[en] Removal of organic contaminants from aqueous environment by photo-degradation is a highly attractive and energy effective technology. Herein, we have fabricated ternary nanocomposites of Ag₃PO₄ by integrating into conducting GO matrix along with magnetic Fe₃O₄ nanoparticles and demonstrated highly efficient photocatalytic activity and easy separation. Fe₃O₄-GO hybrid materials fabrication methods strongly influenced on the photocatalytic activity of Ag₃PO₄. Integrating Ag₃PO₄ nanoparticles into Fe₃O₄-GO (Ag₃O₄-Fe₃O₄-GO-C) by co-precipitation approach exhibited stronger photocatalytic activity against Rhodamine B compared to hydrothermally prepared Fe₃O₄-GO (Ag₃O₄-Fe₃O₄-GO-H). Rhodamine B was degraded completely (100 %) in 15 min using Ag₃O₄-Fe₃O₄-GO-C whereas more than 45 min was required for Ag₃O₄-Fe₃O₄-GO-H. PXRD studies confirmed the formation of crystalline Fe₃O₄ and Ag₃PO₄ in both the samples. HR-TEM analysis confirmed the integration of Fe₃O₄ and Ag₃PO₄ in the GO sheets. XPS studies indicated the presence of all elements in Ag₃O₄-Fe₃O₄-GO-H and Ag₃O₄-Fe₃O₄-GO-C. Integration of magnetic Fe₃O₄ allowed easy separation and reusing of catalysts.

[en] We report nonlinear optical (NLO) investigations of few pyrazines with terminal donor groups and the influence of graphene oxide (GO) on their nonlinear absorption (NLA) under the nanosecond (ns) pulse excitation. We have used Z-scan and Degenerate Four-Wave Mixing (DFWM) techniques for the NLO investigations and a Q switched Nd:YAG laser (532 nm, 7 ns, 10 Hz) was used as the source of excitation. Modified Hummers method was used for synthesizing GO. A significant quenching in the fluorescence intensity of the pyrazine derivatives was observed when incorporating GO and it suggests the interaction between GO and pyrazine moieties through electron/energy transfer. The pyrazines/GO composites showed strong NLA and it is better than that of the parent compounds. The mechanism behind the NLA is found to be two-photon absorption (TPA) along with excited-state absorption (ESA) and the significant enhancement in the NLA activity of composites can be attributed to the photo induced electron and/or energy transfer between the GO and pyrazine moieties. (author)

[en] We developed a green, inexpensive and simple method for the synthesis of silver nanoparticles from the Opuntia Ficus (OF) Indica fruit juice. The synthesized AgNPs were used as sensor for the detection of toxic metal $({\text{Hg}}^{2+})$ using colorimetric technique as well as to investigate the antimicrobial activities against number of clinical isolates of human microbes. The synthesized AgNPs nanoparticles were characterized using UV–Vis spectroscopy, FTIR spectroscopy, scanning electron microscopy and EDX methods. The green synthesized AgNPs showed surface plasmon resonance absorption band at 441 nm, which confirm the formation of AgNPs that were also established by FTIR and EDX analyses. The colour of AgNPs changes from blood red to white in the presence of ${\text{Hg}}^{2+}$ only, which can be differentiated and detected by the naked eye within few seconds without the prerequisite of surface amendment from other metals (Co, Ni, Fe, Mn, Pb, Zn, Cr). A good linear response ($R^2=0.97$) was obtained towards ${\text{Hg}}^{2+}$ ions in the concentration range of ${10}^{-<!--\; ???\; -->3}$ to ${10}^{-<!--\; ???\; -->8}\text{ M}$. In addition, all growth of the tested microbial stains ceased in varied range. OFAg-2 had the highest inhibition effect followed by OFAg-1, while OF did not show any antimicrobial activities. Candida albican and Klebsiella pneumonia are the most susceptible microbes by OFAg-2 and OFAg-1 respectfully. Klebsiella oxytocam, Proteus mirabilis and Klebsiella oxytoca had the moderate susceptibility from OFAg-2 and OF, while Staphylococcus aureus was found to be the lowest susceptible microbes. Therefore, OFAg-2 and OFAg-1 probably could be promising pharmaceutical agents against many microbial strains.

