Mechanism for the Electrocatalyzed Oxidation of Glycerol Deduced from an Analysis of Chemical Instabilities

Schell, Mark; Xu, Yan; Zdraveski, Zoran

doi:10.1021/jp961195t

Cited by 41 publications

(30 citation statements)

References 25 publications

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“…DAFCs provide the possibility of generating energy from the waste. The mechanism of electrochemical oxidation of glycerol in alkaline solution was investigated by Roquet et al and Schell et al [38,39]. Glyceraldehyde was found to be the main reaction product, but formic, glycolic, tartronic and glyceric acids were also detected [38].…”

Section: Principles and Mechanisms Of A Direct Alkaline Alcohol Fuel mentioning

confidence: 99%

Principles and Materials Aspects of Direct Alkaline Alcohol Fuel Cells

2010

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Direct alkaline alcohol fuel cells (DAAFCs) have attracted increasing interest over the past decade because of their favourable reaction kinetics in alkaline media, higher energy densities achievable and the easy handling of the liquid fuels. In this review, principles and mechanisms of DAAFCs in alcohol oxidation and oxygen reduction are discussed. Despite the high energy densities available during the oxidation of polycarbon alcohols they are difficult to oxidise. Apart from methanol, the complete oxidation of other polycarbon alcohols to CO 2 has not been achieved with current catalysts. Different types of catalysts, from conventional precious metal catalyst of Pt and Pt alloys to other lower cost Pd, Au and Ag metal catalysts are compared. Non precious metal catalysts, and lanthanum, strontium oxides and perovskite-type oxides are also discussed. Membranes like the ones used as polymer electrolytes and developed for DAAFCs are reviewed. Unlike conventional proton exchange membrane fuel cells, anion exchange membranes are used in present DAAFCs. Fuel cell performance with DAAFCs using different alcohols, catalysts and membranes, as well as operating parameters are summarised. In order to improve the power output of the DAAFCs, further developments in catalysts, membrane materials and fuel cell systems are essential. OPEN ACCESSEnergies 2010, 3 1500

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Section: Principles and Mechanisms Of A Direct Alkaline Alcohol Fuel mentioning

confidence: 99%

Principles and Materials Aspects of Direct Alkaline Alcohol Fuel Cells

2010

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“…Schell et al [156] have studied the electrocatalyzed oxidation of glycerol in alkaline solution upon cyclic variation of the polycrystalline Pt electrode potential and compared it with the oxidations of ethylene glycol and methanol. Based on analysis of behaviors caused by chemical instabilities, the conclusion was drawn that the elementary reactions that dominate the oxidation of glycerol are the same as those that dominate the oxidation of methanol, including the formation of surface bonded CO and its reaction with surface bonded hydroxyl radicals.…”

Section: Other Oscillatory Oxidation Reactionsmentioning

confidence: 99%

Temporal Instabilities in Anodic Oxidation of Small Molecules/Ions at Solid Electrodes

Orlik

2012

Monographs in Electrochemistry

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Oscillations and multistability in oxidation processes at solid electrodes are important for several reasons. First, they were reported for species that are (or can appear) important in chemical engineering of fuels, including the fuel cells: hydrogen, carbon monoxide, formaldehyde, formic acid/formate ions, 2-propanol, 1-butanol, hydrazine, or ethylene glycol. It can be useful to know how to avoid instabilities involving these species or, on the contrary, to profit from them. Second, electrooxidation of these molecules exhibits rich variety of nonlinear dynamic behaviors which can be treated in a model way for the sake of generalization. Third, some of these processes, under appropriate conditions, can become a source of spatial or spatiotemporal patterns on electrodes which phenomena only recently gained satisfactory explanation and description. In this chapter, we shall summarize the temporal phenomena associated with the oxidation of the above-mentioned molecules, while pattern formation will be discussed in separate Chap. 2 of volume II.Current research data indicate that such processes should be qualified as electrocatalytic, i.e., the electrode surface is actively engaged in the kinetics of the electron transfer reaction, usually involving the process taking place via the adsorbed intermediate. As in the case of other types of electrochemical oscillators, one can observe the evolution of the understanding of the source of chemical instabilitiesfrom early, sometimes oversimplified explanations oriented exclusively on the properties of the electrode/electrolyte interface toward more recent concepts, involving the analysis of the system's stability in terms of nonlinear dynamics. In particular, oscillations under galvanostatic conditions could be understood only recently in terms of the concept of the HN-NDR oscillator [1] (cf. Chap. 3).The anodic oxidation of H 2 on Pt electrode is an electrocatalytic process, in which the electron transfer is preceded by the adsorption of H 2 molecule on the active surface site. Hence, the oscillatory course of this process can be associated M. Orlik, Self-Organization in Electrochemical Systems I, Monographs in Electrochemistry,

