Adsorption of phosphate species on poly-oriented Pt and Pt(1 1 1) electrodes over a wide range of pH

Gisbert, Rubén; Garcı́a, Gonzalo; Koper, Marc T. M.

doi:10.1016/j.electacta.2010.04.009

Cited by 114 publications

(128 citation statements)

References 26 publications

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“…The Rct for pH 7 is shown for comparison with the alkaline pH values (pH 7 was measured in a phosphate buffer, but since there is no phosphate adsorption in the H-UPD region 30 , we do not expect an impact of phosphate on the hydrogen adsorption rate). From the figure we observe that the charge transfer resistance is both pH-and potential-dependent.…”

Section: Resultsmentioning

confidence: 99%

Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

et al. 2017

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The hydrogen evolution on platinum is a milestone reaction in electrocatalysis as well as an important reaction towards sustainable energy storage. Remarkably, the pH dependent kinetics of this reaction is not yet fully understood. Here, we present a detailed kinetic study of the hydrogen adsorption and evolution reaction on Pt(111) in a wide pH range. Impedance and Tafel slope measurements show that the hydrogen adsorption and hydrogen evolution are both slow in alkaline media, which is consistent with the observation of a shift in the rate-determining step for H2 evolution.Adding nickel to the Pt(111) surface lowers the barrier for the hydrogen adsorption rate in alkaline solutions and thereby enhances the hydrogen evolution rate. These observations are explained by a new model which highlights the role of the reorganization of interfacial water to accommodate charge transfer through the electric double layer, the energetics of which is controlled by how strongly water interacts with the interfacial field. The new model is supported by laser-induced temperature-jump measurements. Our model sheds new light on the origin of the slow kinetics for the hydrogen evolution reaction in alkaline media.

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Section: Resultsmentioning

confidence: 99%

Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

et al. 2017

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“…The CO bands disappear at around 0.8 V due to the oxidative removal of CO ads and a new band emerges at 1325 cm -1 at around 0.5 V. This band has been assigned to the symmetric O-C-O stretching mode of bridge-bonded adsorbed formate [9], while the asymmetric O-C-O stretching mode of the bridge-bonded adsorbed formate, expected around 1590 cm -1 , is not observed in the spectra due to the surface selection rule in SEIRAS [43]. The broad band at ~ 1050 cm -1 that emerges after CO ads being oxidized A c c e p t e d M a n u s c r i p t [44]). The spectral changes are reversed during the subsequent negative-going scan.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the absence of bridge-bonded adsorbed formate in the neutral solution is not due to its rapid oxidation. The strong band around 1130 cm -1 in the spectra that appears after the oxidative removal of CO ads is assigned to a P-O stretching mode of a phosphate anion adsorbed on the electrode surface (HPO 4 − [44]). In the negative-going scan, a very weak band assigned to either carbonate [46] or bicarbonate [47] derived from CO 2 is observed around 1450 cm -1 .…”

Section: Seira Spectra and Cyclic Voltammogramsmentioning

confidence: 99%

The effect of pH on the electrocatalytic oxidation of formic acid/formate on platinum: A mechanistic study by surface-enhanced infrared spectroscopy coupled with cyclic voltammetry

Joo

Uchida

Cuesta

et al. 2014

Electrochimica Acta

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132

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Please cite this article as: J. Joo, T. Uchida, A. Cuesta, M.T.M. Koper, M. Osawa , The effect of pH on the electrocatalytic oxidation of formic acid/formate on platinum: A mechanistic study by surface-enhanced infrared spectroscopy coupled with cyclic voltammetry, Electrochimica Acta (2014), http://dx.doi.org/10. 1016/j.electacta.2014.02.040 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe electrocatalytic oxidation of formic acid (HCOOH) and formate (HCOO − ) to CO 2 on platinum has been studied over a wide range of pH (0-12) by surface-enhanced infrared absorption spectroscopy (SEIRAS) coupled with cyclic voltammetry. The peak current of HCOOH/HCOO − oxidation exhibits a volcano-shaped pH dependence peaked at a pH close to the pK a of HCOOH (3.75). The experimental result is reasonably explained by a simple kinetic model that HCOO − oxidation is the dominant reaction route over the whole pH range.HCOOH is oxidized after being converted to HCOO − via the acid-base equilibrium. The ascending part of the volcano plot at pH < 4 is ascribed mostly to the increase of the molar ratio of HCOO − , while the descending part at pH > 4 is ascribed to the suppression of HCOO − oxidation by adsorbed OH or oxidation of the electrode surface. In acidic media, HCOOH is

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“…Many studies have shown that the PA is a key factor for the observed lower current densities in HT-PEMFCs, while especially the oxygen reduction reaction (ORR) taking place on the cathode is severely affected by the PA electrolyte. The inhibiting effect of the electrolyte on the ORR activity has been often explained by strong adsorption of PA ions on active catalyst sites [5][6][7][8][9]. We have recently demonstrated using cyclic voltammetry that adding even trace amounts of PA to electrolyte solutions that weakly interact with Pt-catalyst surfaces can lower the ORR catalytic activity by more than one order of magnitude [10].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of temperature and electrolyte concentration dependent Oxygen solubility and diffusivity in phosphoric acid

Fleige

Holst-Olesen

Wiberg³

et al. 2016

Electrochimica Acta

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Reactant diffusion and solubility is of utmost important for providing sufficient reactant concentrations at a catalytic active surface. In high temperature proton exchange membrane fuel cells (HT-PEMFCs) the electrolyte consists of concentrated phosphoric acid embedded into a polybenzimidazole (PBI) membrane. Despite the elevated operation temperature of 150°C, the observed oxygen reduction reaction (ORR) rates in HT-PEMFCs are significantly lower than in low temperature PEMFCs. Reduced reactant transport in combination with site blocking is often mentioned as possible inhibition factors. As a step towards studying the ORR under realistic conditions in half-cell setups, in the present study we investigate the oxygen solubility and diffusivity in diluted phosphoric acid electrolyte in a temperature range of 5 to 80 °C. The presented 2 work demonstrates and discusses under which conditions reliable data for these constants can be obtained. In particular it is shown that the product of oxygen solubility and diffusivity, which determines the oxygen mass transport, first increases as function of temperature, but then decreases again above 60 °C. It seems that the decrease in oxygen solubility at higher temperatures is correlated to an increase in the apparent ORR activation energy.

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Adsorption of phosphate species on poly-oriented Pt and Pt(1 1 1) electrodes over a wide range of pH

Cited by 114 publications

References 26 publications

Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

The effect of pH on the electrocatalytic oxidation of formic acid/formate on platinum: A mechanistic study by surface-enhanced infrared spectroscopy coupled with cyclic voltammetry

Evaluation of temperature and electrolyte concentration dependent Oxygen solubility and diffusivity in phosphoric acid

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