We create innovative materials that can contribute to low-carbon society.

Functional Inorganic Materials 

(1) Oxygen Ion Conductor

Electrolyte for solid oxide fuel cell (SOFC) needs to have much higher oxygen ion conductivity than electon and hole conductivity. At present, Zr0.87Y0.13O2 is widely used for the electrolyte, but use of the electrolyte needs high temperature, 1000oC for the operation. The La0.8Sr0.2Ga0.9Mg0.1O3(LSGM) developed in our laboratory enabled the power generation at 600oC. Currently, in addition to perovskite oxides, we are developing high-oxygen ion conductors with a new composition. High oxygen ion conductors can be applied to automotive oxygen sensors as only O2- moves in solids and not electrons.
(2) Low-temperature Solid Oxide Fuel Cell

Fuel cells are attracting attention as a power generation system with high energy conversion efficiency and low CO2 emissions. Among the fuel cells, we are developing a solid oxide fuel cell(SOFC) that is the most stable and has few fuel restrictions. In recent years, we succeeded in operating SOFC at low temperatuee using LSGM electrolyte. Currently, we are developing the LSGM thin films as well as highly active electrocatalysts in order to operate at much lower temperatures.
(3) Oxide Anode and Highly Reliable SOFC

SOFC can generate electricity using hydrogen as fuel, and it is expected to be effective for global warming countermeasures because it emits less CO2 at the time of electricity generation. Although the output is inferior to that of conventional Ni-base anode, we are examining an oxide anode that shows overwhelming durability against oxidation and sulfur poisoning due to long-term use. We gound a mixed anode of CeO2-based oxide and LaFe3-based oxide. It is highly expected that city gas can be used directly for the electricity generation.
(4) Highly Active Electrocatalyst for Alkaline Direct Ethanol Fuel Cells

Since direct ethanol fuel cells (DEFC) use ethanol as a fuel, they have advantages in both fuel safety and storage ease compared to hydrogen fueled polymer electrolyte fuel cells (PEFCs). In particular, the development is expected as a power source for mobile devices and transportation devices. We are developing an electrode catalyst that substitutes platinum as an electrode catalyst of DEFC using an alkaline electrolyte memberane.
(5) Solid Oxide Electrolysis Cell (SOEC)

High-temperature steam electrolysis (Solid Oxide Electrolysis Cell, SOEC) attracts attention because it can electrolyze water with high efficiency and obtain hydrogen by using waste heat. We have found that high hydrogen generation rate can be realized by using LaGaO3-based oxide which is high oxygen ion conductor as solid electrolyte. Currently, not only steam electrolysis but also CO electrolysis is being considered. CO obtained by electrolyzing CO2 can be used as a fuel for fuel cells, and it can be expected as an environmentally-friently technology.
(6) Gas Sensor for Environment Detection (Current Detection Type CO Sensor)

Carbon monoxide gas is a highly toxic gas, which causes serious damage to human. Thus, there is a need for a sensor that can detect CO gas. We are developing a current detection type CO sensor using an oxygen ion conductor as an electrolyte.
(7) Li-ion Secondary Battery Material (Dual Carbon Batteries)

Hybrid vehicles (HV) and electric vehicles (EV) are in widespread use. The performance of the battery is not sufficient for their use jusy by upsizing it which is currently used in mobile phones and notebook computers, and the improvement of the performance of the secondary batteries (rechargeable batteries) is strongly required.
We are investigating dual carbon batteries that compensate for the drawbacks of conventional Li-ion batteries that use rare metals for the cathode, and that are superior in high-speed charge and discharge. In this battery, high operating voltage can be obtained by using graphite for both electrodes. It can be expected to be environmentally-friendly and cost-effective, and the risk of ignition is also much smaller than conventioanl Li-ion batteries. However, because there is a problem in the recyclability, we examine the effects of pretreatment on the cathode, and aim to improve the charge-discharge recyclability and the capacity.
(8) Li-Air Secondary Battery Materials

