Measurement of the surface charge density of CO-saturated Pt(1 1 1) electrodes as a function of potential: the potential of zero charge of Pt(1 1 1)

From measurements of the charge flowing upon immersion, at controlled potential, of a CO-covered Pt(1 1 1) electrode in a 0.1 M HClO4 solution, the corresponding surface charge density vs. potential curve was obtained, and from this the potential of zero charge (pzc) of the CO-covered Pt(1 1 1) electrode. From these data it was estimated that the error incurred when the potential of zero total charge (pztc) of Pt(1 1 1) electrodes is determined by the CO-charge displacement method is of approximately 50 mV at pH 1 and of approximately 90 mV at pH 3. Furthermore, the experimentally determined pzc of the CO-covered Pt(1 1 1) electrode has allowed us to make an estimation of the potential of zero free charge (pzfc) of Pt(1 1 1) electrodes.