Oxygen Reduction at Pt0.65Cr0.35, Pt0.2Cr0.8 and Roughened Platinum

Paffett, Mark T.; Beery, J. G.; Gottesfeld, S.

doi:10.1149/1.2096016

Cited by 281 publications

(155 citation statements)

References 6 publications

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“…However, when the testing conditions become more aggressive, a combination of higher temperatures and acid concentrations, the peak increases temporarily before starting to decrease. We attribute this behavior to a temporary increase in active surface area due to an increase in the roughening of the surface caused by the dissolution of the metal particles [10,11]. At higher temperatures and H 2 SO 4 concentrations the conditions are more aggressive and rapid dissolution of the metal particles produces steadily decreasing peformance.…”

Section: Cyclic Voltammetrymentioning

confidence: 92%

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Colón-Mercado

Hobbs

2007

Electrochemistry Communications

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Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process which uses a sulfur dioxide depolarized electrolyzer (SDE) to produce the hydrogen. Testing examined the activity and stability of platinum and palladium as the electrocatalyst for the SDE in sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by the concentration of the sulfuric acid electrolyte. INTRODUCTIONConcerns about the dependence on petroleum imports, poor air quality, and greenhouse emissions have accelerated the development of energy systems using hydrogen as an energy carrier. Hydrogen can be extracted using a variety of technologies, which can be divided in three main categories: thermal, electrochemical, and biological. Among the production methods water electrolysis is a well established technology, which is capable of producing emission free hydrogen if used in conjunction with renewable or nuclear energy [1]. However, the technology and energy inputs for the electrolysis process can make the production of hydrogen by this method expensive. In order to produce global scale quantities of hydrogen in a more energy efficient process, thermochemical water splitting cycles using heat from a nuclear reactor have been proposed and developed since the late 1960s [2].Among the many possible thermochemical cycles for the production of hydrogen, the sulfur-based cycles lead the competition in overall energy efficiency.A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process. The HyS cycle uses a sulfur dioxide-depolarized electrolyzer (SDE) to produce hydrogen. The electrolyzer oxidizes sulfur dioxide to form sulfuric acid at the anode [r1] and reduces protons to form hydrogen at the cathode [r2]. The overall electrochemical cell reaction consists of the production of H 2 SO 4 and H 2 [r3]. The key attribute of the reactions occurring in the SDE is the anodic reaction [r1], which occurs at a standard half cell potential of -0.158 V vs. standard hydrogen electrode (SHE) [3]. Compared with low temperature pure water electrolysis, which occurs at -1.23 V vs. SHE, the SDE could potentially produce the same amount of hydrogen with almost one eighth of the current used in conventional electrolysis.

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Section: Cyclic Voltammetrymentioning

confidence: 92%

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Colón-Mercado

Hobbs

2007

Electrochemistry Communications

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“…The use of platinum, however, causes high cost, and platinum resources are limited, thereby restraining the actual commercialization of PEFCs. Therefore, many researchers have improved the ORR activity and durability to reduce the usage of platinum by different methods such as alloying it with other transition metals, such as Fe, Ni, and Co, [1][2][3][4][5][6] and the formation of core-shell structures. [7][8][9][10] The drastic reduction in platium usage, however, would be difficult to achieve because the highly dispersed platinum alloys and coreshell particles generally become unstable and dissolve easily under cathode conditions, resulting in decreasing cell performance during long-term operation.…”

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confidence: 99%

Effect of Reheating Treatment on Oxygen-Reduction Activity and Stability of Zirconium Oxide-Based Electrocatalysts Prepared from Oxy-Zirconium Phthalocyanine for Polymer Electrolyte Fuel Cells

Okada

Ishihara

Matsumoto

et al. 2015

J. Electrochem. Soc.

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Zirconium oxide-based electrocatalysts with multi-walled carbon nanotubes as electroconductive support (ZrC x N y O z /MWCNT) were prepared by oxidation of oxy-zirconium phthalocyanine under low oxygen partial pressure and examined as new non-platinum cathodes for polymer electrolyte fuel cells. The effect of reheating treatment of ZrC x N y O z /MWCNT in the temperature range from 900 to 1200 • C for 1 h under nitrogen atmosphere on the activity and stability of the oxygen-reduction reaction (ORR) was investigated. The reheating treatment at 1000 • C enhanced the ORR activity because of the formation of oxygen vacancies, which might act as active sites for the ORR. The reheating treatment at temperatures above 1100 • C, however, led to the formation of carbonitrides which are unstable under cathode conditions, resulting in decrease in the ORR activity. The reheating treatment significantly increased the durability of ORR at both low (0.6 V vs. reversible hydrogen electrode (RHE)) and high (1.2 V) potential.The reheating treatment at higher temperatures promoted graphitization of the deposited carbon. Because the degradation in the high-potential region mainly originates from corrosion of the carbon materials, graphitization would be effective to improve the durability.

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“…Cell performance was highest for the lowest Pt loaded alloys with a gain of 120 mV at 200 mA/mg Pt at 180 • C. This is not surprising considering the lower values of the Pt-Pt interatomic spacing and lattice parameters observed for those alloys. As discussed by Jalan and Taylor [111] and later corroborated by Kim et al [112] (who utilized their own acid leaching process as well as potential excursion techniques outlined by Gottesfeld and associates [113,114] to roughen the alloy catalyst surface) and Min et al [107], lower interatomic spacing generally trends towards higher specific activity (see Figure 1).…”

Section: Orr Catalyst Activity In Free Electrolyte: Alternative Catalystmentioning

confidence: 71%

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

2017

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High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are being studied due to a number of benefits offered versus their low temperature counterparts, including co-generation of heat and power, high tolerance to fuel impurities, and simpler system design. Approximately 90% of the literature on HT-PEM is related to the electrolyte and, for the most part, these electrolytes all use free phosphoric acid, or similar free acid, as the ion conductor. A major issue with using phosphoric acid based electrolytes is the free acid in the electrodes. The presence of the acid on the catalyst sites leads to poor oxygen activity, low solubility/diffusion, and can block electrochemical sites through phosphate adsorption. This review will focus on these issues and the steps that have been taken to alleviate these obstacles. The intention is this review may then serve as a tool for finding a solution path in the community.

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Oxygen Reduction at Pt0.65Cr0.35, Pt0.2Cr0.8 and Roughened Platinum

Cited by 281 publications

References 6 publications

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Effect of Reheating Treatment on Oxygen-Reduction Activity and Stability of Zirconium Oxide-Based Electrocatalysts Prepared from Oxy-Zirconium Phthalocyanine for Polymer Electrolyte Fuel Cells

Catalyst, Membrane, Free Electrolyte Challenges, and Pathways to Resolutions in High Temperature Polymer Electrolyte Membrane Fuel Cells

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