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Graphene quantum dots (GQDs) are a new class of materials that have replaced the conventional bimetallic dots with their unique properties. In the present study GQDs, N doped GQDs (N-GQDs) and S doped GQDs (S-GQDs) are synthesized by in-situ one step method of pyrolysis of citric acid (bottom up technique). The fabrication of florescent GQDs and doped GQDs with heteroatom N and S are evidently supported with transmission electron microscopy (TEM) and FT-IR. The mechanism of the photoluminescence in these quantum dots is investigated thorough the photoluminescence spectroscopy (PL) which was further reinforced by the electrochemical impedance spectroscopy (EIS) and with cyclic voltammetry. N-GQDs shows blue colored emission while S-GQDs shows relatively longer wavelength yellow green colored emission. Emission from the defective surface sites of the doped GQDs was confirmed from the proposed mechanism of PL of these dots. [ABSTRACT FROM AUTHOR]

The double composite layer composed of europium and terbium doped zinc oxide (Eu3+,Tb3+@ZnO) as downconversion material (DC) and neodymium and ytterbium-doped zinc oxide (Nd3+,Yb3+@ZnO) as upconversion materials (UC) was prepared and used as photoanodes to achieve the higher photovoltaic efficiency of dye sensitized solar cell(DSSCs). The double composite layer FTO/Eu3 + ,Tb3+@ZnO/TiO2/ Nd3+,Yb3+@ZnO have two disparate units; one provide downconversion luminescence by Ultraviolet excitation assigned to 7F0-5L6 of Eu3+, 7D4-7F5, of Tb3+, 5D4-7F4 of Tb3+, 7F0-5D1 of Eu3+ and other gives upconversion luminescence (λex = 980 nm) attributed to 4F7/2-4I15/2, 2H11/2-4I15/2,4S3/2-4I15/2,4F9/2-4I15/2. The photoelectric efficiency of double composite layer device E (FTO/Eu3+,Tb3+@ZnO/TiO2/Nd3+,Yb3+@ZnO) attains 2.68%, notably higher than device with undoped zinc oxide (ZnO). Higher efficiency in device E was due to enhancement of the light harvesting achieved by down converters and upconverters by converting Ultraviolet (UV) and near infrared (NIR) radiations to visible emission respectively. Furthermore, Eu3+,Tb3+@ZnO acts as confinement layer which suppresses the dark current and also inhibits the charge recombination. [ABSTRACT FROM AUTHOR]

Five luminescent Eu(III)-4-fluoro-N-salicylideneaniline (Fsa) complexes with different N,N′- donor heterocyclic ligands (L) were synthesized (where L = 2,2′-bipyridine (bipy), 4,4′-dimethoxy-2,2′-bipyridine (dmbp), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neo) and 2,2′-biquinoline (biq)) and characterized by structural, thermal and spectroscopic analyses. The photophysical studies of the complexes viz. UV-Vis absorption spectra, emission spectra, lifetime decay curve, radiative, non-radiative transition rates and quantum yields were investigated. The photophysical properties indicated that fluorine substituted salicylideneaniline acts as a better sensitizer for Eu3+ ion after involvement of ancillary ligands which leads to efficient energy transfer resulted in bright red emission due to 5D0 → 7F2 transition. The highest overall quantum yield (32.78%) and sensitization efficiency (75.30%) of [Eu(Fsa)3neo] showed that it is a potential candidate in optical field.Sensitization of europium(III)-Schiff base complexes by antenna effect [ABSTRACT FROM AUTHOR]

