Fabrication of sulphur-doped graphitic carbon nitride anchored Ag@AgCl electrocatalyst for the sensing of chloramphenicol

We have developed sulphur-doped graphitic carbon nitride (S-GCN) anchored Ag@AgCl electrocatalyst through a green technique for the first time for the electrochemical sensing of chloramphenicol. The Ag@AgCl nanoparticles were synthesized using Rhoeo discolor (Tradescantia spathacea) plant extract without the use of any external halide source. As per our knowledge, this is the first time Rhoeo discolor (Tradescantia spathacea) plant extract was used for the synthesis of Ag@AgCl nanoparticles without the use of any external halide source. Using sonochemical technique, the green synthesized nanoparticle was combined with S-GCN to form Ag@AgCl/S-GCN electrocatalyst. The synthesized materials were characterized by suitable techniques such as UV-visible spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and elemental analysis. The electrocatalytic reduction mechanism of chloramphenicol was studied with the help of electrochemical impedance spectroscopy, cyclic voltammetry, and linear sweep voltammetry. The Ag@AgCl/S-GCN modified electrode has shown a linear response in the range of 1 to 650 μM, with a LOD of 420  nM . Further, the practical application of the developed sensor was analyzed using real samples such as milk and honey and satisfactory recovery rates were observed.

Rapid and efficient colorimetric sensing of clindamycin and Fe3+ using controllable phyto-synthesized silver/silver chloride nanoparticles by Syzygium cumini fruit extract

Abstract

The first evidence of a green, single-step, and additive-free process for the fabrication of silver/silver chloride nanoparticles (Ag/AgCl NPs) by fruit extract of Syzygium cumini (S. cumini) without the usage of any stabilizer and halide source was provided. The formation of nanoparticles was optimized to control the shape, size, and stability via various pHs of the reaction mixture, the quantity of fruit extract, temperature, concentrations of silver ion, and reaction time. The optimal conditions were determined: pH = 7.0, the quantity of the leaf extract = 3.0 mL, silver ion concentration = 1.0 mM, temperature = 60 °C, and incubation time = 40 min. As an application in colorimetric sensing, the ability of the prepared Ag/AgCl NPs to sense clindamycin and Fe3+ ion in an aqueous medium was investigated. The SPR band and color of the solution of Ag/AgCl NPs undergo dramatic changes in exposure to clindamycin with new SPR peaks appearing at 500 nm, accompanied by a color change from yellow to pink due to the aggregation of NPs. Under the optimized pH of 3.0, this sensor was shown a linear dynamic range from 10.0 to 100.0 µM with a LOD of 1.2 µM and good linear relationships (R2 = 0.99) for clindamycin. On the other hand, the quenching of the SPR peak at 412 nm was used to monitor the Fe3+ ions with wide linear ranges of 10.0–350.0 µM under the optimized pH (pH = 9) with a LOD of 5.6 µM. In addition, the proposed sensor displayed applicability in the real sample containing clindamycin (in capsules and injection ampoules) and Fe3+ ions (in water samples) detection.

Graphical Abstract

Nanomaterial Synthesis in Ionic Liquids and Their Use on the Photocatalytic Degradation of Emerging Pollutants

The unique properties of ionic liquids make them suitable candidates to prepare nanoscale materials. A simple method that uses exclusively a corresponding bulk material and an ionic liquid—in this case, [P_6,6,6,14]Cl—was used to prepare AgCl nanoparticles and AgCl@Fe₃O₄ or TiO₂@Fe₃O₄ magnetic nanocomposites. The prepared nanomaterials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy. The photodegradation of atenolol as a model pharmaceutical pollutant in wastewater was investigated under ultraviolet–visible light irradiation using the different synthesized nanocatalysts. In the presence of 0.75 g·L⁻¹ AgCl nanoparticles, a practically complete degradation of 10 ppm of atenolol was obtained after 30 min, following pseudo-first-order reaction kinetics. The effect of different variables (concentrations, pH, oxidant agents, etc.) was analyzed. The recyclability of the nanocatalyst was tested and found to be successful. A degradation mechanism was also proposed. In order to improve the recovery stage of the nanocatalyst, the use of magnetic nanocomposites is proposed. Under the same experimental conditions, a slightly lower and slower degradation was achieved with an easier separation. The main conclusions of the paper are the suitability of the use of ionic liquids to prepare different nanocatalysts and the effectiveness of these at degrading an emerging pollutant in wastewater treatment.

