In situ FTIR study of pyridine adsorbed on Au(111),Au(100) and Au(110) electrodes

摘要

Pyridine-ds adsorbed on Au(111), Au(100), and Au(110) electrodes in 0.1 M NaF solution containing pyridine-ds (2 mM) have been investigated by in situ IRAS. For the three electrodes, an in-plane ring symmetrical vibration due to vertically adsorbed pyridine was observed around 1558 cm -1, which was accompanied by a decrease in the in-plane ring asymmetrical vibration at 1309 cm- 1 due to dissolved pyridine. For the low index electrodes, the behavior of the 1309 cm- 1 band intensities corresponding to the total amount of adsorbed pyridine agreed with the previous surface excess results obtained using chronocoulometry. The behavior of the 1558 cm- I band intensity for Au(lll) and Au( 100) was the same as that of the 1309 cm-1 band, indicating that the N-bonded pyridine was present at all of the adsorption potentials. For Au(lll) and Au( I 00), a new band appeared at 1550 cm- I for positive potentials, which was assigned to an in-plane ring symmetrical vibration, as in the 1558 cm- 1 case. We propose that the new band is due to the formation of an ordered domain of. the N-bonded pyridine. For the Au( 110) electrode, the adsorption behavior agreed with the previous surface excess results obtained using chronocoulometry.