Au-Based Catalysts: Electrochemical Characterization for Structural Insights

Pifferi, V.; Chan‐Thaw, Carine E.; Campisi, Sebastiano; Testolin, A.; Villa, Alberto; Falciola, L.; Prati, Laura

doi:10.3390/molecules21030261

Cited by 9 publications

(8 citation statements)

References 44 publications

(50 reference statements)

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“…Also in this case, the broad oxidation peak related to the reaction of the background is present in the PS fibers case, which covers the ones related to the metallic nanoparticles. In the case of LHT, it can be noticed the presence of two oxidation peaks at about +1.25 and +1.74 V (SCE) related to the Pd and Au oxide formation, respectively, both shifted at higher anodic potentials with respect to their monometallic components [45]. This behavior can be attributed to a stabilizing effect that the two metals exhibit when they are alloyed, as already evidenced in the literature [7].…”

Section: Electrochemical Characterizationsupporting

confidence: 61%

Cyclic Voltammetry Characterization of Au, Pd, and AuPd Nanoparticles Supported on Different Carbon Nanofibers

Testolin

Cattaneo

et al. 2019

Surfaces

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Three types of carbon nanofibers (pyrolytically stripped carbon nanofibers (PS), low-temperature heat treated carbon nanofibers (LHT), and high-temperature heat treated carbon nanofibers (HHT)) with different graphitization degrees and surface chemistry have been used as support for Au, Pd, or bimetallic AuPd alloy nanoparticles (NPs). The carbon supports have been characterized using Raman, X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Moreover, the morphology of the metal nanoparticles was investigated using transmission electron microscopy (TEM) and CV. The different properties of the carbon-based supports (particularly the graphitization degree) yield different electrochemical behaviors, in terms of potential window widths and electrocatalytic effects. Comparing the electrochemical behavior of monometallic Au and Pd and bimetallic AuPd, it is possible to observe the interaction of the two metals when alloyed. Moreover, we demonstrate that carbon surface has a strong effect on the electrochemical stability of AuPd nanoparticles. By tuning the Au-Pd nanoparticles’ morphology and modulating the surface chemistry of the carbon support, it is possible to obtain materials characterized by novel electrochemical properties. This aspect makes them good candidates to be conveniently applied in different fields.

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Section: Electrochemical Characterizationsupporting

confidence: 61%

Cyclic Voltammetry Characterization of Au, Pd, and AuPd Nanoparticles Supported on Different Carbon Nanofibers

Testolin

Cattaneo

et al. 2019

Surfaces

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“…In case of AuPd NPs the SPR characteristics of Au disappeared (Figure a). The results confirmed the formation of bimetallic nanoalloys as the disappearance of the SPR characteristics could be attributed to changes in the band structure of Au NPs on alloying with Pd . The XRD patterns of Au, Pd and bimetallic AuPd NPs (Figure b) exhibited two major diffraction peaks in the region 30° < 2θ < 70° that correspond to the (111) and (200) of the fcc structure of monometallic Au and Pd .…”

Section: Figurementioning

confidence: 98%

Compositional Effect in AuPd Bimetallic Nanoparticles Towards Product Selectivity during Aerobic Oxidation of α-Hydroxy Esters and Phosphonates

2016

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Aerobic oxidation of a-hydroxy esters and phosphonates for direct formation of a-keto esters and a-keto phosphonates was explored using Au nanoparticle based catalytic systems. Alloying Au with Pd resulted in high activity and selectivity for the aerobic oxidation reaction under base and solvent free conditions. The formation of desired a-keto esters and a-keto phosphonates as sole products were highly dependent on the composition of the alloy nanocatalyst. Addition of a secondary oxidizer such as tert-butylhydroperoxide (TBHP) significantly enhanced the yield of the products at shorter reaction time under mild reaction conditions.

