Chemical Reduction Method Research Articles

Nanosized amorphous nickel-boron alloy electrocatalysts for hydrogen evolution reaction under alkaline conditions

Hydrogen production from electrolyzed water driven by sustainable energy is an effective way to achieve the hydrogen economy with zero carbon emission. Alkaline electrocatalytic hydrogen evolution reaction (HER) is one of the main energy transforming processes in the field of electrolytic water technology. The development of active and cost-effective nonprecious catalytic electrodes is of great importance to alkaline hydrogen evolution reaction. Amorphous nanosized nickel-boron alloy particles (NiB-COS) have been obtained by using chitosan oligosaccharides (COS) as a stabilizer via chemical reduction method. The as-prepared electrocatalysts have been used for the hydrogen evolution reaction (HER). The electrocatalysts have been characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma analysis (ICP) and X-ray photoelectron spectroscopy (XPS). NiB-COS displays a significant increase in hydrogen evolution reaction properties in alkaline media, affording low overpotentials of 49.4 mV at 10 mA/cm2 and 15.1 mV onset overpotential for the hydrogen evolution reaction. Tafel slope of NiB-COS is 86.1 mV/dec. Remarkably, the formation of a nickel-boron alloyed phase and the decrease of particle size are helpful to improve HER activity of NiB-COS. The experimental data indicated that the NiB-COS showed excellent long-term stability as a very active electrocatalyst.

Palladium nanoparticles combined with reduced graphene oxide and multiwall carbon nanotubes for alkaline ascorbic acid oxidation

Ascorbic acid (vitamin C) is recognized as a viable alternative fuel for alkaline direct liquid fuel cells. After the potential anode catalyst was prepared by incorporating palladium nanoparticles (Pd NPs) into reduced graphene oxide (rGO) and multiwall carbon nanotube (MWCNT) hybrid nanocomposite (Pd/rGO/MWCNT) through a chemical reduction method, it was applied for electrooxidation of ascorbic acid (AA) in the alkaline condition. For AA electrooxidation, the Pd/rGO/MWCNT modified glassy carbon electrode (Pd/rGO/MWCNT/GCE) exhibited the highest current density of 5.18 mA cm−2: much higher than a bare glassy carbon electrode (0.6 mA cm−2). The Pd/rGO/MWCNT/GCE also demonstrated excellent stability for AA oxidation in the alkaline condition.

Room-Temperature Synthesis of Thioether-Stabilized Ruthenium Nanocubes and Their Optical Properties.

Controlling the nucleation and growth processes for nanoparticle synthesis allows the development of well-defined structures that offer unique chemical and physical properties. Here, we report a wet chemical reduction method for synthesizing ruthenium nanocubes (Ru NCs) that display plasmonic properties at room temperature (RT). The growth of the particles to form nanostructured cubes was established by varying the carbon chain length of the thioether stabilizing ligands and the reaction time to produce stable and controlled growth. In this study, we found that the longer the thioether chain length, the less isotropic the shape of the particles. Short chain lengths of thioethers (ethyl sulfide and butyl sulfide) produced spherical nanoparticles, whereas longer chain lengths (hexyl sulfide and octyl sulfide) produced cubic nanoparticles. In addition, parameters such as the ligand to precursor ratio also played an important role in the homogeneity of the nanocubes. The Ru NCs were characterized by UV-visible absorbance spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which supported a face-centered cubic (fcc) structure. Moreover, to demonstrate catalytic efficiency, we studied their ability to reduce benzaldehyde to benzyl alcohol, and the Ru NCs demonstrated an overall 78% efficiency at room temperature.

Synthesis of Iron Nanoparticles Capped by Citric Acid or Citrates and its Characterizations

We report the synthesis of iron nanoparticles (FeNP) using the chemical reduction method with citric acid and trisodium citrate as reduction agents and capping material. The FeNP was obtained in a homogenous yellow transparent solution. The result obtained from using the reduction agent of citric acid and trisodium citrate yield an average spherical size of 100.7 nm and 97.4 nm, respectively. We observed a broad peak in UV-vis spectra of FeNP in the range of 273 nm to 279 nm. This peak is associated with a fluorescence excitation of iron nanoparticles as well as their aggregates.

