated positive recovery rates together with impressive accuracy and precision. Additionally, the multi-functionality of N-CDs was investigated further in the catalytic reduction of methyl orange (MO) dye. With a good regression coefficient(0.9904) (R2) and rate constant (Kcat) (0.0208 min−1), N-CDs were able to reduce the azo groups in 8 min completely. Additionally, the bactericidal efficiency of N-CDs against gram-positive (Staphylococcus aureus, Listeria monocytogenes) and gram-negative (Escherichia coli, Salmonella enterica) bacteria was encouraging. The well-diffusion method demonstrated a good zone of inhibition, and the microdilution method demonstrated a promising minimum bactericidal concentration (MBC) of 470–940 μg/mL and minimum inhibitory concentration (MIC) of 240–470 μg/mL. The suggested fluorescent material may prove useful in the future for creating a fluorescence sensor, catalysts to combat water pollution, and antibacterial sprays to combat dangerous microorganisms.

Engineering of Au nanoparticles over hollow MoS2/C nanoreactor for enhanced TEA sensing at low temperature

Surface modification with noble metal is an effective strategy to improve gas sensitive properties of semiconductive materials. Herein, hollow MoS2/C nanoreactors assembled with nanosheets were synthesized with the incorporation of water-oil two-phase microemulsion method and following heating treatment. Through adjusting the polarity of hydrothermal reaction solvent, Au nanoparticles (NPs) of different size were loaded on MoS2/C nanoreactors, whose average size could be efficiently tailored from 5.73 to 42.6 nm. The results of gas sensing measurement show that Au modification can remarkably increase triethylamine (TEA) sensing properties of MoS2/C–based sensor at lower temperature. Especially, for Au@MoS2/C-2 with Au NPs size of about 9.9 nm, the response value to 50 ppm TEA at 160 °C is high up to 240.5, which is 20 times higher than that of MoS2/C, and the response-recovery times are highly reduced from 80 s/500 s–13 s/198 s. Besides, Au@MoS2/C-2 sensitive element has excellent selectivity, humidity resistance, and long-term stability for TEA. This enhancement in TEA response is properly attributed to the modified interfacial interaction between Au NPs and MoS2/C, which leads to the formation of Schottky contact and boosts the charge transfer. So, hollow Au@MoS2/C nanoreactors will be a potential candidate for TEA detection.

One-Step Hydrothermal Synthesis of NVO Cathodes with Varied Lattice NH4 + Content: Effect on Structural Evolution and Electrochemical Performance.

Aqueous zinc ion batteries have been extensively researched due to their distinctive advantages such as low cost and high safety. Vanadium oxides are important cathode materials, however, poor cycle life caused by vanadium dissolution limits their application. Recent studies show that the lattice NH4 + in vanadium oxides can act as a pillar to enhance structural stability and play a crucial role in improving its cycling stability. Nevertheless, there is still a lack of research on the effect of the lattice NH4 + content on structural evolution and electrochemical performance. Herein, we synthesize vanadium oxides with different contents of lattice NH4 + by a one-step hydrothermal reaction. The vanadium oxides with lattice NH4 + exhibit high initial capacity, as well as good cycling stability and rate performance compared to bare vanadium oxide. Combined with electrochemical analyses, ex-situ structural characterizations, and in-situ X-ray diffraction tests, we reveal that the lattice NH4 + content plays a positive role in vanadium oxides' structural stability and cation diffusion kinetics. This work presents a direction for designing high-performance vanadium cathodes for aqueous zinc ion batteries.