A switch effect in the oxidation behaviour of formate on Pt in alkaline solution caused by a differential pH change

Wetzel, R.; Günther, Helmut; Müller, Lothar

doi:10.1016/s0022-0728(79)80449-0

Cited by 7 publications

(8 citation statements)

References 14 publications

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“…This result demonstrates that the high 6 current density appear in the pH 6.9 unbuffered solution. The 7 CV characteristics are in good agreement with the recently 8 published report. 15,16 According to Reference 16, the peak 9 oxidation current (p3) observed at pH near 6 and its current 10 remained constant for pH greater than 6, except in the pres-11 ence of strong alkaline media.…”

supporting

confidence: 91%

Influence of Solution pH on Pt Anode Catalyst in Direct Formic Acid Fuel Cells

et al. 2015

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Formic acid has great potential for use as fuel in direct formic acid fuel cells (DFAFC). Because the catalytic activity of Pt for formate oxidation is sluggish in alkaline media, researchers have focused on using acid media in DFAFC technology. Recently, Osawa’s group demonstrated that the best reaction performance can be achieved at pH ≈ pK a. A systematic investigation of the HCOOH/HCOO– oxidation in an actual single cell over a wide pH range has not yet been performed. Here, single-cell experiments confirm the direct formate pathway in HCOOH/HCOO– oxidation, which leads to better oxidation kinetics at the optimal pH.

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confidence: 91%

Influence of Solution pH on Pt Anode Catalyst in Direct Formic Acid Fuel Cells

et al. 2015

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“…The pH 5.7 acetate buffer was found to yield high current densities for HCOOH oxidation, while H 2 SO 4 relates to fuel cell electrolytes. The current density for the electrocatalytic oxidation of formate at Pt under alkaline conditions is known to be relatively low [32] and so NaOH solutions were not investigated. eter Pt macroelectrode resembles the behaviour widely reported in the literature, [7,21,33] with the anodic scan displaying an oxidation peak centred at ca.…”

Section: Electrochemistry Of Formic Acidmentioning

confidence: 99%

“…The pH 5.7 acetate buffer was found to yield high current densities for HCOOH oxidation, while H 2 SO 4 relates to fuel cell electrolytes. The current density for the electrocatalytic oxidation of formate at Pt under alkaline conditions is known to be relatively low [32] and so NaOH solutions were not investigated. Figure 3 displays cyclovoltammograms (CVs) recorded for three Pt electrodes in a 1.0 m NaClO 4 solution containing 100 mm [NH 4 ][HCOO].…”

Section: Electrochemistry Of Formic Acidmentioning

confidence: 99%

Towards Mixed Fuels: The Electrochemistry of Hydrazine in the Presence of Methanol and Formic Acid

Aldous

Compton

2011

ChemPhysChem

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The electrochemistry of formic acid, carbon monoxide and methanol have been investigated and evaluated in combination with hydrazine. Hydrazine was observed to display the anticipated steady-state oxidation waves at platinum (Pt) microelectrodes by cyclic voltammetry, and upon introduction of carbon monoxide (CO) gas, the Pt surface was fully passivated (prior to CO oxidation). However, the two individual responses of hydrazine and formic acid (HCOOH) are to be additive when combined in solution. No detrimental effects were observed upon the hydrazine voltammetry, even in the presence of excess formic acid, despite formic acid clearly displaying characteristic self-poisoning tendencies (primarily due to the formation of CO) in its own voltammetry. Effects intermediate to those of CO and formic acid were observed when methanol was present. Currents were essentially additive at low methanol content, but hydrazine oxidation current decreased by about 40% when an 100-fold excess of methanol was present, corresponding to poisoning by methanol dehydrogenation intermediates. These results are discussed with relevance to mixed fuels for more flexible or powerful fuel cells, and the possible formation of a random microelectrode array (templated by strongly adsorbed poison) on the microelectrode surface.

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“…18,19,21 Furthermore, a few studies on formate oxidation in alkaline solution have demonstrated that the oxidation current is extremely low even in the double layer potential region, where the surface is not poisoned by other adsorbates such as OH ad and anions. [37][38][39][40][41] However, in recent studies on formic acid oxidation at Pt electrodes using either conventional electrochemical or EC-ATR-FTIRS techniques, three research groups have concluded that bridge-bonded formate is the reactive intermediate in the direct pathway, which is responsible for the majority of the current for formic acid oxidation. However, they have proposed three distinct mechanisms for the formate pathway with either first or second order reaction kinetics.…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of the direct pathway for formic acid oxidation at a Pt(111) electrode

Yuan

Yang

et al. 2013

Phys. Chem. Chem. Phys.

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In order determine whether formate is a reaction intermediate of the direct pathway for formic acid oxidation at a Pt electrode, formic acid (HCOOH) oxidation at a Pt(111) electrode has been studied by normal and fast scan voltammetry in 0.1 M HClO4 solutions with different HCOOH concentrations. The relationship between the HCOOH oxidation current density (j(ox)) and formate coverage (θ(formate)) is quantitatively analyzed. The kinetic simulation reveals that the previously proposed formate pathway, with decomposition of the bridge-bonded formate (HCOO(B)) as a rate determining step (rds), cannot be the main pathway responsible for the majority of the current for HCOOH oxidation. Instead, a kinetic model based on a mechanism with formic acid adsorption [structure: see text], along with simultaneous C-H bond activation as the rds for the direct pathway, explains the measured data well. It was found for the relatively slow rate of formic acid oxidation, that adsorption-desorption of the formate is faster, which competes for the surface sites for formic acid oxidation.

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A switch effect in the oxidation behaviour of formate on Pt in alkaline solution caused by a differential pH change

Cited by 7 publications

References 14 publications

Influence of Solution pH on Pt Anode Catalyst in Direct Formic Acid Fuel Cells

Influence of Solution pH on Pt Anode Catalyst in Direct Formic Acid Fuel Cells

Towards Mixed Fuels: The Electrochemistry of Hydrazine in the Presence of Methanol and Formic Acid

On the mechanism of the direct pathway for formic acid oxidation at a Pt(111) electrode

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