Copper nitride/silver nanostructures synthesized via wet chemical reduction method for the oxygen reduction reaction

This work presents attempts to synthesize silver-doped copper nitride nanostructures using chemical solution methods. Copper(II) nitrate and silver(I) nitrate were used as precursors and the oleylamine as a reducing and capping agent. Homogeneous Cu3N/Ag nanostructures with a diameter of ~ 20 nm were obtained in a one-pot synthesis by the addition of the copper(II) salt precursor to the already-synthesized silver nanoparticles (Ag NPs). Synthesis in a two-pot procedure performed by adding Ag NPs to the reaction medium of the Cu3N synthesis resulted in the formation of a Cu3N@Ag nanocomposite, in which Ag NPs are uniformly distributed in the Cu3N matrix. The morphology, structure, and chemical composition of the obtained specimens were studied by TEM, XRD, XPS, and FT-IR methods, while optical properties using UV–Vis spectroscopy and spectrofluorimetry. The band gap energy decreased for Cu3N/Ag (Eg = 2.1 eV), in relation to pure Cu3N (Eg = 2.4. eV), suggesting the insertion of Ag atoms into the Cu3N crystal lattice. Additionally, Cu3N and Cu3N/Ag nanostructures were loaded on graphene (GNP) and tested as a catalyst in the oxygen reduction reaction (ORR) by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The Cu3N/Ag-modified GNP hybrid material revealed catalytic activity superior to that of Cu3N-based GNP hybrid material and pure GNP, comparable to that of a commercial Pt/C electrode.Graphical

Platinum-Tellurium Alloy Metallene Toward Formic Acid Oxidation Reaction

Open AccessRenewablesRESEARCH ARTICLES14 Jan 2023Platinum-tellurium alloy metallene towards formic acid oxidation reaction Ya-Nan Li, Qing-Ling Hong, Bo-Qiang Miao, Tian-Jiao Wang, Yu Ding and Yu Chen Ya-Nan Li Google Scholar More articles by this author , Qing-Ling Hong Google Scholar More articles by this author , Bo-Qiang Miao Google Scholar More articles by this author , Tian-Jiao Wang Google Scholar More articles by this author , Yu Ding Google Scholar More articles by this author and Yu Chen Google Scholar More articles by this author https://doi.org/10.31635/renewables.022.202200005 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Engineering the composition and/or morphology is highly effective strategy for enhancing the electrocatalytic performance of noble metal nanocrystals. Recently, metallenes with specific chemical and physical properties have attracted increasing attention in electrocatalysis field. In this work, two-dimensional ultrathin platinum-tellurium alloy metallene (PtTe A-ML) is synthesized by using a conventional liquid-phase chemical reduction method. The high atom utilization as well as alloy effect endow PtTe A-ML with preeminent electrocatalytic activity for the formic acid oxidation reaction (FAOR). Specifically, the direct oxidation pathway of FAOR can be completely achieved at PtTe A-ML, which suppresses the production of toxic carbon monoxide (CO) intermediates and improves the reaction kinetics of FAOR. Accordingly, the FAOR activity of PtTe A-ML in acidic media is 43 and 5.6 times higher than that of commercial Pt and Pd nanocrystals, respectively. Meanwhile, PtTe A-ML exhibits also excellent electrocatalytic activity for CO oxidation reaction because of the introduction of oxygenophilic Te atoms and electron transfer between Pt and Te, which elevates the durability of PtTe A-ML for FAOR. The study provides a simple synthesis strategy of PtTe A-ML and shows PtTe A-ML has a promising practical prospect in direct formic acid fuel cells. Download figure Download PowerPoint Next article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2023 Chinese Chemical Society Downloaded 4 times PDF downloadLoading ...

