Search

A dinuclear dysprosium(iii) complex [Dy2(NO3)3(L)3]·nCH3OH (n = 1.20; HL = (2-[(2-hydroxy-propylimino)methyl]phenol)) (1) was isolated when dysprosium nitrate reacted with a solution of salicylaldehyde and 1-amino-2-propanol in a basic medium under in-situ reaction conditions.

The triangulo-{Er3} complex [Er3Cl(o-van)3(OH)2(H2O)5]Cl3·nH2O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method.

Catalytic activities of graphitic carbon nitride (g-C3N4) are restricted thanks to inadequate visible light absorption and high rate electron–hole recombination. In this work, we synthesized porous g-C3N4 using polycondensation process. Structural and physico-chemical characteristics of the prepared g-C3N4 materials were studied via XRD, DRS, PL, FTIR, Raman spectroscopy, SEM, BET and CHN elemental analyzer. The prepared samples exhibited surprising catalytic activity for the photo-oxidation of rhodamine-B (RhB) in visible light irradiation. From the fabricated g-C3N4 materials, the g-C3N4-550 showed photodegradation efficiency of 100% towards the RhB pollutant in water within 30 min. No appreciable decrease of the photocatalytic efficiency of g-C3N4 was observed up to five consecutive cycles, confirming the synthesized g-C3N4 was highly stable. Thus, this work gave a simple process for large scale production of highly visible light responsive and stable g-C3N4 materials used for environmental remediation.

Magnetically separable all-solid-state Z-scheme g-C3N4/graphene/NiFe2O4 (CGN) nanocomposites have been synthesized using one pot hydrothermal method. The as-prepared pristine and nanocomposite samples were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), UV–VIS diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface analysis, and Vibrational sample magnetometer (VSM) characterization techniques. The result reveals that the weight percent of NiFe2O4 have considerable effect on the optical property and photocatalytic activity of the nanocomposites. The CGN-25% nanocomposite shows the best photocatalytic activity and its activity is about 15, 7 and 6 folds higher than those of NiFe2O4, g-C3N4, and CN-25% respectively on the degradation of methyl orange (MO). This enhancement could be attributed to the synergistic effect between g-C3N4, graphene and NiFe2O4, which could accelerate photogenerated electron-hole separation and prolong the life of the photo-induced carriers to enhance their activity. The CGN-25% was recycled using magnet without significant loss and shows almost the same photocatalytic performance for six runs. Moreover, a possible photocatalytic mechanism was proposed. This could provide new insights to develop highly efficient and stable g-C3N4 and graphene based magnetic photocatalysts.

Poly[3-(2′,5′-dioctyloxyphenyl)thiophene] (PDOOPT), poly[3-(2′,5′-diheptyloxyphenyl)thiophene] (PDHOPT) and poly[3-(2′,5′-dibutyloxyphenyl)-thiophene] (PDBOPT) have been prepared electrochemically from their monomers within nanocrystalline titanium dioxide (nc-TiO2) porous surface deposited on indium doped tin oxide coated glass (ITO-glass) for solar cell application. The redox properties of the polymers were characterized using cyclic voltammetry. The energy levels of the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) have been estimated from their cyclic voltammograms and UV–vis absorption spectra. The poly[3-(2′,5′-dialkoxyphenyl)thiophenes] studied sensitize nc-TiO2 in liquid-state photoelectrochemical cells. Devices that consist of PDBOPT/nc-TiO2 photoactive electrode showed improved performance over those that consist of PDHOPT/nc-TiO2 and PDOOPT/nc-TiO2. PDBOPT/nc-TiO2 based devices produced an open-circuit voltage of 0.56 V, a short-circuit current of 45 μA/cm2, and a fill factor of 0.52 when illuminated with white light intensity of 80 mW/cm2.

A comparative study was done between liquid-state photoelectrochemical cells (PECs) consisting of photoactive electrodes of poly(3-hexylthiophene), P3HT, and a composite film of nanocrystalline titanium dioxide (nc-TiO 2 ) and P3HT. The nc-TiO 2 /P3HT based device shows better performance with an open-circuit voltage of 0.51 V, a short-circuit current of 0.31 mA/cm 2 , and a fill factor of 0.51 when illuminated with white light intensity of 100 mW/cm 2 . The IPCE% obtained at 550 nm for P3HT based device was 0.18% while for that of the nc-TiO 2 /P3HT based device was 4%. In P3HT based devices, P3HT showed its p-type behavior while in nc-TiO 2 /P3HT based devices, P3HT acted as a sensitizer to nanocrystalline TiO 2 .

Poly[3-(2\',5\'-diheptyloxyphenyl)thiophene], PDHOPT, has been prepared electrochemically from its monomer for solar cell application. PDHOPT exhibits a band gap of 2.1 eV. The redox properties of PDHOPT were characterized using cyclic voltammetry. The estimated energy levels of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are -5.3 eV and -3.2 eV, respectively. PDHOPT sensitizes nanocrystalline titanium dioxide (nc-TiO 2 ) in liquid-state photoelectrochemical cells. Devices where the photoactive electrode consists of nc-TiO 2 /PDHOPT composite film show improved performance over those that consist of only PDHOPT. Devices made of TiO 2 /PDHOPT composite film produced an open-circuit voltage of 0.52 V, a short-circuit current of 29 μA/cm 2 , and a fill factor of 0.54 when illuminated with white light intensity of 80 mW/cm 2 . KEY WORDS : Liquid-state photoelectrochemical cell, Nanocrystalline titanium dioxide, PDHOPT, I 3 - /I - redox couple Bull. Chem. Soc. Ethiop. 2007 , 21(3), 405-417.

Photoelectrochemical cells (PECs) have been fabricated using the emeraldine base form of polyaniline (EB) as a photoactive material and Eu2+/Eu3+ redox couple in methanol as an electrolyte. A PEC with a structure: Glass/ITO/EB/electrolyte/Pt produces an open-circuit voltage (V OC) of -0.132 V and a short-circuit current (I SC) of 0.64 µA cm-2 under 50 mW cm-2 white light illumination from Xe lamp. In an effort to increase the photoresponse, a PEC with a structure: Glass/ITO/EB:Nc-TiO2/Electrolyte/Pt has been devised in which a composite film of EB and nanocrystalline TiO2 (Nc-TiO2) is used as a photoactive material. The cell shows a V OC of -0.205 V and an I SC of 105 µA cm-2 when illuminated under the same conditions. Células fotoeletroquímicas (PECs) têm sido fabricadas usando a forma base esmeraldina de polianilina (EB) como um material fotoativo e o par redox Eu2+/Eu3+ em metanol como eletrólito. Uma célula fotoeletroquímica com a estrutura: Vidro/ITO/ EB:Nc-TiO2/Eletrólito/Pt produz uma voltagem de circuito-aberto (V OC) de -0,132 V e uma corrente de curto-circuito (I SC) de 0,64 µA cm-2 sob 50 mW cm-2 de iluminação com luz branca de lâmpada de Xe. Num esforço para aumentar a foto-resposta, uma PEC com estrutura: Vidro/ITO/ EB:Nc-TiO2/Eletrólito/Pt foi construída, na qual um filme composto de EB e TiO2 (Nc-TiO2) nanocristalino é usado como material fotoativo. A célula mostra uma V OC de -0,205 V e uma I SC de 105 µA cm-2 quando iluminada sobre as mesmas condições.