The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

John, Samuel St.; Atkinson, Robert W.; Roy, Asa Logan; Unocic, Raymond R.; Papandrew, Alexander B.; Zawodzinski, Thomas A.

doi:10.1149/2.1071603jes

Cited by 12 publications

(6 citation statements)

References 31 publications

(67 reference statements)

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“…However, the HOR in the presence of HCO 3 − /CO 3 2− (as part of the carbonate cycle) may proceed as given by Equations :

true 2 normalH_{2} + 2 CO_{3}^{2 -} \to 2 normalH_{2} normalO + 2 CO_{2} + 4 normale^{-}

true 2 normalH_{2} + 4 HCO_{3}^{-} \to 4 normalH_{2} normalO + 4 CO_{2} + 4 normale^{-}

…”

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

“…Similar to the case of the ORR, these oxidation reactions likely take place as a two‐stage reaction (evidence for this based on reported results is presented below), including the reverse of Equation (1) and/or Equation (2), followed by Equation (9) …”

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

“…In contrast, the anode overpotential (operated with pure H 2 ) was significantly affected by CO 2 fed to the cathode, especially at low current densities (Figure ). However, some RDE experiments in aqueous solutions showed that the intrinsic kinetics (exchange current density and Tafel slope) were not appreciably affected by the presence of carbonates . These results imply that 1) the anode reaction with carbonate is most likely a two‐stage process: first to decarbonate and release OH − , followed by OH − oxidation of H 2 ; and 2) HCO 3 − /CO 3 2− anions formed in the cathode accumulate in the anode during fuel cell operation, which causes a decrease in both the conductivity and activity of OH − that work in concert to increase the anode overpotential.…”

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

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The Effect of Ambient Carbon Dioxide on Anion‐Exchange Membrane Fuel Cells

2018

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Over the past 10 years, there has been a surge of interest in anion-exchange membrane fuel cells (AEMFCs) as a potentially lower cost alternative to proton-exchange membrane fuel cells (PEMFCs). Recent work has shown that AEMFCs achieve nearly identical performance to that of state-of-the-art PEMFCs; however, much of that data has been collected while feeding CO -free air or pure oxygen to the cathode. Usually, removing CO from the oxidant is done to avoid the detrimental effect of CO on AEMFC performance, through carbonation, whereby CO reacts with the OH anions to form HCO and CO . In spite of the crucial importance of this topic for the future development and commercialization of AEMFCs, unfortunately there have been very few investigations devoted to this phenomenon and its effects. Much of the data available is widely spread out and there currently does not exist a resource that researchers in the field, or those looking to enter the field, can use as a reference text that explains the complex influence of CO and HCO /CO on all aspects of AEMFC performance. The purpose of this Review is to summarize the experimental and theoretical work reported to date on the effect of ambient CO on AEMFCs. This systematic Review aims to create a single comprehensive account of what is known regarding how CO behaves in AEMFCs, to date, as well as identify the most important areas for future work in this field.

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“…However, the HOR in the presence of HCO 3 − /CO 3 2− (as part of the carbonate cycle) may proceed as given by Equations :

true 2 normalH_{2} + 2 CO_{3}^{2 -} \to 2 normalH_{2} normalO + 2 CO_{2} + 4 normale^{-}

true 2 normalH_{2} + 4 HCO_{3}^{-} \to 4 normalH_{2} normalO + 4 CO_{2} + 4 normale^{-}

…”

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

Section: Effect Of Co2 and Hco3−/co32− On Electrochemical Reactions Imentioning

confidence: 99%

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The Effect of Ambient Carbon Dioxide on Anion‐Exchange Membrane Fuel Cells

2018

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“…Pourbaix diagrams, can help to ascertain the CMP supporting products of the mixed reactions. 34 OCP variations of a given system originate from competitive changes in its cathodic and anodic activities. 35 For instance, an anodic shift of E oc can come from a selective decrease in the electrode's anodic activity, or from a preferential increase in the corresponding cathodic steps.…”

Section: Results Of Ocp Transients and Potentiodynamic Polarization F...mentioning

confidence: 99%

An Alkaline Slurry Design for Co-Cu CMP Systems Evaluated in the Tribo-Electrochemical Approach

Johnson

Wei

Roy

2018

ECS J. Solid State Sci. Technol.

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The sub-14 nm technology nodes of integrated circuits require metal components of ultrathin linewidths. The chemical mechanical planarization (CMP) protocols needed to process such structures are associated with several challenges, one of which is to design/screen slurry formulations required to address both the scaling and the nontraditional metal chemistries of these structures. Laboratory scale tribo-electrochemical techniques serve as a cost-effective yet comprehensive means to aid these tasks, and the present work focuses on further quantifying this approach with an alkaline slurry formulation designed to planarize Co diffusion barriers for Cu lines. The CMP strategy uses controlled corrosion in a (potentially abrasive-free) slurry of potassium acetate, hydrogen peroxide, and benzotriazole. The tribo-electrochemical experiments involve open circuit potential transients, current interruption, and potentiodynamic polarization. Material removal rates, normalized with respect to the polisher parameters are analyzed as specific wear rates to quantitatively probe the chemical aspects of CMP. The slurry functions necessary to control galvanic corrosion and CMP selectivity of Co are investigated. The necessity for incorporating tribo-control in these measurements is demonstrated by showing how the results obtained with stationary metal samples could result in misleading conclusions about the galvanic corrosion rates.

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“…Near the electrode surface, methanol depletion or a local pH change because of the consumption of hydroxide ions and production of (bi)carbonates can occur. The change of the pH influences the local environment of the reaction and thereby directly affects the reaction pathway and resulting species. , A higher pH accelerates the reaction kinetics so that a reduction of the pH is followed by a slower kinetic and reduced reaction rate of the electrochemical reaction. Simulations of Schröder and Krewer showed for alkaline zinc air cells that the carbonation of the alkaline electrolyte rapidly consumes hydroxides, and thus prevents any long-term stable operation .…”

Section: Introductionmentioning

confidence: 99%

Origin of the Drastic Current Decay during Potentiostatic Alkaline Methanol Oxidation

Haisch

Kubannek

Chen

et al. 2020

ACS Appl. Mater. Interfaces

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The current production from the alkaline methanol electro-oxidation reaction does not reach a steady state on a smooth platinum catalyst under potentiostatic conditions. We investigated two possible explanations for this phenomenon: changes on the catalyst surface and changes in the solution near the electrode. In situ Fourier transform infrared spectroscopy experiments were conducted to evaluate the adsorbed species on the catalyst surface and a simulation model was set up to describe the changes of concentrations inside the solution. Linear-and bridge-bonded carbon monoxide are the only organic compounds which can be detected by in situ spectroscopy at fixed potentials, but their amount does not increase over time. The simulation shows that the consumption of hydroxide ions and production of carbonaceous species during alkaline oxidation causes a local pH shift near the catalyst surface. Assuming a one-electron transfer as the limiting step, this pH shift was found to contribute to the observed current loss at a potential of 0.77 V.

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The Effect of Carbonate and pH on Hydrogen Oxidation and Oxygen Reduction on Pt-Based Electrocatalysts in Alkaline Media

Cited by 12 publications

References 31 publications

The Effect of Ambient Carbon Dioxide on Anion‐Exchange Membrane Fuel Cells

The Effect of Ambient Carbon Dioxide on Anion‐Exchange Membrane Fuel Cells

An Alkaline Slurry Design for Co-Cu CMP Systems Evaluated in the Tribo-Electrochemical Approach

Origin of the Drastic Current Decay during Potentiostatic Alkaline Methanol Oxidation

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