Thiol‐Functionalized Palladium Nanoparticles Networks: Synthesis, Characterization, and Room Temperature (Toxic) Vapor Detection

AbstractThe preparation of three different functionalized palladium nanoparticles (PdNPs) systems for room temperature BTX (benzene, toluene, p‐xylene) sensing detection and their morphostructural characterization is described. PdNPs are prepared through a two‐phase water/toluene wet chemical reduction method in the presence of bifunctional organic thiols as stabilizing agents suitable for the formation of covalently linked PdNPs networks: p‐terphenyl‐4,4″‐dithiol (PdNPs‐TR), biphenyl‐4,4′‐dithiol (PdNPs‐BP), or with 9,9‐didodecyl‐2,7‐bis(acetylthio)fluorene (PdNPs‐FL). Comparing the hydrodynamic diameter values, TR and BP ligands help to obtain networks consisting of spherical NPs of about 2 nm, in which each bifunctional ligand act as a bridge between PdNPs. In contrast, PdNPs‐FL show a population centered at <2RH> = 45 ± 5 nm. To perform preliminary gas sensing measurements, PdNPs networks are cast deposited on interdigitated electrodes to study their resistive response toward volatile organic compounds (VOCs) such as benzene (0–5%), toluene (0–1.7%), and p‐xylene (0–0.4%) (BTX) and common interfering gases (H2S, NH3, SO2, and relative humidity, RH). PdNPs‐FL show enhanced response to BTX with an appreciable response also toward H2S and RH. PdNPs‐TR exhibit a better ability to discriminate benzene gas with a negligible response after H2S exposure. Moreover, all the PdNPs systems show little to no response to NH3 and SO2 gases, offering an interesting perspective in practical sensing applications.

Pd-Ni-B/C Nanocatalysts for Electrochemical Oxidation of Ethanol in Alkaline Media

This paper describes the synthesis of Pd<sub>0.70</sub>-Ni<sub>x</sub>-B<sub>y</sub> nanoparticles (x:y = 0.30:0, 0:0.30, 0.25:0.05, 0.20:0.10, 0.15:0.15, and 0.10:0.20) supported on carbon Vulcan XC-72 R by the chemical reduction method using ethylene glycol as a reducing agent for the study of the electrochemical oxidation of ethanol in alkaline media. Neither surfactants nor templates were used during the syntheses. The catalysts were physically characterized by transmission electron microscopy that showed the formation of nanoparticles with diameters of approximately 3 nm. Analyses of X-ray dispersive energy spectroscopy coupled with scanning electron microscopy identified the presence of the synthesized metals in concentrations close to the nominal ones. The electrochemical study was performed by CO-stripping, cyclic voltammetry, chronoamperometry, and steady-state polarization curves. The catalytic efficiency was also evaluated against the oxidation of CO, which is the principal intermediate adsorbed on the surface of catalysts during ethanol oxidation. The Pd<sub>0.70</sub>Ni<sub>0.15</sub>B<sub>0.15</sub>/C catalyst showed the lowest oxidation onset potentials for both CO (0.37 V) and ethanol oxidation (0.51 V) compared with the Pd/C catalyst (0.63 V and 0.64 V). Chronoamperometric tests also revealed that the Pd<sub>0.70</sub>Ni<sub>0.15</sub>B<sub>0.15</sub>/C catalyst displayed current densities four times higher than those of the Pd/C catalyst, probably because of the electronic and geometric effect that favors the removal of intermediate species from the catalyst surface. The synthesized ternary catalysts were more efficient toward the electrochemical oxidation of ethanol in alkaline media than Pd<sub>0.7</sub>Ni<sub>0.3</sub>/C and Pd/C catalysts. Thus, the synergistic effect of boron on the structure of binary nanoparticle catalysts supported on carbon for use in direct alcohol fuel cells was demonstrated for the first time.

