Fluorine-doped carbon nitride (FC3N4) quantum dots were successfully synthesized on a large scale by a facile ethylene glycol-assisted ultrasonic method using bulk FC3N4 powder as the precursor and ethylene glycol as the solvent. Characterization results show that high-quality FC3N4 quantum dots with a uniform size of 1.5–2.0 nm were successfully prepared in ethylene glycol. Ethylene glycol is found to play an important role in the synthesis of quantum dots. Doping of fluorine in C3N4 could adjust the band gap structure of C3N4, resulting in altering the emission peak position and increasing the fluorescent intensity. The as-prepared FC3N4 quantum dots in ethylene glycol show much higher fluorescent intensity with the quantum yield of 39.03%. The prepared FC3N4 quantum dots were successfully applied as a fluorescent probe for bacterial imaging.

•LDHs modified filter paper for detection of heavy metal ions has been developed.•Fe(CN)64- or S2- were successfully intercalated into LDHs modified test strips.•The test strips can detect heavy mental ions by observing the color change.•The test strips were highly stable and reproducible.In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)64− or S2− anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10−6 mol L−1. Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields.

In this report, stable copper nanoparticles (Cu NPs) were prepared through a facile annealing process using humic acid as the reducing and stabilizing agents. The products were characterized by X-ray powder diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The prepared Cu NPs show remarkably intrinsic peroxidase-like activity, which can rapidly catalyze the oxidation of the peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H2O2 to produce a blue-color reaction. The detection limit of H2O2 by Cu NPs can be as low as 1.32 × 10−7 M. More importantly, the prepared Cu NPs show excellent stability, which can hardly be oxidized even after 6 months. Based on the aforementioned mechanism, a simple, rapid and selective colorimetric method for glucose detection was developed, and the detection limit of glucose was 6.86 × 10−7 M. This study provides a novel method for the preparation of stable Cu NPs, which may have widespread applications in the detection of glucose in the human body and pear juice.

In this study, copper nanoparticles modified graphitic carbon nitride nanosheets (Cu NPs/g-C3N4) as a novel peroxidase mimetic were successfully prepared by the calcination of dicyandiamide–Cu2+ complex with the assistance of humic acid. The morphology and structure of the product were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The prepared Cu NPs/g-C3N4 was found to have highly peroxidase-like activity, which can rapidly catalyze the oxidation of peroxidase substance 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue color in the presence of H2O2. Accordingly, a simple, selective and fast colorimetric method was developed for H2O2 and glucose detection. The prepared Cu NPs/g-C3N4 exhibited low detection limits of 3.2 × 10−8 M and 3.7 × 10−7 M for H2O2 and glucose, respectively, due to the excellent peroxidase-like activity of Cu NPs/g-C3N4 originating from the synergistic effect of Cu NPs and g-C3N4. In this work, we utilized the easily forming complex ability of dicyandiamide and Cu2+ ions to form a homogeneous precursor solution, and then obtained the CuNPs/g-C3N4 product; such a method may have wide applications in novel composite nanomaterial preparation. The product may have promising applications in medical diagnostics and biotechnology fields.

A nanomaterial of the chemical composition Cu2(OH)3Cl-CeO2 and with a large surface area is shown to be a viable peroxidase mimetic. It was synthesized by co-precipitation of an aqueous solution containing Ce(III) chloride, Cu(II) chloride and hexamethylenetetramine by adding an ionic liquid. The material was characterized by scanning electron microscopy and X-ray powder diffractometry. The composite possesses peroxidase-like activity and catalyzes the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine by H2O2 to produce a blue product. Based on this finding, a simple, rapid and selective colorimetric method was worked out for the determination of glucose and cholesterol by using the respective oxidases and by quantifying the H2O2 formed. Both glucose and cholesterol can be determined by this method at levels as low as 50 µM.

