Shin-ya Kishioka

FTO/SnO2/BiVO4 Composite Photoelectrode for Water Oxidation under Visible Light Irradiation

An SnO 2 layer prepared from ethanol solution was applied to fabricate an MO/SnO 2 /BiV0 4 composite photoelectrode. The layered composite films were characterized by X-ray diffraction, scanning electron microscope, and X-ray photoelectron spectroscopy techniques. The photocurrent efficiency of BiVO 4 increased remarkably when an SnO 2 film was layered between the BiVO 4 layer and the fluorine-doped tin oxide (FTO) conducting electrode, indicating the efficient charge separation via the electron transfer from BiVO 4 to SnO 2 and the blocking of the hole transfer from BiVO 4 to the FTO surface. It was also demonstrated that the sequence for depositing the individual metal oxide layer on the FTO substrate was an important factor for such efficient charge separation of the electrode.

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.

A Novel Proton Conductor Based on Ternary Polymer Blend

A novel proton conductor based on a ternary polymer blend has been studied and compared with that based on binary systems. Binary and ternary polymer films were prepared using recast solutions containing poly(acrylic acid), poly(vinyl butyral) and vinylidene-fluoride-based copolymer. The relationship between polymer composition and ac conductivity has been investigated. As a result, it has been proven that the ternary system containing 50 wt% poly(acrylic acid), 20 wt% poly(vinyl butyral) and 30 wt% vinylidene-fluoride-based copolymer exhibits a higher conductivity than Nafion. The ternary polymer film has shown considerable stability under H2O saturated N2 gas at 98°C.