Preparation and characterization of nano-solder paste with high nanoparticle loading and their thermal and printing properties

A lead-free nano-solder paste has been successfully prepared by dispersing tin-silver (Sn–Ag) nanoparticles within a flux using planetary mixing, with nanoparticle loading up to 50 wt%. An aqueous chemical reduction method was used to synthesize the Sn–Ag alloy nanoparticles. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to image the morphology of the nanoparticles and the size was estimated to be an average of 19.6 ± 3.6 nm. Composition of the Sn–Ag nanoparticles was measured using energy dispersive x-ray spectroscopy (EDS) and their crystal structures were analyzed via x-ray diffraction (XRD). Differential scanning calorimetry (DSC) measurements of the Sn–Ag nanoparticles, containing approximately 4 wt% Ag, showed an onset of melting at 219.8 °C and an endothermic peak at 222.5 °C. These measured values for the nanoparticles are slightly lower as compared to the corresponding bulk material. The synthesized Sn–Ag nanoparticles were dispersed within a flux using planetary mixing, forming a uniform nanosolder paste, and as high as 50 wt% nanoparticle loading was achieved. Multiple heating cycles of the Sn–Ag nanosolder paste via DSC showed 1.6 °C increase in the onset of melting between the first and fourth cycles. Thermogravimetric analysis (TGA) of the 50 wt% nanosolder paste showed a 76% retention of initial weight up to 250 °C and 56% up to 500 °C, indicating residual material remaining on solder materials after heating. The nanosolder paste was screen-printed and reflowed on Cu substrates in an inert environment. The cross-section of the interface was observed via FE-SEM for intermetallic compound (IMC) formation between the reflowed nanosolder paste and substrate, confirming that a metallurgical bonding has been achieved. Both Cu3Sn and Cu6Sn5 were observed in the interfacial layer.

Microwave-assisted method synthesis of Ag/CNQDs/g-C3N4 with excellent photocatalytic activity for the degradation of norfloxacin

In this paper, through microwave-assisted process combined with a chemical reduction method, the novel ternary photocatalysts Ag/CNQDs/g-C3N4 composites were prepared successfully for the norfloxacin removal. The Ag/CNQDs/g-C3N4 composites possessed the suitable specific surface area, better crystal structure and excellent stability. Furthermore, forming an internal electric field, the isotype heterojunction structure between CNQDs and g-C3N4 could promote effective carrier separation. Unexpectedly, the Ag/CNQDs/g-C3N4 with the synergistic effect of the up-conversion fluorescent properties of CNQDs and the surface plasmon resonance (SPR) effect of Ag NPs, showed the excellent photocatalytic property. As a result, the optimized Ag/CNQDs/g-C3N4 composites exhibit excellent photocatalytic degradation of norfloxacin under visible light irradiation. The norfloxacin removal rate was reached almost 100% within 120 min, and the quasi-first-order kinetic constant (k) value was 0.04233 min−1, which was more than 4 times higher than that of g-C3N4. Moreover, the·O2- and h+ were the dominant active species involved in the photo-degradation of norfloxacin. In the mineralization process, the toxicity of norfloxacin degradation intermediates gradually reduced. This work not only provides new insights for the design of g-C3N4-based composites for photocatalysis applications, but also affords an effective strategy in the environmental remediation field.

Simultaneous fluorescence sensing of vitamin B2 and sulfur ions based on fluorescent copper nanoparticles

