Electrooxidation of methanol was studied on iridium in H2SG4 and HC104 solutions in connection with catalytic activities of the electrode in various oxidation states and of the adsorbed CO observed by infrared spectrometry. Iridium was found to show higher catalytic activity than platinum at low positive potential regions. The catalytic activity of iridium decreased with time at a constant-potential polarization and was inhibited by the introduction of CO gas. In situ infrared spectra were observed in the measurement conditions of electrode potential modulation and of constant electrode potential. The spectra for the above different conditions agreed in the wavenumber region of the spectra but not in absorbance intensity or in its relative values at different electrode potentials. The spectral maxima of the adsorbed CO, derived from methanol, were 2045 cm"1 at 0.2 V (vs. RHE) and 2054 cm"1 at 0.5 V. These maxima were shifted 20 cm"1 to higher wavenumber by the addition of CO gas. The catalytic activity of iridium was discussed in relation to redox coupling of iridium species in different oxidation states, the rate of their redox coupling, and the adsorbed CO observed by infrared spectroscopy.

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Novel ferroelectricity in 11-VI semiconducting ZnO was studied. The mechanism of ferroelectricity was examined based on size-mismatch model and electronic model. If the ionic size-mismatch between substituted and the host ions is important, the introduction of BeZf (ionic radius 0.3 A) may be more effective rather than Li' (0.60 A). On the other hand, if the changes in electronic configuration are important, the MgZL may play a different role from the isoelectronic Li' and Be". Dielectric measurements indicate that the introduction of Mg" instead of Li' suppresses T,, while isoelectronic Be" shows almost the same T,. This suggests that ZnO is the first ferroelectric with electronic origin.