Platinum is deposited into porous carbon materials relevant for fuel cell electrodes using plasma sputtering techniques. The resulting platinum concentration profile extends up to 2 µm into the porous carbon and is well fitted by a generalized stretched Gaussian function, which displays the non thermal nature of the penetration process. Platinum deposits are observed to grow as clusters. On the outermost carbon particles, platinum nano-cluster sizes of 3.5 nm have been measured. In tests using actual PEM fuel cells, current densities as high as 1000 mA.cm −2 have been obtained at 400 mV with 25 cm 2 plasma electrodes. This compares favourably with commercially available electrodes but the present electrodes have a platinum density 4.5 times lower and hence can be considered to be significantly more efficient.

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A protection system for the JET ITER-like wall based on imaging diagnosticsa) Rev. Sci. Instrum. 83, 10D727 (2012); 10.1063/1.4738742Disentangling fluxes of energy and matter in plasma-surface interactions: Effect of process parametersThe knowledge of the effective energy deposited onto a surface by the reactive particles ͑ions, electrons, metastables, photons, etc.͒ in plasma processes such as thin-film deposition, sputtering, etching, etc., is of high interest to understand the basic mechanisms of energy transfer. In this article, a diagnostic is developed to directly measure the global energy transferred to surfaces ͑reactor walls, substrates, material to be modified, etc.͒ immerged in low-pressure plasmas. The diagnostic is based on a commercial HFM7-Vattel® microsensor, confined in a temperature-controlled substrate holder. The manufacturer calibration specifications are only given for atmospheric pressure. They cannot be used in low-pressure plasma conditions ͑typically 0.1-20 Pa͒. Thus, for this particular application, a calibration of the microsensor is required. It is performed at various pressures, between vacuum and the ambient, according to the NIST protocol and using a homemade blackbody ͑BB͒. It is shown that only curves obtained in vacuum or pressures below 0.1 Pa are valuable for a true calibration of the sensor. The others are perturbed by the heating of the gas in the BB surroundings. Measurements carried out in a typical transformer coupled plasma reactor in argon gas are presented. Typically the values are of the order of tens or hundreds of mW/ cm 2 in our experimental conditions. They are consistent with an estimation of the energy transferred by charged particles ͑ions and electrons͒ performed from Langmuir probe characterization of the plasma.

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