Gold nanoparticle-decorated graphene oxide: Synthesis and application in oxidation reactions under benign conditions (original) (raw)
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Energies
The commonly used electrode Pt supported on a carbon (Pt/C) catalyst has demonstrated underperforming electrochemical durability in proton exchange membrane fuel cell (PEMFC) harsh operation conditions, especially in terms of Pt electrochemical instability and carbon corrosion. Gold nanoparticles (AuNPs) are considered one of the best alternative catalysts of PtNPs due to their remarkable selectivity for oxygen reduction reaction (ORR) and electrochemical stability in strong acid conditions, attributes which are ideal for practical PEMFC applications. In this work, we propose a new, facile and low-cost approach to prepare AuNPs supported on reduced graphene oxide nanocompounds (AuNPs/rGO). The morphological and structural properties of the as-prepared AuNPs/rGO were studied using various microscopic and spectroscopic techniques, namely, Raman Spectroscopy, Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), X-Ray Diffraction (XRD), Fourier Transform...
DOAJ (DOAJ: Directory of Open Access Journals), 2011
The myth that gold cannot act as a catalyst has been discarded in view of recent studies, which have demonstrated the high catalytic efficiency of pure nano-gold and supported nano-gold catalysts. In recent years, numerous papers have described the use of supported nano-gold particles for catalysis in view of their action on CO and O 2 to form CO 2 , as well as a variety of other reactions. Special emphasis is placed on the oxidation studies undertaken on model nano-Au systems. In this work a solvent free oxidation of 1-phenyl ethanol was carried out using gold supported on ceria-silica, ceriatitania, ceria-zirconia and ceria-alumina at 160 0 C. Almost 88-97% conversion was obtained with >99% selectivity. Temperature screening was done from 70 to 160 0 C.Catalysts were prepared by deposition co-precipitation method and deposition was determined by EDEX analysis.
Synthesis of Supported Gold Nanocatalysts for the Oxidation of Alkyl Benzenes
Advanced Materials Research, 2015
Selective oxidation of alkyl benzene, to its corresponding oxygen containing products, is a crucial reaction in organic researches and industrial manufacturing. In particular, the direct oxidation of lavish and cheapest aromatics, having carbon-hydrogen bonds, into corresponding ketones are the key transformations as the oxidation products are very important platform compounds for the production of useful prime, special chemicals and high economic valued fine chemicals, agrochemicals, pharmaceutical and perfumes in large scale. However, the oxidations of aromatic hydrocarbons have been remaining a challenging task due to the limitations of a suitable catalyst and requirement of chemical treatments (potassium permanganate/dichromate and ammonium cerium nitrate) which have been proven to be corrosive, not reusable, hazardous, and environmentally unfriendly and, also, have no selectivity at all. Instead of, scientists are paying more attention to use heterogeneous green catalysts along with support as well as novel oxidants e.g. hydrogen peroxide, tert-butyl peroxide and so on, due to its ecofriendly nature and availability. Silica/carbon/metal oxide supported nanoporous gold is a favorable catalyst due to its three dimensional open pore network structures, high surface to volume ratio, high reusability, distinct optolectronic and physio-chemical properties. Mesoporous carbon/silica/metal oxide supports provide well scattering of metal nanocatalysts and facilitate the transportation of molecules through the nanopores/nanochannels, thus increase the product with lowest cost and time. This paper has reviewed various gold-skeleton green catalysts and their synthetic method and mechanistic schemes for the selective oxidation of alkyl substituted aromatics.
The myth that gold cannot act as a catalyst has been discarded in view of recent studies, which have demonstrated the high catalytic efficiency of pure nano-gold and supported nano-gold catalysts. In recent years, numerous papers have described the use of supported nano-gold particles for catalysis in view of their action on CO and O 2 to form CO 2 , as well as a variety of other reactions. Special emphasis is placed on the oxidation studies undertaken on model nano-Au systems. In this work a solvent free oxidation of 1-phenyl ethanol was carried out using gold supported on ceria-silica, ceriatitania, ceria-zirconia and ceria-alumina at 160 0 C. Almost 88-97% conversion was obtained with >99% selectivity. Temperature screening was done from 70 to 160 0 C.Catalysts were prepared by deposition co-precipitation method and deposition was determined by EDEX analysis.
