Graduate School of Science and Engineering Science of Environment and Mathematical Modeling

<2> "Hydrogen energy systems" and the "ammonia economy"

To achieve a hydrogen energy system, it will be necessary to establish the basic technology to use "ammonia" as a key material for the storage, transport and use of hydrogen. On the other hand, ammonia is used not only in fertilizer and chemicals, but also increasingly in applications as a reducing agent of NOXs and heat transfer medium. If ammonia can be positioned as a key material of a cooperative system for both industrial application and hydrogen energy system, it is possible to built "ammonia economy" as a new economic system. To turn this idea into reality, we have proposed a new method-"electrolytic synthesis of ammonia under atmospheric pressure," which is simple, has low energy cost and can be used in place of the conventional Haber-Bosch process, and we are proceeding with the research and development of this method.

<3> Creating new functional materials

We have proposed a novel method of creating a wide variety of new functional materials, including "rare earth-transition metal alloy films," "carbon films," "nano-powders" and so on, with an electrochemical process using molten salt as a reaction medium, and have proven the possibility of such a method. An overview is given of a few examples below.

Creating functional rare earth-transition metal alloy films
When nickel or cobalt are used as cathodes and cathodically polarized in molten salt containing rare earth ions, various rare earth-transition metal alloy films are formed on the cathodes. In addition, when the obtained films are used as anodes and anodically polarized in molten salt, the morphologies and compositions of the obtain film can be precisely controlled by electrolysis conditions (applied potentials, current densities, molten salt compositions. etc). By using this method, it is possible to obtain the desirable composition and porosity of the alloy films. The lab is working to create various types of alloy films with the goal of expanding applications of this technique to magnetic, electrode and catalytic materials and microreactors.

Forming carbon films by electrochemical processes
When copper or aluminum are used as cathodes and cathodically polarized in molten salt containing carbonates, various carbon films are formed on the cathode surface. The structure of this film is controlled by electrolysis conditions such as substrate materials, applied potentials, current densities and so on. Our research is trying to understand more quantitatively the relationship between the conditions of electrolysis and the structures of the obtained carbon films, and is furthermore seeking out the optimal conditions for getting carbon films suited to individual applications, such as electric double layer capacitors, batteries and moreover catalysts. We are also working on the electrochemical formation of carbonaceous composite films with the objective of achieving new functions.

Producing functional powders by plasma induced electrolysis
Molten salts containing metal ions are used as electrolytes for plasma induced electrolysis. When a voltage of DC 200 V is applied between the anode and the cathode whose tip is positioned above the bath surface, a plasma is induced between the cathode and the melt under 1 atm of Ar to produce the corresponding metallic powders in the melt. Once the atmosphere is turned to plasma, the electric current can flow continuously even with just some tens of volts, so that the microparticles are produced continuously. Using this principle, functional micro- or nano-particles of various metals and compounds are possible to produce, which are suited to individual applications like magnetic recording media, photocatalysts, pigments, battery electrodes, electrochemical capacitors, catalysts and so on.