Glycerol oxidation reaction using PdAu/C electrocatalysts (original) (raw)
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International Journal of Hydrogen Energy, 2015
The catalytic activity and stability of electrodeposited PdeCo alloy layers on Au electrode was evaluated for glycerol oxidation reaction (GOR) in an alkaline solution. The morphology and structural characteristics of the Pd and PdeCo alloy were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The electro-oxidation of glycerol on the Pd/Au and PdeCo/Au was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques. By varying Co concentration in the deposition solution, it was demonstrated that the Pd (61%)-Co (4%) catalyst [denoted PdeCo(3)/Au] has the highest electrocatalytic activity. Obtained results showed that the PdeCo(3)/Au has the excellent activity in terms of the specific peak current density and onset potential compared to pure Pd for oxidation of glycerol. For PdeCo (3)/Au, the onset potential shifts to negative values by 80 mV compared to the onset potential of Pd/Au. The stability tests indicated that the presence of Co has a significant effect on the poisoning tolerance of the Pd toward glycerol electrooxidation. Form the obtained results; one can conclude that the PdeCo alloy exhibits suitable activity as a promising catalyst for alcohol electro-oxidation reactions in fuel cells.
Electrochemical Reaction and Dissociation of Glycerol on PdAu Surface Catalyst
Sains Malaysiana, 2020
Direct Glycerol Fuel Cell is one of the alternative energy that can produce electricity without burning. The production of electricity without combustion can reduce the use of fossil fuel as well as reduce environmental pollution. A new catalyst of PdAu has been synthesized in this study to increase the activity of the glycerol oxidation reaction. Morphologies analysis was performed on CNF-supported synthesized PdAu. FESEM and TEM image show the PdAu supported on the CNF surface. Both PdAu and CNF has a diameter size of 4-6 nm and 80-130 nm, respectively. In CV analysis, PdAu/CNF has produced an oxidation peak and current density at -0.9 V vs. SCE and 70 mA/cm2, respectively. Each mechanism of glycerol dissociation step during glycerol oxidation, different atomic active sites are required in PdAu. For example, for glycerol adsorption, Au atom as an active site while for *C3H7O3 requires Pd atom and Au atom as the active site. The Au catalyst model shows better adsorption as Au/CNF h...
The Journal of Chemical Physics, 2019
The catalytic effect of Pd on gold electrodes for glycerol oxidation is evaluated for Pd-Au surfaces prepared using three different methods: irreversible adsorption of palladium by a simple immersion of a gold electrode in palladium solution, the deposition of palladium on the gold substrate by a step potential from 1 to 0.75 V, and the forced deposition of palladium on the gold electrode with the help of a reducing hydrogen atmosphere. Voltammetry has been used for the electrochemical characterization of the Pd-Au deposits and to determine its reactivity towards glycerol oxidation, whereas FTIR experiments have allowed detecting adsorbed species and products formed during the oxidation reaction. Pd-Au surfaces prepared by irreversible adsorption are the electrodes that show the highest activity for the glycerol complete oxidation to carbonate, whereas Pd-Au surfaces made by the step potential are the catalyst that exhibits the highest rate for the formation and adsorption CO before carbonate production, poisoning the surface and diminishing their electrocatalytic properties. In addition to carbonate, glycerate, glycolate, and formate are detected as oxidation products. The integrated bands of the spectra are used to give quantitative information for comparing the product distribution of the different Pd-Au deposits prepared.
Catalysts
Ceria-supported Pd catalysts encompassing oxides of Cu, Co, and Fe were synthesized and characterized using XRD, TEM, SEM-EDX, TPR, BET, and Raman. After the incorporation of the metal oxides, the surface area and pore volume of the ceria support decreased. XRD showed the presence of the metal oxide phases as well as the support, CeO2. TPR showed that the bimetallic catalyst had improved reducibility compared to the monometallic Pd/CeO2. TEM images showed irregular-shaped particles with an average size distribution of 2–10 nm. SEM-EDX showed that the metal oxides were evenly distributed over the surface of the support. The electro-oxidation of glycerol in an alkaline environment was evaluated using cyclic voltammetry, and the products formed were identified and quantified using GC-MS. Glyceric acid was the dominant product over Pd-CuO/CeO2, while glyceraldehyde and dihydroxyacetone were dominant over Pd-Co3O4/CeO2 and Pd-Fe2O3/CeO2, respectively.
