Catalysts2015, 5(4), 1657-1672; doi:10.3390/catal5041657 - published 5 October 2015 Show/Hide Abstract
Abstract: Indole-6-carboxylic acid (ICA) and 3,4-ethylenedioxythiophene (EDOT) are copolymerized electrochemically on a stainless steel (SS) electrode to obtain poly(indole-6-carboxylic acid-co-3,4-ethylenedioxythiophene)s (P(ICA-co-EDOT))s. The morphology of P(ICA-co-EDOT)s is checked using scanning electron microscopy (SEM), and the SEM images reveal that these films are composed of highly porous fibers when the feed molar ratio of ICA/EDOT is greater than 3/2. Platinum particles can be electrochemically deposited into the P(ICA-co-EDOT)s and PICA films to obtain P(ICA-co-EDOT)s-Pt and PICA-Pt composite electrodes, respectively. These composite electrodes are further characterized using X-ray photoelectron spectroscopy (XPS), SEM, X-ray diffraction analysis (XRD), and cyclic voltammetry (CV). The SEM result indicates that Pt particles disperse more uniformly into the highly porous P(ICA3-co-EDOT2) fibers (feed molar ratio of ICA/EDOT = 3/2). The P(ICA3-co-EDOT2)-Pt nanocomposite electrode exhibited excellent catalytic activity for the electrooxidation of methanol in these electrodes, which reveals that P(ICA3-co-EDOT2)-Pt nanocomposite electrodes are more promising for application in an electrocatalyst as a support material.
Catalysts2015, 5(4), 1649-1656; doi:10.3390/catal5041649 - published 25 September 2015 Show/Hide Abstract
Abstract: A novel and green approach for efficient and rapid synthesis of 4-aryl-3-methyl-1-phenyl-1H-benzo[h]pyrazolo[3,4-b]quinoline-5,10-diones has been accomplished by the one-pot condensation reaction of aromatic aldehydes, 3-methyl-1-phenyl-1H-pyrazol-5-amine and 2-hydroxynaphthalene-1,4-dione using PEG1000-based dicationic acidic ionic liquid (PEG1000-DAIL) as a catalyst was reported. Recycling studies have shown that the PEG1000-DAIL can be readily recovered and reused several times without significant loss of activity. The key advantages are the short reaction time, high yields, simple workup, and recovered catalyst.
Catalysts2015, 5(4), 1636-1648; doi:10.3390/catal5041636 - published 25 September 2015 Show/Hide Abstract
Abstract: The kiwifruit industry is booming worldwide. As a result, a great deal of kiwifruit waste residue (KWR) containing monosaccharides is produced and discarded. This material shows great potential for the production of platform chemicals. In this study, a series of Nb/Al oxide catalysts were synthesized via a facile and low-cost coprecipitation method, and their structures were characterized using: thermal gravimetric analysis (TGA), XRD, FESEM, TEM, X-ray photoelectron spectroscopy (XPS), NH3-TPD, N2 adsorption-desorption, and FTIR-Pyridine adsorption. Experimental results of sugar-to-levulinic acid (LA) conversion revealed that the 20%Nb/Al oxide catalyst provided the highest catalytic performance and durability in terms of LA yield from fructose (74.2%) at 463 K after 10 min and from glucose (47.5%) at 473 K after 15 min. Notably, the 20% Nb/Al oxide catalyst with a 10% dosage is capable of converting kiwifruit waste residue to LA at 473 K after 10 min. In conclusion, the enhanced catalytic performance was obtained due to the high acidity, and large surface areaof Nb/Al oxide catalyst.
Catalysts2015, 5(3), 1622-1635; doi:10.3390/catal5031622 - published 21 September 2015 Show/Hide Abstract
Abstract: Carbon graphitic structures that differ in morphology, graphiticity and specific surface area were used as support for platinum for Oxygen Reduction Reaction (ORR) in low temperature fuel cells. Graphitic supports were first non-covalently functionalized with pyrene carboxylic acid (PCA) and, subsequently, platinum nanoparticles were nucleated on the surface following procedures found in previous studies. Non-covalent functionalization has been proven to be advantageous because it allows for a better control of particle size and monodispersity, it prevents particle agglomeration since particles are bonded to the surface, and it does not affect the chemical and physical resistance of the support. Synthesized electrocatalysts were characterized by electrochemical half-cell studies, in order to evaluate the Electrochemically Active Surface Area (ECSA), ORR activity, and durability to potential cycling and corrosion resistance.
Catalysts2015, 5(3), 1603-1621; doi:10.3390/catal5031603 - published 18 September 2015 Show/Hide Abstract
Abstract: Titania containing cubic MCM-48 mesoporous materials were synthesized successfully at room temperature by a modified Stöber method. The integrity of the cubic mesoporous phase was retained even at relatively high loadings of titania. The TiO2-MCM-48 materials were extensively characterized by a variety of physico-chemical techniques. The physico-chemical characterization indicate that Ti4+ ions can be substituted in framework tetrahedral positions. The relative amount of Ti4+ ions in tetrahedral position was dependent on the order of addition of the precursor. Even at relatively high loadings of titania, no distinct bulk phase of titania could be observed indicating that the titania nanoclusters are well dispersed on the high surface area mesoporous material and probably exist as amorphous nanoclusters. The TiO2-MCM-48 materials were found to exhibit 100% selectivity in the cyclohexene oxidation at room temperature in the presence of tert-butylhydroperoxide (t-BHP) as the oxidant. The results suggest that room temperature synthesis is an attractive option for the preparation of TiO2-MCM-48 materials with interesting catalytic properties.
Catalysts2015, 5(3), 1574-1602; doi:10.3390/catal5031574 - published 14 September 2015 Show/Hide Abstract
Abstract: Nitrogen-doped carbon materials, includingnitrogen-dopedcarbon nanotubes (NCNTs) and nitrogen-doped graphene (NG), have attracted increasing attention for oxygen reduction reaction (ORR) in metal-air batteries and fuel cell applications, due to their optimal properties including excellent electronic conductivity, 4e− transfer and superb mechanical properties. Here, the recent progress of NCNTs- and NG-based catalysts for ORR is reviewed. Firstly, the general preparation routes of these two N-doped carbon-allotropes are introduced briefly, and then a special emphasis is placed on the developments of both NCNTs and NG as promising metal-free catalysts and/or catalyst support materials for ORR. All these efficient ORR electrocatalysts feature a low cost, high durability and excellent performance, and are thus the key factors in accelerating the widespread commercialization of metal-air battery and fuel cell technologies.