Electrochimica Acta, 2013
A crystalline composite nanostructure based on graphene and gold nanoparticles (denoted as Gr-Au) was synthesized in a single-step process by Radio Frequency catalytic Chemical Vapour Deposition (RF-cCVD) over an Au x /MgO catalytic system (where x = 3 wt.% and represents the amount of metal loaded in the catalyst). After preparation, the composite was chemically oxidized with a mixture of sulfuric/nitric acid (3:1 vol.), being subsequently denoted as Gr-Au OH. No massive exfoliation of graphene layers occurred during oxidation, so the degree of crystallinity was preserved, as proved by X-ray powder diffraction (XRD) measurements. For both samples, the crystalline domain had a mean value of approximately 2.25 nm, corresponding to about 6 graphitic layers. The electro-catalytic properties of Gr-Au and Gr-Au OH composites were tested by modifying two gold electrodes with the same amount of each material (denoted Au/Gr-Au and Au/Gr-Au OH, respectively) and subsequently employed for the electrochemical analysis of guanine. A significant decrease in the electrochemical oxidation potential of guanine (∼100 mV) was obtained in both cases. Tafel analysis proved that the modified electrodes have a large value for the exchange current density (approximately 10 −7 A) which is one order of magnitude larger than that corresponding to a bare gold electrode. Consequently, these composite materials greatly enhance the transfer of electrons from solution to electrode. However, the major drawback of the Gr-Au OH nanostructure is the large capacitive current induced by the oxygen functional groups and observed in all cyclic voltammetric measurements, which considerably diminishes the sensitivity of the modified electrode.
2011
The myth that gold cannot act as a catalyst has been discarded in view of recent studies, which have demonstrated the high catalytic efficiency of pure nano-gold and supported nano-gold catalysts. In recent years, numerous papers have described the use of supported nano-gold particles for catalysis in view of their action on CO and O 2 to form CO 2 , as well as a variety of other reactions. Special emphasis is placed on the oxidation studies undertaken on model nano-Au systems. In this work a solvent free oxidation of 1-phenyl ethanol was carried out using gold supported on ceria-silica, ceriatitania, ceria-zirconia and ceria-alumina at 160 0 C. Almost 88-97% conversion was obtained with >99% selectivity. Temperature screening was done from 70 to 160 0 C.Catalysts were prepared by deposition co-precipitation method and deposition was determined by EDEX analysis.
2011
The myth that gold cannot act as a catalyst has been discarded in view of recent studies, which have demonstrated the high catalytic efficiency of pure nano-gold and supported nano-gold catalysts. In recent years, numerous papers have described the use of supported nano-gold particles for catalysis in view of their action on CO and O 2 to form CO 2 , as well as a variety of other reactions. Special emphasis is placed on the oxidation studies undertaken on model nano-Au systems. In this work a solvent free oxidation of 1-phenyl ethanol was carried out using gold supported on ceria-silica, ceriatitania, ceria-zirconia and ceria-alumina at 160 0 C. Almost 88-97% conversion was obtained with >99% selectivity. Temperature screening was done from 70 to 160 0 C.Catalysts were prepared by deposition co-precipitation method and deposition was determined by EDEX analysis.
2017
Pyrolysis of chitosan films containing Au 3+ renders 1.1.1 oriented Au nanoplatelets (20 nm lateral size, 3-4 nm height) on few layers N-doped graphene (Au ̅̅̅̅ /fl-G), while the lateral sides were 0.0.1 oriented. Comparison of the catalytic activity of Au ̅̅̅̅ /fl-G films with powders of unoriented Au NPs supported on few layer graphene showed that Au ̅̅̅̅ /fl-G films exhibit six orders of magnitude enhancement for three Au-catalyzed reactions, namely, the Ullmannlike homocoupling, the C-N cross coupling and the oxidative coupling of benzene to benzoic acid as result of the defined morphology, facet orientation of Au nanocrystals and strong Augraphene interaction. Catalysis by supported metal nanoparticles (MNPs) has been a very active field of research in the last thirty years. Remarkable examples of highly active and selective MNP catalysts for organic transformations including aerobic oxidations, couplings and rearrangements have been reported. Catalysis by gold constitutes one ...
Applied Surface Science, 2019
A facile approach for preparation of gold nanoparticles decorated on reduced graphene oxide (AuNPs/rGO) in mild reaction conditions is described. Several microscopic and spectroscopic techniques (SEM, FTIR, XPS) have been connected with structural investigation (BET) in order to confirm the successful synthesis of AuNPs/rGO nanocomposites. The end application of AuNPs/rGO in proton exchange membrane fuel cells (PEMFC) has been considered as innovative nanomaterial for oxygen reduction reaction (ORR). In this respect, the electrochemical techniques were involved for a comprehensive in-situ characterization of developed ORR catalysts, in particular the durability has been assessed in order to evaluate the long-term performance. The structural characteristics and their synergistic effects could not only improve the ions and electrons transportation but also enhance the electrochemical stability in acid medium specific for PEMFC. The electrode containing AuNPs/rGO presented superior electrochemical performances as along with the long-term stability, demonstrating a considerable potential as efficient ORR catalytic material.