Imaging of highly oriented pyrolytic graphite corrosion accelerated by Pt particles

Siroma, Zyun; Ishii, Kenta; Yasuda, Kazuaki; Miyazaki, Yoshinori; Inaba, Masaaki; Tasaka, Akimasa

doi:10.1016/j.elecom.2005.08.014

Cited by 91 publications

(64 citation statements)

References 6 publications

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“…Corrosion experiments carried out on graphite and amorphous C indicate that oxidation of amorphous C surfaces results in an increase in pore surface area [38]. The damage noted in these images is similar to that reported by [39]. Formation of cracks in the C matrix could be due to the evolution of gas (probably CO2), especially as they occur in regions where there is a high concentration high in Fe and O [40].…”

Section: Electrochemical Properties Of Biochar As Measured Using Solisupporting

confidence: 69%

The Electrochemical Properties of Biochars and How They Affect Soil Redox Properties and Processes

et al. 2015

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Biochars are complex heterogeneous materials that consist of mineral phases, amorphous C, graphitic C, and labile organic molecules, many of which can be either electron donors or acceptors when placed in soil. Biochar is a reductant, but its electrical OPEN ACCESSAgronomy 2015, 5 323 and electrochemical properties are a function of both the temperature of production and the concentration and composition of the various redox active mineral and organic phases present. When biochars are added to soils, they interact with plant roots and root hairs, micro-organisms, soil organic matter, proteins and the nutrient-rich water to form complex organo-mineral-biochar complexes Redox reactions can play an important role in the development of these complexes, and can also result in significant changes in the original C matrix. This paper reviews the redox processes that take place in soil and how they may be affected by the addition of biochar. It reviews the available literature on the redox properties of different biochars. It also reviews how biochar redox properties have been measured and presents new methods and data for determining redox properties of fresh biochars and for biochar/soil systems.

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Section: Electrochemical Properties Of Biochar As Measured Using Solisupporting

confidence: 69%

The Electrochemical Properties of Biochars and How They Affect Soil Redox Properties and Processes

et al. 2015

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“…The influence of Pt on the carbon corrosion became less pronounced at temperature higher than 50°C. By using the field emission-scanning electron microscopy (FE-SEM) to examine a highly oriented pyrolytic graphite (HOPG) electrode with the Pt nanoparticles on top, CO 2 formation is mostly found around the Pt particles, but interestingly these Pt particles are still present without becoming detached, despite carbon corrosion and blister formation [95]. In a recent paper Ball et al found no effect of Pt on the corrosion.…”

Section: Carbon Oxidationmentioning

confidence: 98%

“…In the initial operation period, the carbon corrosion can unblock these Pt particles and therefore increase the catalyst surface available for reaction. However, in the long run, the negative effects of carbon corrosion dominate through increased hydrophilicity of the oxidised carbon surface, reduced location sites and electronic contact for Pt particles and modified gas permeability of the gas diffusion layer [95].…”

Section: Reviewmentioning

confidence: 99%

Review: Durability and Degradation Issues of PEM Fuel Cell Components

2008

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Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75 °C, using optimal stack and flow design, the voltage degradation can be as low as 1–2 μV·h. However, the degradation rates can increase by orders of magnitude when conditions include some of the following, i.e. load cycling, start–stop cycles, low humidification or humidification cycling, temperatures of 90 °C or higher and fuel starvation. This review paper aims at assessing the degradation mechanisms of membranes, electrodes, bipolar plates and seals. By collecting long‐term experiments as well, the relative importance of these degradation mechanisms and the operating conditions become apparent.

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“…It has been shown in [17,28,29] that the presence of platinum accelerates the corrosion of the carbon support, and that the corrosion rate depends on the platinum loading. The onset potential at which carbon is oxidised to CO 2 , as measured by mass spectroscopy, reduced from 1.1 to 0.55 V versus RHE when the platinum loading increased from 0 to 39%.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Potentiostatic Stability of PEMFC Electro Catalysts at Elevated Temperatures

2009

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The electrochemical stability of platinum on carbon catalyst (Hispec™ 4000, Johnson Matthey) has been investigated predominantly at constant potentials ranging from 0.95 to 1.25 V at elevated temperatures. By combining a quartz crystal microbalance (QCM) with electrochemical techniques, dynamic insight is obtained on the oxidation and corrosion of both platinum and carbon during potentiostatic hold. From the cyclic voltammetry (CV) data, it can be concluded that at all conditions, the platinum surface area decreases when Pt on carbon catalysts are exposed to a constant potential of 1.05 to 1.25 V. Under the applied conditions, this loss of surface area is primarily caused by the dissolution of platinum.Both the QCM as well as on‐line electrochemical mass spectrometry (OLEMS) experiments show that the corrosion of carbon is catalysed by the presence of platinum at 80 °C, as long as the platinum surface is not passivated by an oxide layer.

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Imaging of highly oriented pyrolytic graphite corrosion accelerated by Pt particles

Cited by 91 publications

References 6 publications

The Electrochemical Properties of Biochars and How They Affect Soil Redox Properties and Processes

The Electrochemical Properties of Biochars and How They Affect Soil Redox Properties and Processes

Review: Durability and Degradation Issues of PEM Fuel Cell Components

Determination of the Potentiostatic Stability of PEMFC Electro Catalysts at Elevated Temperatures

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