Green synthesis of Ag@AgCl/Elaeagnus angustifolia seed nanocomposite using Elaeagnus angustifolia leaves: an amazing nanophotocatalyst with highly photocatalytic activity under sunlight irradiation

In this investigation, Ag@AgCl nanoparticles were synthesized by a green and inexpensive method using Elaeagnus angustifolia leaves, as a reducing and stabilizing agent without using any toxic solvent, external halide source, harsh chemicals, or capping agents. In this protocol, the nanophotocatalyst was synthesized via immobilization of Ag@AgCl NPs on the surface of biowaste Elaeagnus angustifolia seed (EAS) as a green support, which prevents the agglomeration Ag@AgCl NPs and improves the catalytic activity. The biosynthesized nanophotocatalyst were characterized by UV-Vis spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE SEM), energy dispersive X-ray spectroscopy (EDS), and transform electron microscopy (TEM) and inductively couple plasma mass spectrometry (ICP). In order to investigate the photocatalytic activity of the biosynthesized nanophotocatalyst, it was used in the degradation of methylene blue (MB) under sunlight. The results showed that nanophotocatalyst had an excellent photo activity without any agglomeration. In addition, the nanophotocatalyst can be easily be recycled and reused several times without losing its activity. Graphical abstract.

Green and simple synthesis route of Ag@AgCl nanomaterial using green marine crude extract and its application for sensitive and selective determination of mercury

Advanced exploitation in the green synthesis of nanomaterials has received considerable attention in the recent years. So that, an eco-friendly approach is proposed for the synthesis of silver‑silver chloride nanoparticles (Ag@AgCl-NPs) which does not require any external reducing & capping agents, organic solvent and external halide sources using an aqueous extract green marine alga (Chaetomorpha sp).In order to characterize the formation of Ag@AgCl-NPs, several instruments including UV-vis, FTIR, HR-TEM, EDS mapping, XRD, XPS, SAED and DLS were used. On the other hands, although numerous methods have been reported for the analysis of toxic Hg²⁺ in drinking water, development of simple, rapid, inexpensive, selective and sensitive sensors still remains a great challenge. Herein, the colorimetric sensor studies of this green synthesized Ag@AgCl-NPs showed an interesting feature for sensing of hazardous Hg²⁺ in water. The colorimetric assay is based on the concentration - dependent degradation of as-prepared Ag@AgCl-NPs in the presence of Hg²⁺. The detection limit of this affordable assay is 4.19 nM which is below the defined value by china agency and more importantly is below the defined by the U.S. Environmental Protection Agency for drinkable water.

Solid-state growth of Ag nanowires and analysis of the self-growing process on a bio-polymer chitosan film

The growth mechanism of silver nanowires (AgNWs) in solution has been thoroughly investigated and it has been demonstrated that factors like oxidative etching and inclusion of Cl- ions in the reaction system play critical roles in the formation of AgNWs. This research is the first to report the growth mechanism of AgNWs in the solid state on a chitosan polymer film with respect to factors such as oxidative etching, Cl- ions and time. The AgNW synthetic method is a green process that involves aqueous solvents for film preparation and ambient conditions for AgNW growth. It is demonstrated that the source of the silver precursor for this solid state AgNW growth is the cuboidal AgCl nanoparticles that form during the solution preparation. Furthermore, it is shown that the 〈111〉 crystal faces of these cuboidal AgCl nanoparticles are the nucleation sites of AgNW growth. Unlike solution-based AgNW synthetic processes, the AgNWs generated by the chitosan film-based method are irregular and present lateral as well as longitudinal growth, which suggests a slightly different mechanism from the solution-based AgNW growth.

Transformation of AgCl Particles under Conditions Typical of Natural Waters: Implications for Oxidant Generation

The engineered silver nanoparticles (AgNPs) used in consumer products are ultimately released to the environment either as Ag(0), silver sulfide (Ag₂S(s)), silver chloride (AgCl(s)), and/or dissolved Ag(I) complexes. Of these, AgCl(s) and Ag₂S(s) exhibit semiconducting properties and hence may have significant implications to oxidant generation and subsequent redox transformations in natural waters. In this work, we investigate the transformation and photoreactivity of AgCl(s) under simulated natural water conditions with the photoreactivity probed by measuring the oxidation of formate (HCOO^-), a simple compound with a well-defined oxidation pathway. Our results show that AgCl(s) undergoes rapid dissolution in the presence of chloride concentrations representative of seawater (ca. 0.5 M NaCl) forming dissolved Ag(I) complexes but is stable in fresh waters and slightly brackish waters (≤200 mM NaCl). We further show that under these lower salinity conditions in which AgCl(s) is stable, pH has a significant impact on the reactivity of semiconducting AgCl(s). The photoreactivity (measured as initial HCOO^- oxidation rate) of AgCl(s) is relatively constant at pH 4.0 for periods of 24 h or more; however, it decreases rapidly under alkaline conditions. The rapid transformation (or "aging") of AgCl(s) under alkaline conditions suggests that AgCl(s), potentially transported through wastewater effluent to fresh or brackish water environments, may not have a significant impact in such environments. In comparison, in situ formed AgCl(s), potentially formed as a result of the oxidation of high concentrations (≥60 μg Ag·L^-1) of Ag(0) and/or Ag₂S(s), may have significant implications to oxidant generation in natural waters. Our results further show that rapid cycling of Ag between the 0 and +I redox states in sunlit surface waters as a result of the presence of AgNP oxidants (such as H₂O₂ and organic radicals) will further enhance the rate and extent of oxidant generation by AgCl(s).