[en] Waste water remediation is the ongoing hot research topic that can reduce the water scarcity all over the world. By reducing the pollutants in the waste water drawn from industries and other sources will be more useful for domestic purposes. To reduce the rate of pollutants in water may also help in improving the aquatic environment and decreases other side effects. Efficient and cost effective catalysts were in search for both dye degradation and water remediation treatment applications. NiMoO₄ nanorods were prepared by employing co-precipitation method with different stirrer time (2 h, 4 h and 6 h). The formation of NiMoO₄ was substantiated employing X-ray diffractometer analysis (XRD). Vibrational and rotational property of the samples was analyzed by FT-IR spectra and Raman spectra. The optical property was further confirmed by UV–vis spectral studies. Morphological analysis studies revealed growth of nanorods with 6 h stirrer time. The photocatalytic behavior of the obtained product was carried out under both UV light (364 nm) and visible light irradiation. The samples subjected to visible light environment showed better efficiency on degrading the methylene blue (MB) dye. The efficiency obtained under UV irradiation were 20%, 31%, 33%, 41% and efficiency obtained in visible light irradiation were 27%, 42%, 46%, 55% with respect to bare methylene blue (MB), MB with NiMoO₄ (2 h), MB with NiMoO₄ (4 h), MB with NiMoO₄ (6 h) catalyst added. NiMoO₄ sample with 6 h stirrer time and fine nanorods growth will be the good candidate for future use.

[en] Herein we reported the effect of doping and addition of surfactant on SnO₂ nanostructures for enhanced photocatalytic activity. Pristine SnO₂, Zn–SnO₂ and SDS-(Zn–SnO₂) was prepared via simple co-precipitation method and the product was annealed at 600 °C to obtain a clear phase. The structural, optical, vibrational, morphological characteristics of the synthesized SnO₂, Zn–SnO₂ and SDS-(Zn–SnO₂) product were investigated. SnO₂, Zn–SnO₂ and SDS-(Zn–SnO₂) possess crystallite size of 20 nm, 19 nm and 18 nm correspondingly with tetragonal structure and high purity. The metal oxygen vibrations were present in FT-IR spectra. The obtained bandgap energies of SnO₂, Zn–SnO₂ and SDS-(Zn–SnO₂) were 3.58 eV, 3.51 eV and 2.81 eV due to the effect of dopant and surfactant. This narrowing of bandgap helped in the photocatalytic activity. The morphology of the pristine sample showed poor growth of nanostructures with high level of agglomeration which was effectively reduced for other two samples. Product photocatalytic action was tested beneath visible light of 300 W. SDS-(Zn–SnO₂) nanostructure efficiency showed 90% degradation of RhB dye which is 2.5 times higher than pristine sample. Narrow bandgap, crystallite size, better growth of nanostructures paved the way for SDS-(Zn–SnO₂) to degrade the toxic pollutant. The superior performance and individuality of SDS-(Zn–SnO₂) will makes it a potential competitor on reducing toxic pollutants from wastewater in future research.

[en] Three-dimensional (3D) cobalt molybdate (CoMoO₄) hierarchical nanoflake arrays on pencil graphite electrode (PGE) (CoMoO₄/PGE) are actualized via one-pot hydrothermal technique. The morphological features comprehend that the CoMoO₄ nanoflake arrays expose the 3D, open, porous, and interconnected network architectures on PGE. The formation and growth mechanisms of CoMoO₄ nanostructures on PGE are supported with different structural and morphological characterizations. The constructed CoMoO₄/PGE is operated as an electrocatalytic probe in enzyme-less electrochemical glucose sensor (ELEGS), confronting the impairments of cost- and time-obsessed conventional electrode polishing and catalyst amendment progressions and obliged the employment of a non-conducting binder. The wide-opened interior and exterior architectures of CoMoO₄ nanoflake arrays escalate the glucose utilization efficacy, whilst the intertwined nanoflakes and graphitic carbon layers, respectively, of CoMoO₄ and PGE articulate the continual electron mobility and catalytically active channels of CoMoO₄/PGE. It jointly escalates the ELEGS concerts of CoMoO₄/PGE including high sensitivity (1613 μA mM⁻¹ cm⁻²), wide linear glucose range (0.0003–10 mM), and low detection limit (0.12 µM) at a working potential of 0.65 V (vs. Ag/AgCl) together with the good recovery in human serum. Thus, the fabricated CoMoO₄/PGE extends exclusive virtues of modest electrode production, virtuous affinity, swift response, and excellent sensitivity and selectivity, exposing innovative prospects to reconnoitring the economically viable ELEGSs with binder-free, affordable cost, and expansible 3D electrocatalytic probes. Graphical abstract:

[en] A new fluorophore, (2Z)-3-[4-(dimethylamino) phenyl]-2-(4-fluorophenyl) prop-2-ene-nitrile (DPF), was synthesized by knoevenagel condensation of 4-(dimethylamino) benzaldehyde and 4-fluorobenzyl cyanide in ethanol using NaOH as base. The electronic absorption and emission characteristic of DPF were studied in different solvents. The X-ray crystallographic structure of DPF was also investigated. DPF exhibits a red-shift in its emission spectrum as solvent polarity increases, indicating a large change in the dipole moment of dye molecule upon excitation due to intramolecular charge transfer in excited DPF^⁎. The fluorescence quantum yield depends strongly on the properties of the solvents, which was attributed to positive and negative solvatokinetic effects. A crystalline solid of DPF gives a strong yellow emission at about 532 nm; these phenomena are important for the application of DPF dye in organic photoemitting diode. The photochemical quantum yield of cis–trans isomerization of DPF was also determined in different solvents. The DPF dye displays solubilization in both cationic (CTAB) and anionic (SDS) micelle and may be used as a probe to determine the critical micelle concentration (CMC) of SDS and CTAB. - Highlights: • Organic pi conjugated molecule with a donor acceptor group was studied. • Crystalline solid of the molecule shows strong and intense yellow emission. • The dye displays solubilization in cationic micelle with abrupt change in emission intensity at CMC. • This work gives an insight into the application of organic luminescent material in various fields

[en] The rational design and development of surfactant- and binder-free catalytic nanostructures on cost-efficient electrode could establish influential pathways in generating the effectual enzyme-free electrochemical sensing platforms. Accordingly, the cost-efficient flame synthesis strategy is realized for synthesizing nitrogen-doped carbon nanoparticles (NCNPs) on Indium tin oxide (ITO) via the burning of pyrrole under air atmosphere and the growth process is lasted for 3 min. Envisioned with the significant objectives of rapid electron transfer from the core to shell, prevention of the agglomeration of nanoshell architectures, and influential contact of analyte with the core, the development of CuO nanorods on NCNPs in the form of core–shell architecture is accomplished via the hydrothermal technique. The synergistic properties of core and shell architectures and uniform dispersion of electrochemically active and stable sites of NCNPs@CuO catalytically favor the glucose oxidation. Being a glucose sensor, NCNPs@CuO/ITO demonstrates the considerable electro-oxidation performances along with the other constructive features including high selectivity, reproducibility, reusability, and durability, which favor the realization of the practical applicability of fabricated sensor in human serum samples. Thus, the established research effort not only demonstrates a scalable methodology for the synthesis of core–shell architectures but also advances the scopes of cost-efficient glucose detection.

[en] Highlights: • MnS@MoS₂ architectures are prepared by using a simple hydrothermal technique∙MnS@MoS₂ modified TBFP is used as an electrochemical probe for H₂O₂ sensing∙Growth and formation mechanisms of MnS@MoS₂ architectures are illustrated∙Mn(IV)/Mo(IV) centres engaged H₂O₂ electroreduction mechanism is schematized∙MnS@MoS₂/TBFP establishes effectual non-enzymatic H₂O₂ sensing performances∙MnS@MoS₂/TBFP’s real sample H₂O₂ sensing relevancy is actualized in human urine -- Abstract: We report here the rational development of MnO₂ nanorods coated tea bag filter paper (TBFP) as a self-standing, bendable, and disposable electrochemical probe for the sensitive and selective H₂O₂ detection and addresses their challenges in H₂O₂ sensing via the replacement of ‘O’ with ‘S’ in the form of MnS microcubes and its core@shell architecture with MoS₂. The as-configured MnS@MoS₂/TBFP overwhelms the constrains of conventional electrochemical probes including time and cost consumed electrode surface renewability and catalyst loading progression, and the practice of an insulating binder. The hierarchical open porous architectures of MoS₂-shell favour the diffusion of H₂O₂ into the core-MnS microcubes, facilitating an analyte utilization efficacy at both the core and shell architectures. The impacts of core@shell morphological features, replacement of ‘O’ with ‘S’, surface defects, and lattice distribution of MnS@MoS₂ toward non-enzymatic H₂O₂ sensing performances are elucidated using variant electrochemical techniques. With the synergism of uniformly implanted and exposed metallic active sites, efficient electron transfer rate, and high analyte utilization efficiency, MnS@MoS₂/TBFP exposes the low detection limit (120 nM), excellent sensitivity (650 μA mM⁻¹ cm⁻²), and wide linear range (500 nM-5 mM) on H₂O₂ detection. Furthermore, the scrutinized non-enzymatic H₂O₂ detection concerts of MnS/MoS₂/TBFP are selective, decisive, repeatable, and stable, constructing the excellent recovery rates in human urine sample analyses. Thus, the collective benefits of free-standing, flexible, binder-less, re-functional, and cost-efficient MnS@MoS₂/TBFP probe actualize the evolution of affordable and high performance H₂O₂ sensors.