In this study, the F-CuNPs were synthesized by a modified liquid-phase chemical reduction method. Throughout the preparation process, anhydrous copper sulfate was used as the copper source, and ascorbic acid in the NaOH solution served as the reducing and protective agent. Förster resonance energy transfer (FRET) may exist between F-CuNPs and vitamin B2 due to the large spectral overlap between the fluorescence emission spectra of F-CuNPs and the UV–vis absorption spectra of vitamin B2. Therefore, the detection of vitamin B2 was designed based on a FRET system between F-CuNPs and vitamin B2. With S2− into the F-CuNPs&VB2 system, the fluorescence intensity of vitamin B2 was quenched, while the fluorescence intensity of F-CuNPs was almost unchanged. There may be a specific reaction between S2− and vitamin B2. Therefore, the research system can be further used to detect S2− based on ratiometric fluorescent probe. The research findings show that the linear range of vitamin B2 was 0.51 nM–34.64 nM with a detection limit of 0.25 nM (S/N = 3), the linear range of S2− was 0.64 μM–60.00 μM with a detection limit of 0.32 μM (S/N = 3). Furthermore, the simultaneous fluorescent sensing system has high sensitivity and selectivity. Therefore, this system was designed and successfully used to detect the content of vitamin B2 and S2− in actual samples to find a new effective method to detect analytes.

Facile Synthesis and Fabrication of NIPAM-Based Cryogels for Environmental Remediation.

Herein, polymeric cryogels containing poly(N-isopropylacrylamide) were synthesized by cryo-polymerization at subzero temperature. The synthesized cryogels were loaded with silver and palladium nanoparticles by the chemical reduction method at room temperature using the reducing agent NaBH4. Moreover, for comparison with cryogels, pure poly(N-isopropylacrylamide) hydrogel and its silver hybrid were also prepared by the conventional method at room temperature. The chemical structure and functional group analysis of the pure cryogels was confirmed by Fourier transform infrared spectroscopy. The synthesis of hybrid cryogels was confirmed by the X-ray diffraction technique and energy dispersive X-ray. The pore size and surface morphology of the pure cryogels, their respective hybrid cryogels and of conventional hydrogels were studied by using the scanning electron microscopy technique. The hybrid cryogels were successfully used as a catalyst for the degradation of methyl orange dye. The degradation performance of the hybrid cryogels was much better than its counterpart hybrid hydrogel for methyl orange dye. The effect of temperature and amount of catalyst on catalytic performance was studied by UV-visible spectroscopy. The reduction follows pseudo-first-order reaction kinetics. In addition, the antibacterial activities of these cryogels were evaluated against Gram-positive bacteria (Staphylococcus aureus, ATCC: 2593) and Gram-negative bacteria (Escherichia coli, ATCC: 25922). Both hybrid cryogels have shown much better antibacterial activity for these two strains of bacteria compared to pure cryogels. The results indicate that these cryogels are potential candidates for water purification systems as well as biomedical applications.

Exploring the Magnetic and Electrocatalytic Properties of Amorphous MnB Nanoflakes

Two-dimensional (2D) metal borides are a class of ceramic materials with diverse structural and topological properties. These diverse material properties of metal borides are what forms the basis of their interdisciplinarity and their applicability in various research fields. In this study, we highlight which fundamental and practical parameters need to be taken into consideration when designing nanomaterials for specific applications. A simple one-pot chemical reduction method was applied for the synthesis of manganese mono-boride nanoflakes at room temperature. How the specific surface area and boron-content of the as-synthesized manganese mono-boride nanoflakes influence their magnetic and electrocatalytic properties is reported. The sample with the highest specific surface area and boron content demonstrated the best magnetic and electrocatalytic properties in the HER. Whereas the sample with the lowest specific surface area and boron content exhibited the best electric conductivity and electrocatalytic properties in the OER.

Ir-IrO2 with heterogeneous interfaces and oxygen vacancies-rich surfaces for highly efficient oxygen evolution reaction