Photocatalytic degradation of methyl orange, methylene blue and rhodamine B with AgCl nanocatalyst synthesised from its bulk material in the ionic liquid [P6 6 6 14]Cl

The photocatalytic degradation of wastewater containing three industrial dyes belonging to different families, methyl orange (MO), methylene blue (MB) and Rhodamine B (RhB), was studied under UV-Vis irradiation using synthesised silver chloride nanoparticles. The nanocatalyst was prepared by a dissolution/reprecipitation method starting from the bulk powder and the ionic liquid trihexyl(tetradecyl)phosphonium chloride, [P_{6 6 6 14}]Cl, without addition of other solvents. The obtained catalyst was characterised by UV-Vis absorbance, X-ray powder diffraction, transmission electron microscopy and scanning electron microscopy. The decolourisation of the samples was studied by UV-Vis absorbance at the corresponding wavelength. Starting from 10 ppm dye solutions and 1 g L^-1 of the synthesised AgCl nanoparticles, degradation efficiencies of 98.4% for MO, 98.6% for MB and 99.9% for RhB, were achieved in 1 h. The degradation mechanisms for the different dyes were studied. Comparison with other frequently used nanocatalysts, namely P-25 Degussa, TiO₂ anatase, Ag and ZnO, highlights the strong catalytic activity of AgCl nanoparticles. Under the same experimental conditions, these nanoparticles led to higher (more than 10%) and faster degradations.

Green synthesis of multi-metallic nanocubes

A facile synthetic route and growth mechanism of heterobimetallic cubical nanoparticles Au@AgCl and Ag@AgCl@Au have been developed using Muntingia calabura flower extract.

Cube-like Ag/AgCl fabricated via a photoirradiation method and its substantially boosted plasmonic photocatalytic reactivity by an oxidation–chloridization treatment

Cube-like Ag/AgCl species are produced by a photoirradiation method, where substantially boosted plasmonic photocatalytic reactivity has been realized via an oxidation–chloridization treatment.

A rapid, facile and green synthesis of Ag@AgCl nanoparticles for the effective reduction of 2,4-dinitrophenyl hydrazine

In this study, we have developed a green and single-step process for the fabrication of Ag@AgCl nanoparticles (NPs) using the leaf extract ofMomordica charantia.

Controlling the morphology and composition of Ag/AgBr hybrid nanostructures and enhancing their visible light induced photocatalytic properties

Ag/AgBr hybrid nanostructures were prepared by reducing AgBr nanoparticles synthesized by reaction of Ag⁺ with Br⁻. The Ag/AgBr hybrid nanostructures exhibited enhanced photocatalytic activity and recyclability for decomposing methylene blue (MB).

A facile synthesis of Ag/AgCl hybrid nanostructures with tunable morphologies and compositions as advanced visible light plasmonic photocatalysts

Ag/AgCl plasmonic photocatalysts are synthesized by a simple and rapid method in an aqueous-phase. The Ag/AgCl hybrid nanostructures exhibited enhanced photocatalytic activity and stability toward the degradation of methyl orange under visible light irradiation because of their strong surface plasmon resonance (SPR) effect.

A special Ag/AgCl network-nanostructure for selective catalytic degradation of refractory chlorophenol contaminants

Ag/AgCl network-structures exhibit high photocatalytic performance for the selective degradation of 4-CP under UV-light, suggesting potential application for organic pollutant elimination.

Sustainable synthesis of highly efficient sunlight-driven Ag embedded AgCl photocatalysts

Microbe-free broth synthesis was performed under solar light to give Ag nanoparticle embedded AgCl in 5 minutes with superior performance than P25 for organic pollutant degradation.

Advanced nanoarchitectures of silver/silver compound composites for photochemical reactions

Silver/silver compound (SSC) composites have received much attention as a type of potential materials in photochemical reactions due to their high efficiency, facile syntheses and availability of raw materials. This article reviews the state-of-the-art progress on the advanced nanoarchitectures of SSC composites. We begin with a survey on the general synthetic strategies for SSC composites, and then step into relatively detailed methods for size and morphology tunable two-component and more delicate multi-component SSC nanostructures. In addition, the electronic structure-related mechanisms of such materials and the recent studies on their stability are summarized. This review also highlights some perspectives on challenges related to the SSC composites and the possible research in the future.

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity

In this study, a 'green chemistry' approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO- and NH2 + groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.