کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
221014 463366 2007 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Oxidation of hydrogen on oxidized platinum : Part I: The tunneling current
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Oxidation of hydrogen on oxidized platinum : Part I: The tunneling current
چکیده انگلیسی

The hydrogen oxidation reaction (HOR) on bare and oxidized platinum in alkaline solution was studied at temperatures from 22 °C to 220 °C. It is found that the oxide film formed on platinum has a profound impact on the HOR rate, with the oxidation current decreasing exponentially with increasing overpotential. This inverse Tafel relationship can be explained by combining quantum mechanical tunneling theory with the point defect model (PDM) for film growth and dissolution. The tunneling constant, which is determined by the potential barrier height across the film/solution interface, is found to be temperature independent, if the anodizing constant is assumed to be invariant with temperature, and to be independent of pH and H2 concentration within the ranges of these independent variables studied. A barrier height of 0.31 eV is obtained from the derived tunneling constant. Based on the combined film growth-quantum mechanical tunneling theory, the HOR is employed as an in situ probe for characterizing the thin oxide film that forms on platinum in alkaline solution as a function of temperature. The calculated film thickness increases linearly with overpotential until the hydrogen oxidation current is too small to be differentiated from the total measured current, which comprises the passive current and the capacitive charging current when measured under potentiodynamic conditions. Compared with conventional techniques, this method has the advantage of being sensitive, convenient, and of an in situ character, although, at the current stage of development, it is limited to a maximum film thickness of 1–2 nm.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Electroanalytical Chemistry - Volume 600, Issue 1, 1 February 2007, Pages 205–216
نویسندگان
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