The development of efficient and stable catalysts for oxygen evolution reaction (OER) has recently attracted much attention, and the major challenge of current research is to offer fast kinetics and enhance the durability in a harsh oxidising environment. Herein, an effective strategy is developed to construct a unique heterogeneous interface between Ir nanoclusters and IrO2 via a facile and scalable chemical reduction method, followed by the thermal treatment under Ar atmosphere. Both the transmission electron microscope and X-ray photoelectron spectroscopy results revealed that the as-prepared Ir-IrO2 has been engineered with heterogeneous interfaces and oxygen vacancies-rich surfaces. Benefited from newly-formed active surfaces and the oxygen vacancies-rich surfaces, the Ir-IrO2 catalyst exhibits increased catalytic active sites and enhanced catalytic activity towards the OER compared with the pure IrO2 and commercial IrO2. The over-potential of the Ir-IrO2 is ca. 329 mV at 10 mA cm−2, and the mass activity is ca. 1851 A gIrO2−1 at 1.60 V (vs. RHE), about 2.4 times that of the commercial IrO2 (ca. 779 A gIrO2−1). In addition, both the improved catalytic performance and durability for the OER is further confirmed in PEM water electrolysis cell.

Comportamiento antibacteriano y análisis de resistencia bacteriana de P. aeruginosa al contacto con nanopartículas de cobre

The present study describes the antibacterial behavior and the bacterial resistance analysis of extremophile Pseudomonas aeruginosa in contact with copper nanoparticles (CuNPs). For this purpose, green synthesis of CuNPs was performed by combined ultrasound-assisted and chemical reduction methods, obtaining semispherical CuNPs ranging from ca. 4-9 nm. Antibacterial activity (AA) of biosynthesized CuNPs demonstrates an antibacterial inhibition of 85 % (LD85) at 400 μg/mL and a minimum bactericidal concentration (MBC) of 800 μg/mL after 3 h of contact. Bacterial adaptation in contact with CuNPs was observed through the consecutive exposition of microorganisms, presenting a significant increase of LD85 values from 400 μg/mL to 6400 μg/mL after 11 expositions. This behavior demonstrates the bacterial growth adaptation with high-dose of CuNPs. The bacterial resistance mechanism was determined through the overproduction of pyocyanin, associated with oxidative stress events, the genomic polymorphism of resistant bacteria obtained by PCR-RAPDs, and the morphological interaction between P. aeruginosa and CuNPs evidenced by transmission electron microscopy (TEM) micrographs. Our results suggest that under controlled CuNPs exposition, extremophile P. aeruginosa can generate bacterial resistance mechanisms, an important issue for the effective design of antimicrobial nanomaterials.

Polypyrrole-Coated Low-Crystallinity Iron Oxide Grown on Carbon Cloth Enabling Enhanced Electrochemical Supercapacitor Performance

It is highly attractive to design pseudocapacitive metal oxides as anodes for supercapacitors (SCs). However, as they have poor conductivity and lack active sites, they generally exhibit an unsatisfied capacitance under high current density. Herein, polypyrrole-coated low-crystallinity Fe2O3 supported on carbon cloth (D-Fe2O3@PPy/CC) was prepared by chemical reduction and electrodeposition methods. The low-crystallinity Fe2O3 nanorod achieved using a NaBH4 treatment offered more active sites and enhanced the Faradaic reaction in surface or near-surface regions. The construction of a PPy layer gave more charge storage at the Fe2O3/PPy interface, favoring the limitation of the volume effect derived from Na+ transfer in the bulk phase. Consequently, D-Fe2O3@PPy/CC displayed enhanced capacitance and stability. In 1 M Na2SO4, it showed a specific capacitance of 615 mF cm-2 (640 F g-1) at 1 mA cm-2 and still retained 79.3% of its initial capacitance at 10 mA cm-2 after 5000 cycles. The design of low-crystallinity metal oxides and polymer nanocomposites is expected to be widely applicable for the development of state-of-the-art electrodes, thus opening new avenues for energy storage.

