Surface structures at the initial stages in passive film formation on Ni(1 1 1) electrodes in acidic electrolytes |
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Authors: | Masashi Nakamura Norihito Ikemiya Atushi Iwasaki Yasushi Suzuki Masatoki Ito |
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Institution: | Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan |
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Abstract: | The adsorption of sulfate or OH species and subsequent Ni(OH)2 film growth on Ni(1 1 1) single crystal electrodes has been investigated using in situ infrared reflection absorption spectroscopy (IRAS) as well as scanning tunneling microscopy (STM). In a pH 3 sulfuric acid solution, STM images show that a well-defined Ni(1 1 1) surface with a (1 × 1) lattice is exposed at ?300 mV, while hexagonal close-packed images with an atomic spacing of 0.32 nm are grown on this electrode at 300 mV. On the other hand, IRAS results in a sulfuric acid solution (pH 3) reveal that an absorption band at 1116 cm?1, which can be ascribed to ν(S–O) symmetric stretching of sulfate anion on Ni(1 1 1) surface, starts to appear at ?400 mV and develops its intensity with an electrode potential increase, while an absorption band at 930 cm?1 begins to develop at 0 mV on Ni(1 1 1), Ni(1 0 0) and Ni(1 1 0) electrodes, which can be assigned to an in-plane δ(Ni–OH) bending vibration in Ni(OH)2 passive film. |
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Keywords: | Infrared spectroscopy Ni electrode Thin film passivation |
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