•Novel Ag/AgCl/Zn-Cr LDHs photocatalyst was prepared by an anion-exchange method.•Ag/AgCl particles were uniformly grown on the surface of Zn-Cr LDHs materials.•Ag/AgCl/Zn-Cr LDHs shows the best activity in the photodegradation of RhB.•Holes and O2− are the two main reactive species for RhB degradation.•The photocatalytic mechanism was proposed.A novel composite photocatalyst Ag/AgCl/Zn-Cr layered double hydroxides (LDHs) was prepared by a facile anion-exchange precipitation method. It was found that Ag/AgCl particles were uniformly grown on the surface of Zn-Cr LDHs materials on a large scale, and the composite shows well visible-light absorption ability. The photocatalytic degradation studies on Rhodamine B (RhB) indicate that Ag/AgCl/Zn-Cr LDHs composite shows enhanced visible-light photocatalytic abilities for degradation of organic pollutants than Ag/AgCl and Zn-Cr LDHs. The photocatalytic mechanism was analyzed by active species trapping experiments. It revealed that the h+ and O2− are the two main reactive species for RhB degradation by Ag/AgCl/Zn-Cr LDHs composite, and the proportion of h+ greatly increases compared to that of Ag/AgCl and Zn-Cr LDHs, indicating that an efficient charge separation is crucial for the enhancement of the photocatalytic activities. This work provides an approach to fabricate novel types of visible-light-induced composite photocatalysts for environment treatment.A novel composite photocatalyst Ag/AgCl/Zn-Cr LDHs was prepared by a facile anion-exchange precipitation method, which shows enhanced visible-light photocatalytic abilities for degradation of RhB.

Vancomycin (Van)- and terephthalate (TA)-comodified europium-doped layered double hydroxides (Van-TA-Eu-LDHs) nanoparticles were successfully prepared by a two-step method, in which, TA acted as a sensitizer to enhance the fluorescent property and Van was modified on the surface of LDH to act as an affinity reagent to bacteria. The obtained products were characterized by X-ray diffraction, transmission electron microscope and fluorescent spectroscopy. The results demonstrated that the prepared Van- and TA-comodified europium-doped layered double hydroxides (Van-TA-Eu-LDHs) nanoparticles with diameter of 50 nm in size showed highly efficient fluorescent property. Furthermore, due to the high affinity of Van to bacteria, the prepared Van-TA-Eu-LDHs nanoparticles showed efficient bacteria labelling by fluorescent property. The prepared nanoparticles may have wide applications in the biological fields, such as biomolecular labelling and cell imaging.

In this work, AgNPs and Van molecules were modified on the surface of LDH sheets via the reduction of Ag ions with glucose and the adsorption of Van. The products were characterized by high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and Fourier-transform (FT-IR) spectroscopy. The results demonstrated that a homogeneous distribution of AgNPs of 30 nm in size as well as Van molecules were attached onto the surface of the LDH sheets. Owing to their properties, they were demonstrated to be quite efficient for the simultaneous capture and disinfection of bacteria, and showed much higher bacteria disinfection properties to Escherichia coli (E. coli) and Staphyloccocus aureus (S. aureus) compared to Ag/LDH, Van/LDH and LDHs due to the combined effect of Ag and vancomycin. The prepared Van–Ag/LDHs effectively combined Van and AgNPs together using LDH sheets, overcoming the disadvantages of Van in that it only shows disinfection properties towards Gram-positive bacteria, and those of AgNPs in that they have low dispersity and stability, which may have wide applications in the field of sterilization.

In this paper, novel uniformly distributed silver sulfide/bismuth sulfide nanocomposites (Ag2S/Bi2S3 NCs) were prepared by using one-step method for the photocatalytic inactivation against Gram-negative bacteria Escherichia coli (E. coli) under solar light irradiation. The results showed that Ag2S/Bi2S3 NCs simultaneously had uniform platelets and coralloid particles with regular shape and perfect dispersion properties and could render the capability of absorbing a broad solar spectrum. The antibacterial tests demonstrated that higher bactericidal rate was obtained with 1.0 mg/mL of Ag2S/Bi2S3 NCs under solar light irradiation during 100 min at 37 °C. It was confirmed by using fluorescence method that hydroxyl radicals generated in the photocatalytic process were the major responsibility for the photoinactivation. This work provides a promising photocatalyst in the bactericidal fields.Highlights► Novel Ag2S/Bi2S3 nanocomposites were prepared by one-step method. ► Ag2S/Bi2S3 nanocomposites could be activated by absorbing a broad solar spectrum. ► Ag2S/Bi2S3 displayed excellent antibacterial activity against Escherichia coli. ► Hydroxyl radicals were confirmed to be the major responsibility for the photoinactivation.