Silver nanoparticle based efficient colorimetric assay for carbaryl – An insecticide

Metal nanoparticles capped with polymers have been employed for multiple analytical and biomedical applications. In this study, highly stable polypropylene glycol (PPG) capped silver nanoparticles (PPG-AgNPs) were synthesized by chemical reduction method. The characterization of PPG-AgNPs was performed by zeta sizer, UV–visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy energy dispersive X-ray (FESEM-EDX), and atomic force microscopy (AFM). Moreover, PPG-AgNPs were employed as a chemosensor for an insecticide of the carbamate family, Carbaryl. PPG-AgNPs based colorimetric assay render a quantitative, rapid, selective, and efficient detection of carbaryl in an analytical range of 0.05–100 µM in the presence of several other pesticides/insecticides, salts, and drugs. The limit of detection and quantification of the proposed assay for carbaryl were as low as 0.005 µM and 0.016 µM, respectively. The major strength of the proposed PPG-AgNPs based assay is its efficiency for on-spot detection of carbaryl in ecological, biological, and food samples away from a sophisticated laboratory setup. While the quantitative performance of the proposed sensor for carbaryl is comparable with UPLC and UV–Vis spectroscopy in standard conditions, the performance of the PPG-AgNPs based CAR sensor stands out for environmental, biological, and food samples.

Chitosan Salts as Stabilizing Agents for the Synthesis of Silver Nanoparticles (AgNPs)

AbstractIn this work, silver nanoparticles (AgNPs) were obtained by a chemical reduction method using different chitosan salts as stabilizing agents, able to protect and prevent against the aggregation of the nanoparticles. Various chitosan salts with different organic acids, which included: acetic, succinic, formic, propionic, malic, glycolic and lactic acid were used to form the chitosan salts. The use of these organic acids represents a viable, sustainable, environmentally friendly and economical way to synthesized AgNPs. The AgNPs‐chitosan salts samples were analyzed by UV‐VIS, ATR‐FTIR spectroscopy, DLS, and TEM. Most of the organic acids led to nanoparticles with small dimensions (30–52 nm) and positive zeta‐potential. However, those AgNPs‐chitosan that were stabilized by the salts of α‐hydroxyacids and diacids, like glycolate and succinate, led to larger particles. The stability study under different storage conditions and time showed that the silver nanoparticles are more stable when storage at cold temperatures.

Facile fabrication of an Au/Cu bimetallic nanocluster-based fluorescent composite film for sensitive and selective detection of Cr(VI).

To overcome the disadvantage of simple bimetallic nanocluster solutions being difficult to store and utilize, we prepared and obtained a novel gold and copper bimetallic nanocluster-doped chitosan fluorescent composite film. In this study, gold and copper bimetallic nanoclusters emitting strong red fluorescence were first synthesized by a chemical reduction method. Subsequently, a novel gold and copper bimetallic nanocluster-doped chitosan fluorescent composite film was successfully prepared by a solution casting method. After 60 minutes of UV light irradiation or 30 days at room temperature, the relative fluorescence intensity values of the composite film decreased by 0.9% and 1.2%, respectively. This indicates that its optical properties are stable and that it can be stored for a long time. The composite film has strong and bright red fluorescence and can be used as a fluorescent probe to achieve real-time detection of Cr(VI). It also has a low detection limit for Cr(VI) (0.26 ppb), so it can be applied to the detection of Cr(VI) in actual water samples and get satisfactory detection results. Due to its portability, high selectivity, and high sensitivity, it can also be extended to chemical and food detection.

Surface modification of polypropylene nonwoven with chitosan, TiO2, and Ag nanoparticles for the removal of acid dye from water.

In this study, polypropylene nonwoven was coated with chitosan after being activated by oxygen/argon low-pressure plasma. The chitosan-treated sample (PP-Ch) was coated with TiO2 nanoparticles by a pad-dry method. Silver nanoparticles were in situ synthesized on the chitosan-TiO2-coated sample by a chemical reduction method. The morphology of each of the samples mentioned above was evaluated by FESEM. The efficiency of each sample in the removal of C.I. Acid Brown 248 from aqueous media was evaluated. The PP-Ch sample removed 90% of the dye at pH=3. Coating the PP-Ch sample with TiO2 and silver nanoparticles improved the dye removal efficiency under UV irradiation.