Ryoichi Aogaki

Electrochemical instability of Ag/Sb co-deposition coupled with a magnetohydrodynamic flow

Abstract During electrodeposition of silver–antimony alloy, long-range spatial patterns appear spontaneously on a copper electrode surface. The patterns consist of small spiral waves and relatively large bands. It has been observed that the composition of the electrolyte solution varies the size of the spiral waves and that the propagation direction of the band changes under a strong magnetic field. These findings suggest that this pattern formation is sustained by flow-induced electrochemical instability. The origin of this instability is discussed in relation to the large overpotential in formation of the antimony clusters.

Analysis of gas dissociation rate into liquid phase under magnetic field gradient

The promotion of the dissolution rate of a gas into a liquid phase by a magnetic field gradient was theoretically examined. The Navier–Stokes equation was solved for the case when the magnetic force is induced by the concentration difference of the dissolved gas. As a result, the total diffusional flux was predicted to be proportional to the power of one-fourth the intensity of the magnetic field. An experimental confirmation for the theoretical equation of the dissolution process of oxygen into water was also performed.

MHD and Micro-MHD Effects in Electrochemical Systems

Using a new type of electrode, MHDE, copper electrodeposition from acidic copper sulfate solution was examined.

Electrochemical Detection of Magnetic Convection: Effect of High Magnetic Fields on O2/O2− Electrode Reaction in Acetonitrile

The electrode reaction of O2/O2− in acetonitrile was carried out in the bore of a superconducting magnet. The reduction current peak of molecular oxygen decreased with increasing intensity of magnetic flux densities beyond 5 T, and sigmoidal current potential curves as seen in steady-state voltammetries appeared on vertical orientation of working electrodes with respect to the magnetic field. This phenomenon shows the existence of a magnetic convection of oxygen molecule in the magnetic fields as alternative evidence.