Electrochemical reactions can combine with efficient biochemical reactions, as in enzymatic catalytic reactions. In the case of man-made bio-catalytic (enzymatic) electrochemical reaction systems, there are two interfaces on an electrode; a solution phase-enzyme layer interface and an enzyme layer-electrode interface. These interfaces act as a chemical reaction interface and a physicochemical reaction interface respectively. In order to prepare efficient biomolecular electrochemical devices, the molecular interfaces have to be designed as optimized physical and chemical structure. The author has studied the functional and physical structures of macromolecular interfaces in bioelectronics properties and others. The present review describes the fabrication of molecular interfaces on an electrode, using functional protein molecules in order to obtain specific bioelectronic properties.

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The sintering behavior of (Sr_0.9La_0.1)_1−xTi_1−yO_3+δ powders (x, y=0, 0.04), synthesized using the citric acid method, has been investigated. Stoichiometric (Sr_0.9La_0.1)TiO_3+δ showed a single perovskite phase. For the non-stoichiometric samples, a Ruddlesden-Popper phase and TiO₂ phases were observed as secondary phases in the X-ray diffraction patterns of (Sr_0.9La_0.1)Ti_0.96O_3+δ and (Sr_0.9La_0.1)_0.96TiO_3+δ, respectively. It was found that during the sintering process, the samples expanded anomalously and then densified, although the powders showed good sinterability. The temperature at which the samples expanded was dependent on composition. Scanning electron microscopy observation of the samples showed that the volume expansion was caused by pore formation within the samples; however, no compositional changes were detected by X-ray diffraction during sintering.

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To investigate local phenomena of water flooding or drying up in a polymer electrolyte membrane fuel cell, a segmented cell consisting of perfectly insulated 5-cells was fabricated. The gas flow channels were designed to provide the reactant gases for a series of 5-cells in single direction without gas mixing or backflow under the operation. Through the I–V measurements of each cell varying oxygen utilization, dew point, gas pressure, and temperature gradients along gas flow, the local humidity conditions of each cell were analyzed. The local phenomena of water flooding or drying up and their influences on the overall cell performance can be understood well by introducing the H₂O vapor transportation index.

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In order to find a new type of oxide ion conductor, the electrical conduction was measured in the substituted perovskite-type oxides. In the present case, LaYO₃ was used as a based material with an orthorhombic and comparatively large unit cell, and a novel substitution method was introduced to intend to increase the concentration of oxide ions, e.g., LaY_1−xZr_xO_3+x/2. As a result, the LaYO₃-based perovskite-type solid solution was found to be formed, where the enhanced oxide ion conduction was observed as compared with that of the based material. A typical sample was LaY_0.95Zr_0.05O_3.025, the ionic conduction of which was 1.2×10⁻² S cm⁻¹ at 1000°C. Another substitution method of La_1−xZr_xYO_3+x/2 resulted in the analogous result. Considering these results and the further structural and density measurements, the charge carriers in these phases were expected to be due to interstitial oxide ions.

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