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“…Strong adsorbed intermediates, surface passivation by (hydro)oxide and changes in surface roughness are possible candidates to act, inhibiting active sites and decreasing the current. 13,15,16 The presence of HOV during H 2 electrooxidation and constant mass changes measured by electrochemical quartz crystal microbalance during methanol oxidation on Pt 15 suggest no accumulation of intermediates along the cycles. Despite several advances in understanding HOV, most studies focus on Pt as catalyst and, to our knowledge, there is only one paper reporting the effect in Pd.…”

Section: Introductionmentioning

confidence: 99%

High Order Cyclic Voltammograms During Electrooxidation of Ethanol Catalyzed by Gold

Silva¹,

Maruyama²,

Sitta³

2017

J. Braz. Chem. Soc.

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Under fixed limits, potential sweeps in some electrochemical systems depict current profile whose shape repeats in every n cycle (with n > 1), receiving the name of high order voltammograms (HOV). HOV have been observed during electrooxidation of organic molecules catalyzed mainly by Pt. The present study shows HOV behavior during ethanol electrooxidation reaction onto gold in alkaline media. Firstly, a strong dependence of HOV with minimum potential is remarkable in this system and has not been considered in previous numeric models. Moreover, due to high sensibility of HOV to surface conditions, it was possible to follow effects caused by cation interactions with adsorbed oxygenated species. Keywords: high order voltammograms, ethanol electrooxidation, gold catalyst, cation effects IntroductionIn a conventional cyclic voltammetry experiment the applied potential is continuously changed at a fixed rate between two limits (E min and E up ) while the current is registered. 1 The characteristic current-potential plot is called cyclic voltammogram and the current value at a given potential and scan direction can depict three behaviors: it becomes unchanged along the cycles; increase or decrease monotonically along the cycles; repeat its profile every set of cycles, that can be periodic, i.e., observed in every n cycle (n > 1) or aperiodic, in which n admits more than one value along the experiment. These voltammograms, periodic or aperiodic, are called high order voltammograms (HOV) and in contrast to the other cases, they are much less explored in the electrochemical field.Examples of HOV can be found for several small organic molecules electrooxidation reactions catalyzed by Pt in both alkaline and acid media. [2][3][4][5][6][7][8][9][10][11] Varela and Krischer 12,13 also found HOV during electrooxidation of hydrogen in acid media. In any case, two conditions are necessary to observe HOV: the reaction should contain an inhibition region at high overpotential, in general connected with oxide formation, giving origin to a peak current; an expressive ohmic drop, given by the product of current (I) and resistance (R), provided by low concentration supporting electrolyte or an external resistance.Ohmic drop allows the separation of applied potential (E) and the potential at interphase (ϕ) once E = ϕ + IR.14 When E up is set slightly more negative than the potential of peak current, the first cycles have almost the same current during positive and negative going scans, (small hysteresis) being classified as S cycles, but along the cycles, the current decreases and ϕ becomes higher and higher until reaching the region of current inhibition. At this point, ϕ quickly increases and oxides cover the surface. This condition makes the current in the negative going scan very distinct from that in the positive, i.e., with a large hysteresis and the cycle being classified as L. If the cycle after the L is the S, the initial condition is restored and the HOV is observed. 15 Indeed, to observe HOV the system should contain some pa...

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Mechanism for the Electrocatalyzed Oxidation of Glycerol Deduced from an Analysis of Chemical Instabilities

Cited by 41 publications

References 25 publications

Principles and Materials Aspects of Direct Alkaline Alcohol Fuel Cells

Principles and Materials Aspects of Direct Alkaline Alcohol Fuel Cells

Temporal Instabilities in Anodic Oxidation of Small Molecules/Ions at Solid Electrodes

High Order Cyclic Voltammograms During Electrooxidation of Ethanol Catalyzed by Gold

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