Quantitative investigation using X-ray photoelectron spectroscopy of oxidation of platinum catalyst films deposited by sputtering and spraying for fuel cell applications

摘要

The morphology and chemical composition of platinum coatings deposited by magnetron-ion sputtering of a platinum target in various modes (stationary, pulsed), and air spraying of platinum black on titanium supporting foils were studied. Metallic platinum subjected to ionic purification was used as a reference sample. It is shown that the composition of coatings in addition to platinum includes its oxides PtO (10-11 at %) and PtO2 (2-5 at %). The presence of oxides in the composition of platinum coatings is explained by the high specific surface of platinum in the coating, whereby partial oxidation takes place in the air. It has been found that the mode of magnetron-ion sputtering, as well as the presence of the Nafion (R) ionomer (5 wt %) in the air-spraying composition based on platinum black does not affect the phase composition of the coating. Morphological properties of the platinum coatings are influenced by the state of initial platinum source, and by the energy of the sputtered particles.