Masamori Iida

Bio: Masamori Iida is an academic researcher from Tokai University. The author has contributed to research in topics: Diamond & Chemical vapor deposition. The author has an hindex of 19, co-authored 82 publications receiving 1420 citations.

Formation Mechanism of p-Type Surface Conductive Layer on Deposited Diamond Films

Abstract: A model of the formation of a p-type surface conductive layer on deposited diamond films is proposed. According to the model, the ionization of acid in water produces oxonium ion ( H3O+) which reacts with hydrogen on diamond films and causes the creation of holes in diamond films. The model also explains the disappearance of the p-type surface conductive layer by the action of alkaline substances. The experimental results concerning the change in electrical resistance at the surface of diamond films can be explained using the proposed model.

Fabrication of a diamond field emitter array

Abstract: A diamond field emitter array has been fabricated. by Chemical vapor deposition. Diamond was grown on an inverted pyramidal‐shape Si substrate followed by removal of the substrate. The fabricated array was placed in a high vacuum pumping system with the pressure of ∼10−7 Torr and the emission current as a function of the anode voltage was measured. The distance between the tungsten anode and the diamond surface was held constant at 100 μm throughout the measurement. As a result, a current larger than 10−4 A was obtained for an anode voltage of 6 kV. A linear relationship in the Fowler–Nordheim plot indicated the existence of electron field emission from the fabricated diamond field emitter array.

Water electrolysis using diamond thin-film electrodes

Abstract: Thin, boron-doped diamond films formed on a silicon substrate were evaluated during water electrolysis in acidic solution in order to determine their potential for industrial use. Though the electrode exhibited overvoltages in excess of 2 V in the industrial current range, ozone gas was produced at a current efficiency of a few percent at ambient temperature. It was confirmed that the consumption rate of the highly doped sample was small and comparable with a platinum-plated anode, indicating that the diamond is dimensionally stable under extreme conditions. The failure mechanism in the test is discussed on the basis of scanning electron microscopy, X-ray diffraction, and Raman analyses. The spalling of the film from the substrate, which was observed in the deteriorated sample after the electrolysis, is attributed to the residual stress that accumulated during the production process carried out under high temperature.

Characterization of Boron-Doped Diamond Film

Abstract: Diamond films doped with boron were fabricated by the thermal filament CVD method. Powdered B2O3 was used as the doping source. The films were identified as diamond by means of several methods including Raman spectroscopy. The resistivity of the films was inversely proportional to the B/C ratio over four orders. The temperature dependence of current was measured and to fit this result to the theoretical calculation, the activation energy was evaluated.

Electrode for electrolysis and electrolytic cell using the electrode

Abstract: An electrode for electrolysis comprising an electrode base material and an electrode substance having an electrically conductive diamond structure covering the surface of the electrode base material. The electrode substance having an electrically conductive diamond structure may be a diamond containing an impurity selected from boron, phosphorus and graphite. Alternatively, the electrode substance having an electrically conductive diamond structure may comprise a composite of a diamond and an electrically conductive material. In a preferred embodiment, the electrode further comprises an interlayer comprising at least one of the carbide of a valve metal and silicon carbide disposed between the electrode base material and the electrode substance having an electrically conductive diamond structure. Also disclosed is an electrolytic cell having two chambers including an anode chamber and a cathode chamber partitioned by an ion-exchange membrane. At least one of the anode placed in the anode chamber and a cathode placed in the cathode chamber is an electrode comprising an electrode base material and an electrode substance having an electrically conductive diamond structure covering the surface of the electrode base material. An electrolytic cell having three chambers is also disclosed, including an anode chamber, an intermediate chamber and a cathode chamber partitioned by ion-exchange membranes. At least one of an anode placed in the anode chamber and a cathode placed in the cathode chamber is an electrode comprising an electrode base material and an electrode substance having an electrically conductive diamond structure covering the surface of the electrode base material.

Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review

Abstract: As the environment preservation gradually becomes a matter of major social concern and more strict legislation is being imposed on effluent discharge, more effective processes are required to deal with non-readily biodegradable and toxic pollutants. Synthetic organic dyes in industrial effluents cannot be destroyed in conventional wastewater treatment and consequently, an urgent challenge is the development of new environmentally benign technologies able to mineralize completely these non-biodegradable compounds. This review aims to increase the knowledge on the electrochemical methods used at lab and pilot plant scale to decontaminate synthetic and real effluents containing dyes, considering the period from 2009 to 2013, as an update of our previous review up to 2008. Fundamentals and main applications of electrochemical advanced oxidation processes and the other electrochemical approaches are described. Typical methods such as electrocoagulation, electrochemical reduction, electrochemical oxidation and indirect electro-oxidation with active chlorine species are discussed. Recent advances on electrocatalysis related to the nature of anode material to generate strong heterogeneous OH as mediated oxidant of dyes in electrochemical oxidation are extensively examined. The fast destruction of dyestuffs mediated with electrogenerated active chlorine is analyzed. Electro-Fenton and photo-assisted electrochemical methods like photoelectrocatalysis and photoelectro-Fenton, which destroy dyes by heterogeneous OH and/or homogeneous OH produced in the solution bulk, are described. Current advantages of the exposition of effluents to sunlight in the emerging photo-assisted procedures of solar photoelectrocatalysis and solar photoelectro-Fenton are detailed. The characteristics of novel combined methods involving photocatalysis, adsorption, nanofiltration, microwaves and ultrasounds among others and the use of microbial fuel cells are finally discussed.

Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes

Abstract: In recent years, there has been increasing interest in finding innovative solutions for the efficient removal of contaminants from water, soil and air. The present tutorial review summarizes the results of an extensive selection of papers dealing with electrochemical oxidation, which is proposed as an alternative for treating polluted wastes. Both the direct and indirect approaches are considered, and the role of electrode materials is discussed together with that of other experimental parameters. Apart from discussing the possibility of removing selected contaminants from water using different anodes, efficiency rates for pollutant removal have been collected, the dependence of these rates on operational conditions advantages and disadvantages determining the further full-scale commercial application.

Origin of Surface Conductivity in Diamond

Abstract: Hydrogen-terminated diamond exhibits a high surface conductivity (SC) that is commonly attributed to the direct action of hydrogen-related acceptors. We give experimental evidence that hydrogen is only a necessary requirement for SC; exposure to air is also essential. We propose a mechanism in which a redox reaction in an adsorbed water layer provides the electron sink for the subsurface hole accumulation layer. The model explains the experimental findings including the fact that hydrogenated diamond is unique among all semiconductors in this respect.