فهرست مطالب

Chemistry of Solid Materials
Volume:1 Issue: 2, Spring 2013

  • تاریخ انتشار: 1395/03/24
  • تعداد عناوین: 6
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  • Jahanbakh Raoof, Seyed Reza Hosseini, Reza Ojani Pages 1-13
    In this work, spherical Pt nanometer-scale particles supported on the poly (m-toluidine)/Triton X-100 film modified carbon nanotube paste electrode (Pt/PMT (TX-100)/MCNTPE) was used as a potent catalyst for electrooxidation of formaldehyde (HCHO) in both 0.5 M H2SO4 and 0.1 M NaOH solutions. The obtained results showed that utilization of TX-100 as an additive during the electropolymerization process enhances the electrocatalytic activity of the modified electrode towards HCHO oxidation. The onset potential of HCHO oxidation was shifted in 0.1M NaOH to less positive values than that of the acid solution which is due to the solution pH. Then, the influences of some parameters such as potential sweep rates, switching potential, and HCHO concentration on its oxidation have been investigated to provide the first insight into the electrooxidation behavior of HCHO in the alkaline medium. Also, stability of the modified electrode was examined by potential cycling in both acidic and alkaline solutions and the obtained results showed that in 0.1 M NaOH solution, a sufficient improvement was noted. The present study shows a promising choice of the Pt/PMT (TX-100)/MCNTPE as composite catalyst for HCHO oxidation at a reasonable low overpotentials.
    Keywords: Electrocatalytic oxidation, Triton X, 100, Pt nanoparticles, Carbon nanotube, Formaldehyde
  • Seyed Javad Mousavi* Pages 15-24
    We have investigated the electronic structure and thermodynamic properties of supercell of the -Al2O3 by first-principles calculation in framework of density functional theory (DFT) and full potential linearized augmented plane wave (FP-LAPW) with generalized gradient approximation (GGA) and by quasi-harmonic Debye model. Our calculated value for direct band gap of α-Al2O3 is 7.2 eV which is very close to its experimental measurement. Through the quasi-harmonic Debye model, in which the phononic effects are considered, we have obtained successfully the thermodynamic parameters including the relative volume and heat capacity over a pressure range 0-70 Gpa and a wide temperature range of 0-2000 K.
    Keywords: Band structure, Electric, thermodynamics properties, Density functional theory
  • Alireza Khorshidi, Sirous Heidari Pages 25-32
    Incorporation of [Fe(bipy)Cl4][bipy.H] (1) (where bipy is 2,2′-bipyridine) in the molecular sieves of the type LTA, NaY and mesoporous Al-MCM-41 by using a “ship in a bottle synthesis” approach was investigated. [Fe(bipy)Cl4][bipy.H] was successfullyincorporated in the channels ofmesoporousAl-MCM-41, and the product was characterized by X-ray diffraction, FTIR and BET analysis. It was found that size criteria prevented the complex to be incorporated in smaller cages of the LTA or NaY zeolites.Incorporation of the complex into the channels of Al-MCM-41, on the other hand,did not affected morphology of the host as it is evident from SEM micrographs.
    Keywords: [Fe(bipy)Cl4][bipy.H], Incorporation, Mesoporous, Al, MCM, 41
  • Reza Ojani, Fakhrosadat Jamali, Jahan, Bakhsh Raoof, Sayed Reza Hosseini Pages 33-40
    Copper nanoparticles were fabricated by electro-reduction of CuSO4solution in the presence of cetyltrimethylammonium bromide (CTAB) cationic surfactant as an additive through potentiostatic method. The prepared copper nanoparticles were characterized by scanning electron microscopy (SEM) and electrochemical methods. The SEM images reveal that the nanoparticles with diameters at about 70 nm were uniformly dispersed on the electrode surface. Copper oxide nanoparticles modified glassy carbon electrode (nano CuO/MGCE) was prepared by using consecutive potential cycling between -1.0 to 1.0V at 100mVs −1 in 0.1 M NaOH solution. The electrochemical techniques such ascyclic voltammetry and chronoamperometry showed that the nano CuO/MGCE can catalyze the methanol oxidation in 0.1 M NaOH solution. It has been found that in the course of an anodic potential sweep, the methanol oxidation follows the formation of CuIII and is catalyzed by this species through a mediated electron transfer. Also, the modified electrode was stable for three weeks in dry conditions after repetitive measurements.
    Keywords: Copper oxide nanoparticles, Electrocatalytic oxidation, Methanol, Cyclic voltammetry
  • Naz Chaibakhsh, M.B. Abdul Rahman, K. Jesunathan, M. Basri Pages 41-55
    Esterification of chitosan with adipic acid catalyzed by immobilized Candida antarctica lipase B was carried out in this study. Response surface methodology (RSM) based on a four factor- five-level small central composite design (SCCD) was employed to model and analyze the reaction. A total of 21 experiments representing different combinations of the four reaction parameters including chitosan concentration (0.01-0.10 g/mL), temperature (35-65◦C), time (15-240 min), and enzyme amount (5-20 % w/w of total substrate) were generated. A partial cubic equation was fitted to the data with a R2 of 0.9738 showing a high correlation between predicted and experimental values. The enzyme was capable of esterifying chitosan with a maximum yield of 45.3%. Chitosan concentration was found to be the most significant parameter which influenced the ester synthesis. At the optimal conditions of a short reaction time 15 min, 65oC, 0.10 g/mL of chitosan and 18.7% of enzyme, the esterification percentage was 43.5%.
    Keywords: Chitosan, Enzymatic synthesis, Esterification, modeling, Response surface methodology
  • Mojgan Zendehdel, M. Solimannejad Pages 57-63
    A computational study of the electronic structure and stability of complexes formed between Zeolite Y and boric acid was carried out at the HF and B3LYP levels using 6-31G* basis set. Five structures located as local minimum in PES of complex (structures d, e, f, g, and h). The most stable structure is formed due to hydrogen bonding between two hydroxyl of boric acid and both oxygen of AlO2 in Zeolite (structure e).
    Keywords: Zeolite Y, H3BO3, ab initio, DFT