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“…Finally, the electrochemical characterization (by cyclovoltammetry CV and electrochemical impedance spectroscopy EIS) of Au-Pd systems is reported to determine the presence of an electronic interaction between the two metals [9]. The higher activity of the AuPd bimetallic system in the liquid phase oxidation of glycerol is due to a compromise between the stability of the oxidic species (decreased with respect to Pd) and the facility of hydride formation (increased with respect to Au).…”

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confidence: 99%

“…Thus the most active samples are those with the highest proportion of singly charged gold ions, while materials with a high content of Au +3 are inactive at low-temperatures. Higher stabilization can be achieved through modification of TiO 2 with transition metals oxides (namely La 2 O 3 ).Finally, the electrochemical characterization (by cyclovoltammetry CV and electrochemical impedance spectroscopy EIS) of Au-Pd systems is reported to determine the presence of an electronic interaction between the two metals [9]. The higher activity of the AuPd bimetallic system in the liquid phase oxidation of glycerol is due to a compromise between the stability of the oxidic species (decreased with respect to Pd) and the facility of hydride formation (increased with respect to Au).…”

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confidence: 99%

Special Issue: Coinage Metal (Copper, Silver, and Gold) Catalysis

Carabineiro

2016

Molecules

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Abstract:The subject of catalysis by coinage metals (copper, silver, and gold) comes up increasingly day-by-day. This Special Issue aims to cover the numerous aspects of the use of these metals as catalysts for several reactions. It deals with synthesis and characterization of copper, silver and gold based catalysis, their characterization and use, both for heterogeneous and homogeneous catalysis, and some of their potential applications.Keywords: copper; silver; gold; catalysis; selectivity Catalysts are materials that allow important reactions to be more selective, faster and require less energy. Coinage metals (copper, silver, and gold) are often found as important components of most catalysts and are known for their high activity and important properties. Thus the demand for research on this topic is continuously increasing.This Special Issue aims to cover several aspects of the usage of Cu, Ag and Au as catalysts for both homogenous and heterogeneous catalysis. It consists of nine important "cutting-edge" open access papers available to all online.The role of sub-nanometric Ag species (on Fe, Mg and Ce modified TiO 2 materials) on catalytic CO oxidation is studied by several techniques in [1]. The observed phenomena cannot be explained only considering the 1-13 nm Ag particle size distributions measured by HRTEM; the existence of Ag species with size < 1 nm, non-visible in HRTEM, and their interaction with the supports, needs also to be taken into account.Silver and copper are reported as catalysts, in a new and efficient way, for the cycloaddition of propargyl-substituted dihydroisoindolin-1-one with arylnitrile oxides to produce novel 3,5-disubstituted isoxazoles of the ethyl-2-benzyl-3-oxo-1-((3-arylisoxazol-5yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylate type [2]. Yields are significantly improved with the presence of Cu I as catalyst compared to the uncatalyzed reaction, without changing the selectivity.Aroylhydrazone Cu(II) complexes in keto form are reported as catalysts for the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, under mild conditions [3]. The activity exhibited by those complexes in the absence of any additive, is higher than that shown by other efficient Cu II systems reported in the literature.Copper is also used as a catalyst, deposited on different lanthanide-doped cerium oxides (Ce 0.5 Ln 0.5 O 1.75 , where Ln: Gd, La, Pr, Nd) for the oxidation of ethyl acetate, a harmful volatile organic compound [4]. The best catalytic performance was obtained for Cu/CeO 2 and Cu/Ce 0.5 Pr 0.5 O 1.75 samples. A strong correlation was found between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability.Gold incorporated on a mesoporous silica thin film is reported as a robust surface enhanced Raman scattering (SERS) and catalytically active substrate for the reduction of p-nitrophenol to p-aminophenol [6]. This material might offer a promising eco-friendly way for the product...

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Au-Based Catalysts: Electrochemical Characterization for Structural Insights

Cited by 9 publications

References 44 publications

Cyclic Voltammetry Characterization of Au, Pd, and AuPd Nanoparticles Supported on Different Carbon Nanofibers

Cyclic Voltammetry Characterization of Au, Pd, and AuPd Nanoparticles Supported on Different Carbon Nanofibers

Compositional Effect in AuPd Bimetallic Nanoparticles Towards Product Selectivity during Aerobic Oxidation of α-Hydroxy Esters and Phosphonates

Special Issue: Coinage Metal (Copper, Silver, and Gold) Catalysis

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