Oxygen-Enhanced Dissolution of Platinum in Acidic Electrochemical Environments

Matsumoto, Masashi; Miyazaki, Takashi; Imai, Hideto

doi:10.1021/jp201959h

Cited by 100 publications

(145 citation statements)

References 32 publications

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“…Therefore, the ECSA was normalized by the cycle number, shown in Figure 3b, and resulted in greater platinum loss per cycle for longer dwell times. This is consistent with accepted understanding; Matsumoto et al 12 conducted analysis of both cycling and potential hold ASTs and showed a greater Pt dissolution rate with cycling, and an even greater dissolution rate by cycling in the presence of O 2 compared to N 2 . The authors proposed that in the presence of O 2 there was a greater place exchange of oxygen into the Pt crystal resulting in high-order Pt oxide formation.…”

supporting

confidence: 88%

“…Figure 3a shows the ECSA plotted against the total accumulated UPL time, which initially gives the impression that greater dwell times lead to less ECSA loss. Since the number of cycles is a known stressor for platinum dissolution 12 the lower ECSA loss at longer dwell times was associated with fewer AST cycles. Therefore, the ECSA was normalized by the cycle number, shown in Figure 3b, and resulted in greater platinum loss per cycle for longer dwell times.…”

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confidence: 99%

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A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

Young

Colbow

Harvey

et al. 2013

J. Electrochem. Soc.

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The cathode CL of a polymer electrolyte membrane fuel cell (PEMFC) was exposed to high potentials, 1.0 to 1.4 V versus a reversible hydrogen electrode (RHE), that are typically encountered during start up/shut down operation. While both platinum dissolution and carbon corrosion occurred, the carbon corrosion effects were isolated and modeled. The presented model separates the carbon corrosion process into two reaction steps; (1) oxidation of the carbon surface to carbon-oxygen groups, and (2) further corrosion of the oxidized surface to carbon dioxide/monoxide. To oxidize and corrode the cathode catalyst carbon support, the CL was subjected to an accelerated stress test cycled the potential from 0.6 V RHE to an upper potential limit (UPL) ranging from 0.9 to 1.4 V RHE at varying dwell times. The reaction rate constants and specific capacitances of carbon and platinum were fitted by evaluating the double layer capacitance (Cdl) trends. Carbon surface oxidation increased the Cdl due to increased specific capacitance for carbon surfaces with carbon-oxygen groups, while the second corrosion reaction decreased the Cdl due to loss of the overall carbon surface area. The first oxidation step differed between carbon types, while both reaction rate constants were found to have a dependency on UPL, temperature, and gas relative humidity. Early polymer electrolyte membrane fuel cell (PEMFC) research used platinum black as the catalyst for both the cathode and anode electrodes. These electrodes were costly due to their very high Pt loadings (>>1.0 mg/cm 2 ). One of the ways of reducing the platinum loading was to replace platinum black with dispersed platinum nanoparticles on a carbon support. The smaller platinum particles on carbon enabled a reduced Pt loading of the cathode to less than 0.5 mg/cm 2 , while maintaining the required platinum surface area required for high fuel cell performance. Although cost was reduced, the durability of the fuel cell was negatively impacted. At potentials greater than 0.2 V RHE (reversible hydrogen electrode), the carbon support is thermodynamically unstable and able to oxidize to carbon dioxide (CO 2 ) and/or carbon monoxide (CO) [Eqs. 1-3], 1 leaving the platinum unsupported and inactive. Furthermore, due to the loss of support the platinum particles have been shown to agglomerate into larger particles, dissolve into the ionomer, or get washed out of the system.Even in the presence of platinum, the kinetics of carbon oxidation/corrosion is relatively slow; therefore, carbon is quite stable under normal PEMFC operating conditions. In practice, elevated cathode potentials of greater than 1.2 V RHE are required to oxidize carbon at reaction rates high enough to cause significant structural degradation. Normal PEMFC operation occurs between 0-1.0 V RHE ; however, upon fuel starvation or gas switching conditions (start-up and shutdown operation due to infiltration of oxygen into the normally hydrogen filled anode compartment during fuel cell off conditions) the cathode potential can exceed ...

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supporting

confidence: 88%

mentioning

confidence: 99%

A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

Young

Colbow

Harvey

et al. 2013

J. Electrochem. Soc.

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“…In addition to the unsatisfactory ORR activity, there are also problems associated with performance loss with long term operation due to aggregation and dissolution of Pt particles and carbon corrosion [2][3][4][5][6][7]. Consequently, the activity and durability of Pt/C catalysts must both be improved for wide-spread commercialization of polymer electrolyte fuel cells [1,8].…”

Section: Introductionmentioning

confidence: 99%

Improving oxygen reduction reaction activity and durability of 1.5nm Pt by addition of ruthenium oxide nanosheets

Takimoto

Chauvin

Sugimoto

2013

Electrochemistry Communications

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The durability of commercial carbon supported Pt nanoparticles with average particle size of 1.5 nm (20 mass% Pt/C) has been improved by the addition of ruthenium oxide nanosheets (RuO2ns) without sacrificing the initial activity towards oxygen reduction reaction.The initial oxygen reduction reaction activity of the composite catalyst was slightly higher than as-received Pt/C. The electrocatalytic activity after consecutive potential cycling tests of the composite catalyst was c.a. 1.3 times higher than non-modified Pt/C. The increased durability of the composite catalyst is attributed to the improved preservation of the electrochemically active Pt surface area with the addition of ruthenium oxide.

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“…Ref. [28]), the difference in the dissolution in oxygen-free and oxygen-saturated solutionsw as shown, which, however,w as not found for transient dissolution.…”

mentioning

confidence: 92%

“…[26][27][28][29][30][31][32] In these works, the onset of dissolution( sometimes specified as anodic dissolution) varies between approximately 0.6 and 1.0 V RHE ,w hich is significantly lower than that observed in the on-line ICP-MS studies when using similarb ulk electrodes. [6a, b, f, 12, 33] In some of these works (e.g.…”

mentioning

confidence: 99%

Dissolution of Platinum in the Operational Range of Fuel Cells

et al. 2015

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The front cover artwork is provided by the Electrocatalysis Group at the Max‐Planck‐Institut für Eisenforschung GmbH (Germany). The image shows, symbolically, the investigation of the dissolution of carbon‐supported platinum nanoparticles by using a scanning flow‐cell‐based setup with on‐line detection of dissolution products through ICP–MS. Read the full text of the Article at 10.1002/celc.201500098.

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Oxygen-Enhanced Dissolution of Platinum in Acidic Electrochemical Environments

Cited by 100 publications

References 32 publications

A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

A Semi-Empirical Two Step Carbon Corrosion Reaction Model in PEM Fuel Cells

Improving oxygen reduction reaction activity and durability of 1.5nm Pt by addition of ruthenium oxide nanosheets

Dissolution of Platinum in the Operational Range of Fuel Cells

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