Abstract: A method and a device are provided for measuring a zeta potential with reproducibility, high reliability and high accuracy, by predicting an equilibrium value from the change over time of a streaming potential. In measurement of the zeta potential of a sample surface using a streaming potential method, an external pressure is changed in a step-wise manner, and a pressure change profile is set having a rising part or a falling part which is of a shorter time than the relaxation time T required for response to a change in the streaming potential accompanying the change in external pressure, and a steady part in which pressure is held at a steady state for a time longer than the relaxation time T. An asymptotic value of the streaming potential extrapolated from the transient response of the streaming potential occurring from the pressure change profile is used to calculate the zeta potential.

Abstract: Provided is a semiconductor photoelectrode comprising a conductive substrate; a first semiconductor photocatalyst layer provided on a surface of the conductive substrate; a second semiconductor photocatalyst layer provided on a surface of the first semiconductor photocatalyst layer. The semiconductor photoelectrode has a plurality of pillar protrusions on the surface thereof. A surface of each of the pillar protrusions is formed of the second semiconductor photocatalyst layer.

Abstract: A method for the production of a gas diffusion electrode having particles of a platinum group metal deposited on a carbon sheet is disclosed. This method comprises placing a water-repelling carbon sheet into contact with ozone, thereby oxidizing the surface of the sheet and forming a functional group on the surface, then immersing the sheet in a solution containing platinum group metal complex cations as dissolved seeds, thereby inducing ion exchange between the hydrogen ions present in the functional group and the platinum group metal complex cations and deposition of the platinum group metal complex cations on the carbon sheet, and further reducing the platinum group metal complex cations on the carbon into platinum group metal particles.