In this study, a room temperature NH3 bubble templating technique is developed to prepare zinc hydroxystannate [ZnSn(OH)6] hollow core-shell microspheres. Then, via a hydrothermal recrystallizing process, ZnSn(OH)6 hollow core-shell microcrystals with polyhedral morphology can be successfully obtained. It was found that the concentration of NH4F plays a crucial role in the morphology of the product. The optimal condition for the formation of hollow core-shell ZnSn(OH)6 microcrystals is that the concentration of NH4F is at 0.25 mol L−1 while the concentration of NaOH is fixed at 0.25 mol L−1. Reaction time has also a great influence on the morphology of the product. With the reaction time prolonged, hollow core-shell ZnSn(OH)6 microspheres would gradually crystallize into hollow core-shell ZnSn(OH)6 polyhedral microcrystals. The samples have been characterized by means of X-ray power diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectra (XPS), selected area electron diffraction (SAED) and transmission electron microscopy (TEM). The formation mechanism of the ZnSn(OH)6 hollow core-shell microcrystals with polyhedral morphology has been discussed based on the experimental results.

NiSe2 tubular microcrystals assembled of nanoparticles have been prepared via a hydrothermal method in an ethanolamine and water mixed solution assisted by polyvinyl alcohol (PVA). The prepared tubular crystals with hexagonal structure are composed of nanoparticles with average diameter of 30 nm. It was found that the phase of the products could be adjusted by the molar ratio of the reactants (Ni/Se), and the morphology of the products could be greatly influenced by the quantity of surfactant PVA. Based on the experimental results, the possible formation mechanism of NiSe2 tubular microcrystals is also discussed.

In this work, AgNPs and Van molecules were modified on the surface of LDH sheets via the reduction of Ag ions with glucose and the adsorption of Van. The products were characterized by high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and Fourier-transform (FT-IR) spectroscopy. The results demonstrated that a homogeneous distribution of AgNPs of 30 nm in size as well as Van molecules were attached onto the surface of the LDH sheets. Owing to their properties, they were demonstrated to be quite efficient for the simultaneous capture and disinfection of bacteria, and showed much higher bacteria disinfection properties to Escherichia coli (E. coli) and Staphyloccocus aureus (S. aureus) compared to Ag/LDH, Van/LDH and LDHs due to the combined effect of Ag and vancomycin. The prepared Van–Ag/LDHs effectively combined Van and AgNPs together using LDH sheets, overcoming the disadvantages of Van in that it only shows disinfection properties towards Gram-positive bacteria, and those of AgNPs in that they have low dispersity and stability, which may have wide applications in the field of sterilization.

In this report, stable copper nanoparticles (Cu NPs) were prepared through a facile annealing process using humic acid as the reducing and stabilizing agents. The products were characterized by X-ray powder diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The prepared Cu NPs show remarkably intrinsic peroxidase-like activity, which can rapidly catalyze the oxidation of the peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H2O2 to produce a blue-color reaction. The detection limit of H2O2 by Cu NPs can be as low as 1.32 × 10−7 M. More importantly, the prepared Cu NPs show excellent stability, which can hardly be oxidized even after 6 months. Based on the aforementioned mechanism, a simple, rapid and selective colorimetric method for glucose detection was developed, and the detection limit of glucose was 6.86 × 10−7 M. This study provides a novel method for the preparation of stable Cu NPs, which may have widespread applications in the detection of glucose in the human body and pear juice.