Electrocatalytic Oxidation of Formate and Formic Acid on Platinum and Gold: Study of pH Dependence with Phosphate Buffers

Abdelrahman, Areeg; Hermann, Johannes M.; Kibler, Ludwig A.

doi:10.1007/s12678-017-0380-z

Cited by 17 publications

(36 citation statements)

References 39 publications

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“…For Pt electrodes, the reaction rates for the intermediate pathway on Pt(111) are negligible, because a sufficiently high formate coverage happens only at potentials too positive for the step leading to the formation of CO through reduction of the monodentate adsorbed formate to be fast, whereas on Pt(100) there is a potential window where this reaction is possible at higher formate coverage. Evidence that oxidation of formic acid also proceeds through adsorbed monodentate formate on other metal surfaces has been provided in the case of Au [30][31][40][41] and Pd 42 electrodes, as well as for several metal surfaces at the solid-gas interface. [43][44][45][46][47][48] Cyclic voltammetry and DFT calculations suggested that the stabilization of monodentate adsorbed formate can take place by the presence of adatoms or other adsorbed species on the Pt surface, 21 and a similar effect has been proposed recently for Bi-modified Pd nanoparticles also supported by theoretical calculations.…”

Section: Discussionmentioning

confidence: 99%

Adsorbed Formate is the Last Common Intermediate in the Dual-Path Mechanism of the Electrooxidation of Formic Acid

et al. 2020

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We report a study using Pt(111) and Pt(100) electrodes of the role of adsorbed formate in both the direct and indirect pathways of the electrocatalytic oxidation of formic acid. Cyclic voltammetry at different concentrations of formic acid and different scan rates and pulsed voltammetry were used to obtain a deeper insight into the effect of formate coverage on the rate of the direct pathway. Pulsed voltammetry also provided information on the effect of the concentration of formic acid on the rate of the formation of adsorbed CO on Pt(100). At low to medium coverage, increasing formate coverage increases the rate of its direct oxidation, suggesting that decreasing the distance between neighboring bidentate-adsorbed formate favors its interconversion to and/or stabilizes monodentate formate (the reactive species). However, increasing the formate coverage beyond approximately 50% results in a decrease of the rate of the direct oxidation, probably because bidentate formate is too closely packed for its conversion to monodentate formate to be possible. Cyclic voltammetry at very high scan rates reveals the presence of an order–disorder phase transition within the bidentate formate adlayer on Pt(111) when the coverage approaches saturation. The dependence of the potential of the maximum rate of dehydration to adsorbed CO, and of the rate at the maximum, on the concentration of formic acid is in good agreement with predictions made for a mechanism, in which adsorbed CO is formed through the adsorption of formate followed by its reduction to adsorbed CO, thus confirming that monodentate-adsorbed formate is the last intermediate common to both the direct and indirect pathways.

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Section: Discussionmentioning

confidence: 99%

Adsorbed Formate is the Last Common Intermediate in the Dual-Path Mechanism of the Electrooxidation of Formic Acid

et al. 2020

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“…Previous studies on the oxidation of formic acid on well-defined Pd layers on Pt were performed in H 2 SO 4 , showing interference by (bi) sulfate, which can strongly adsorb on Pd surfaces [26]. Adsorbed anions change the activity of formic acid oxidation on noble-metal electrodes due to site blocking and competitive adsorption [16,23,27]. Here, the voltammetric profiles for the oxidation of formic acid on Pt(100) and Pd ML Pt(100) are recorded in 0.1 M HClO 4 containing 50 mM HCOOH, in which the effect of anion adsorption can be neglected.…”

Section: Resultsmentioning

confidence: 99%

“…In this paper, we investigate formic acid oxidation on an epitaxially grown Pd monolayer on Pt(100) single crystal with a rotating electrode and demonstrate, for the first time, that formic acid oxidation on Pd ML Pt(100) in perchlorate acid is a mass-transport-limited process in a wide potential window. Such Levich behavior in formic acid oxidation has not been reported before although several research groups have used Pt [20][21][22] and Au [23] rotating disk electrodes to investigate the contribution of mass transport effect. Hoshi et al [13] concluded that the oxidation of formic acid on Pd single crystal electrodes was not controlled by diffusion from performing experiments in the solution stirred at 400 rpm.…”

Section: Introductionmentioning

confidence: 89%

Mass-transport-limited oxidation of formic acid on a Pd ML Pt(100) electrode in perchloric acid

Chen

Koper

2017

Electrochemistry Communications

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In this communication, we study the electrocatalytic formic acid oxidation process on an epitaxially grown Pd monolayer on a Pt(100) single crystal in perchloric acid. The formic acid oxidation activity on this Pd ML Pt(100) electrode in perchloric acid is significantly enhanced compared to the same electrode in sulfuric acid and compared to unmodified Pt(100), with a low onset potential of around 0.14 V RHE . The absence of hysteresis between the positive and negative scan during formic acid oxidation indicates the remarkable resistance to CO poisoning of the Pd monolayer surface. Most importantly, we report, for the first time, a mass-transport-limited formic acid oxidation rate on the Pd ML Pt(100) rotating electrode in perchlorate acid, setting a catalytic benchmark for future electrocatalysts for formic acid oxidation.

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“…However, several researchers show a volcano-type behavior of the electrocatalytic activity with the pH. Optimum pH conditions are usually found at around FA pKa (i.e., 3.75) [46,55,58,60,99,100], although Haan et al did not reach the maximum electrocatalytic activity in the pH range 0-5 [101], and Ferre-Vilaplana et al obtained an optimum pH of 5.5 [81]. In any case, from the literature review, the convenience of operating at pH closer to neutral conditions rather than strongly acidic or basic conditions seems clear.…”

Section: Bimetallic and Trimetallic Pt-based Catalystsmentioning

confidence: 99%

Benchmarking Catalysts for Formic Acid/Formate Electrooxidation

et al. 2021

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Energy production and consumption without the use of fossil fuels are amongst the biggest challenges currently facing humankind and the scientific community. Huge efforts have been invested in creating technologies that enable closed carbon or carbon neutral fuel cycles, limiting CO2 emissions into the atmosphere. Formic acid/formate (FA) has attracted intense interest as a liquid fuel over the last half century, giving rise to a plethora of studies on catalysts for its efficient electrocatalytic oxidation for usage in fuel cells. However, new catalysts and catalytic systems are often difficult to compare because of the variability in conditions and catalyst parameters examined. In this review, we discuss the extensive literature on FA electrooxidation using platinum, palladium and non-platinum group metal-based catalysts, the conditions typically employed in formate electrooxidation and the main electrochemical parameters for the comparison of anodic electrocatalysts to be applied in a FA fuel cell. We focused on the electrocatalytic performance in terms of onset potential and peak current density obtained during cyclic voltammetry measurements and on catalyst stability. Moreover, we handpicked a list of the most relevant examples that can be used for benchmarking and referencing future developments in the field.

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Electrocatalytic Oxidation of Formate and Formic Acid on Platinum and Gold: Study of pH Dependence with Phosphate Buffers

Cited by 17 publications

References 39 publications

Adsorbed Formate is the Last Common Intermediate in the Dual-Path Mechanism of the Electrooxidation of Formic Acid

Adsorbed Formate is the Last Common Intermediate in the Dual-Path Mechanism of the Electrooxidation of Formic Acid

Mass-transport-limited oxidation of formic acid on a Pd ML Pt(100) electrode in perchloric acid

Benchmarking Catalysts for Formic Acid/Formate Electrooxidation

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