Potato peel (POPL), an agricultural waste material, obtained from food industry has been used as filler in the powdered form in linear low-density polyethylene (LLDPE) matrix up to 40% (w/w) to prepare biocomposites. The effect of addition of functional polyolefin compatibilizers—maleic anhydride-grafted polypropylene (MA-g-PP) and maleic anhydride-grafted polyethylene (MA-g-LLDPE), up to 5% (w/w) in POPL/LLDPE biocomposites were also studied. Scanning electron microscope was used for morphological characterization and X-ray diffraction for crystallization studies. Tensile strength of LLDPE biocomposites with MA-g-LLDPE compatibilizer reduced only in the range of 12.0-13.4 MPa compared to 14.6 MPa in neat LLDPE, however, reduced up to 40% in LLDPE biocomposites with 40% POPL content. Remarkable improvement in tensile modulus from 75.7 to maximum 703 MPa was achieved among the biocomposites. Mechanical properties of LLDPE biocomposites with 10% (w/w) POPL filler were comparable to neat LLDPE. Addition of maleic anhydride-grafted polyolefins has enhanced flexural strength and flexural modulus of biocomposites with compatibilizers’ up to 128 and 188%, respectively, compared to neat LLDPE. Low values of water absorption were observed for the biocomposites. The study showed that potato peel powder as inexpensive and potentially sustainable filler in the preparation of LLDPE biocomposites which could be biodegradable and environmentally friendly. [ABSTRACT FROM AUTHOR]

In this communication, bare indium tin oxide (ITO) electrode has been proposed for electrochemical detection of toxic metal ions. Simultaneous detection of Pb2+, Cu2+ and Hg2+ was achieved using cyclic voltammetry. Further, the bare ITO was also subjected to differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) for sensing of Cu2+. The analytical parameters of the developed sensor established, that the simultaneous limit of detection (LOD) for Cu2+ was 0.15 ppm which is under the recommended values by World Health Organization and the United States Environment Protection Agency. DPV and EIS also resulted in a comparable LOD for Cu2+ using bare ITO electrode suggesting it to be a better alternative than modified electrodes. [ABSTRACT FROM AUTHOR]

Conducting ternary photocatalyst, PEDOT@ZnO@GQDs with porous structure was synthesized using chemical oxidative polymerization. The fabricated photocatalyst was characterized by means of various spectroscopic techniques namely UV-Visible, FT-IR, XRD and the surface morphology was explored by SEM and TEM. Electro-catalytic activity of the photocatalyst has been studied by cyclic voltammetry. The kinetics of the photocatalytic degradation of the cationic dyes namely MB and R6G were studied in presence of PEDOT@ZnO@GQDs irradiated with UV light and solar light. The photocatalyst showed efficient photodegradation capacity due to the synergized effect of all three components namely PEDOT, ZnO and GQDs. The photocatalyst degraded the dyes in presence of solar light more efficiently. Photodegradation of the dyes follow first order kinetics, the kinetic parameters viz. rate constant and half life time period of the degradation of the dyes was evaluated through the plotted linear curves of concentration versus time. [ABSTRACT FROM AUTHOR]

Polypyrrole nanofibers/ meso-tetra(4-sulfonatophenyl)porphyrin/graphene quantum dots nanohybrid (PTG) was synthesized by a facile chemical oxidative reaction using persulfate salt of cetyltrimethylammonium cation ((CTA)SO) as the oxidative template. The facile formation and interactions among different constituents were established by FT-IR, UV-Vis, XRD and XPS studies. Morphological analysis was carried out by SEM and HRTEM showing polypyrrole nanofibers (PNF) to be formed with diameters in the range of 29-57 nm and HRTEM micrographs depicted the intercalation of meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) and graphene quantum dots (GQDs) with PNF. The electrical conductivity of PNF and PTG was evaluated using four-probe conductivity measurement. Electrochemical activity of PNF and PTG deposited on indium tin oxide (ITO) electrode was demonstrated using cyclic voltammetry with Fe(CN) as the redox species. PTG electrode displayed an enhanced voltammetric response vis-à-vis PNF due to the synergistic effect of PNF, TSPP and GQDs resulting in an increased electroactive area beneficial for a sensing probe. Further, the PTG electrode was checked for its capability to simultaneously detect Cd and Pb in aqueous solution by differential pulse voltammetry (DPV). [ABSTRACT FROM AUTHOR]