The adsorption and oxidation of hydrogen on Pt film has been studied by means of in situ real-time attenuated total reflection infrared spectroscopy. Strong hydrogen signal was obtained, which is usually very weak or hard to be detected. By applying the curve-fitting analysis to the spectra, it is concluded that three different terminal hydrogen species, which correspond to the peaks at 1893, 1988, and 2070 cm–1, formed during the adsorption of hydrogen. In H2 flow, the peak at 2070 cm–1 reached the highest intensity quickly and then gradually decreased, which may be due to the surface restructuring of surface sites induced by hydrogen. Water and hydride, which correspond to the peaks at 1631 and 2116 cm–1, respectively, formed after the Pt film was exposed to H2 and then O2. However, hydrogen species cannot be fully oxidized in O2, which may be because some hydrogen species are beneath the Pt surface and cannot be reached by oxygen. It was deduced that hydride was formed by the interaction between adsorbed hydrogen and positively charged Pt sites induced by oxygen. The amounts of hydrogen species and hydride decreased gradually in the mixture of H2 and O2, which may be due to the increased coverage of water and the hydrolysis of hydride in the presence of water. The hydrogen adsorption and oxidation mechanism on Pt may shed light on the catalytic reactions involving hydrogen as well as hydrogen storage on metals.
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Dong et al. (2013) studied this question.
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