Malaysian Journal of Analytical Science, 2017
In this study, Aurum (Au) was used as the second metal in palladium catalyst (Pd) and carbon nanofiber (CNF) as catalyst support for glycerol oxidation. Second metal and catalyst support will help to improve catalytic activity and decrease adsorbed oxidation intermediates species. Carbon nanofiber supported PdAu nanoparticles was synthesized by using trisodium citrate as stabilizing agent and sodium borohydride as reducing agent. Physicochemical characterizations of the catalyst were performed by X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscope (FESEM) and Brunauer-Emmett-Teller (BET) to study the nature of the catalysts. The electrochemical activity for oxidation of glycerol on PdAu/CNF was evaluated in half cell under alkaline media by cyclic voltammetry potentiostat. The densities and mass activity obtained from half-cell analysis were 73.81 mA cm-2 @ 492.04 mA mg-1 , 63.82 mA cm-2 @ 425.44 mA mg-1 and 55.73 mA cm-2 @ 371.54 mA mg-1 for PdAu/CNF, Pd/CNF and Au/CNF, respectively in 1 M KOH + 0.5 M glycerol electrolyte. The electrochemical study, exhibited the superior performance of bimetallic PdAu/CNF catalyst as compared to monometallic Pd/CNF. This indicate that the electronic coupling between Pd and Au can promote the electrocatalytic activity for glycerol oxidation.
Catalysts
This study investigates the most effective electrocatalyst for glycerol oxidation reaction (GOR) in alkaline medium for five synthesized electrocatalysts, Pd, PdNi, PdNiO, PdMn3O4 and PdMn3O4NiO, supported on multi-walled carbon nanotubes (MWCNTs) prepared using the polyol method. The particle size and crystalline size of the electrocatalysts were determined using HR-TEM and XRD techniques, respectively, while EDS was used to determine the elemental composition. XRD showed crystalline sizes ranging from 3.4 to 10.1 nm, while HR-TEM revealed particle sizes within the range of 3.4 and 7.2 nm. The electroactivity, electron kinetics and stability of the electrocatalysts towards glycerol in alkaline medium was evaluated using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA), respectively, while the electroactive surface area (ECSA) of the electrocatalysts was determined using cyclic voltammetry (CV). The metal oxide-based Pd electroc...
Applied Catalysis B: Environmental, 2011
Effects toward electrocatalytic activity for glycerol oxidation of the modification of carbon supported Pd and Pt-based nanomaterials by bismuth were evaluated in alkaline medium. Pd/C, Pd 0.9 Bi 0.1 /C, Pt/C, Pt 0.9 Bi 0.1 /C and Pd 0.45 Pt 0.45 Bi 0.1 /C catalysts were synthesized by a colloidal route, and physical and electrochemical methods were used to characterize the structure and the surface of the catalysts (TEM, HRTEM, EDX, XRD, ICP-OES and XPS). It was shown that only a few amount of bismuth was deposited on the Pt and/or Pd surface, and that no alloy was formed between bismuth and the other metals. The onset potential of glycerol oxidation is ca. 0.15 V lower on Pt/C than on Pd/C. However, Pt-free Pd 0.9 Bi 0.1 /C catalyst presented the same catalytic activity than platinum catalyst. The Pt 0.9 Bi 0.1 /C led reaching a higher catalytic activity by shifting the oxidation onset potential by ca. 0.2 V toward lower potentials compared with the Pt/C catalyst. But, the replacing of half of the platinum atoms by palladium atoms in the Pd 0.45 Pt 0.45 Bi 0.1 /C material allowed achieving the same catalytic activity as with Pt 0.9 Bi 0.1 /C. Electrochemical experiments combined with in situ infrared spectroscopy measurements have shown that glycerol electrooxidation mechanism is independent on the catalyst, but dependent on the electrode potential. Chronoamperometry experiments combined with HPLC measurements showed that the main reaction products were glycerate, dihydroxyacetone and tartronate at low potentials, and that the increase of the electrode potential led to the formation of mesoxalate. For potential higher than 0.8 V vs RHE, the C-C bond cleavage occurred and oxalate and formiate were detected.
Electroanalysis, 2021
Pd-In/C electrocatalysts were synthesized by the adapted borohydride reduction method in different atomic ratios. Electrocatalysts were evaluated by conventional electrochemical techniques and direct glycerol fuel cells. X-ray diffraction profiles indicated the structure of Pd and In (fcc) phases, as well as the presence of In higher oxidation states. Regarding Transmission electron microscopy, it showed the particle's average diameters between 6.1-12.7 nm. All PdIn/C electrocatalysts showed high current values for-0.30 V vs. Ag/AgCl, which the best one was PdIn/C 90:10. Higher performance for glycerol oxidation was observed in polarization curves at 90°C for PdIn/C (30:70) composition.