Currently, the development of high-capacity batteries is desired as a power source for electric vehicles (EVs). A Li-air secondary battery uses oxygen in air as a cathode active material and Li as a anode active material, and has a large theoretical capacity and is drawing attention as a next-generation battery to replace the current Li-ion battery. However, the degradation during the charge-discharge cycles is now a major issue. To put this battery into practical use, we examine the capacity and cycle characteristics of the battery using an organic solvent as the electrolyte and mesoporous MnO2 as a cathode material. We also investigate the cause of deterioration of Li as an anode material after charging and discharging. In addition, we study gel electrolytes that can suppress Li dendrite phenomenon and electrolyte volatilization.
(9) Metal-Air Secondary Battery Materials using Oxygen Ion Conductors

Metal-air batteries are attracting attention as high-energy density seconday batteries because they can ignore the weight of the cathode and increase the weight on the anode. In metal-air batteries using conventional solution-based electrolytes, the problem was that reversibility was poor due to the reaction and decomposition of the electrolyte with metals. We have newly developed a metal-aire secondary battery that performs metal redox using a chemically stable oxygen ion conductor as the electrolyte. In the batteries using Fe as the active material for anode, it has been confirmed that a charge-discharge capacity of 97% of the theoretical value can be obtained, and stable charge-discharge can be repeated. We also examine Mg-air batteries that use Mg, which has a very high theoretical energy density, for the anode.
(10) Hydrogen Storage Material

Hydrogen is expected as a next-generation energy carrier, and there is curretly a need for technological development to store and transport hydrogem. However, because hydrogen is a gas and is not suitable for storage, it is desirable to develop materials that can store hydrogen. We focused on cheap Mg, which has a large hydrogen storage density and abundant resources. However, Mg has the disadvantage that the reaction rate is slow and does not react at low temperatures. In order to overcome the drawback, we investigate the surface catalysts and additives of various elements that can occlude and release hydrogen at relatively low temperatures and increase the hydrogen storage capacity.

Heterogeneous Catalysts

(11) Particulate Matter(PM) Oxidation Catalyst

Diesel engines are superior in thermal efficiency compared to gasoline enegines, emit less CO2, and are drawing attention as promising internal combustion engines for global warming countermeasures. However, it emits carbon fine particles called particulate matter (PM), which may cause adverse effects on the environment and the human body. Therefore, we develop a catalyst that oxidizes and removes the PM at low temperature. Examples are Fe-based oxide catalyst which oxidizes PM by reducing Fe.
(12) Direct NOx Decomposition Catalyst

Exhaust gases emitted from internal combustion engines such as automobiles include air pollutants such as NOx, PM, CO2, and SOx. No effective removal technology has been established for NOx, and many measures are being considered. Since NOx is always generated by the combustion reaction at 1500oC or higher in air, the only way for the removal is post-treatment of the exhaust gas. We found that Y2O3-based catalyst could decompose NO directly in a full conversion at 850oC (2NO -> N2 + O2). We develop a catalyst that maintains NO decomposition activity even in actual exhaust gas.

(13) Propane Steam Reforming

To realize hydrogen society, efficient hydrogen production technology is required. We investigate a catalyst for propane steam reforming which generates more hydrogen even at low temperatures. We also examine a hydrogen separation membrane to separate the generated hydrogen.
(14) Direct Synthesis of H2O2

Since the decomposition products from H2O2 are water and oxygen, its industrial use is increasing as an oxidant with low environmental impact. However, the complexity of the current H2O2 synthesis process makes it an expensive oxidant. We investigate direct synthesis process of H2O2, which directly oxidizes H2, using Pd-Au/TiO2 catalysts and colloidal Pd-Ad catalysts.
(15) Photocatalyst for Hydrogen Production

Photocatalysts are semiconductor materials that use light energy to split water into hydogen and oxygen. The production of hydrogen using photocatalyst is the ultimate environmentally-friendly method, but still need to find more active materials.

Dye-modified Photocatalyst

Previous studies have focused on research using UV light, but UV light is only about 5 to 6% of sunlight. We focused on hydrogen production using both UV and visible light. The metal complex dye (Cr:tetraphenyl porphyrin)-modified inorganic semiconductor was found to significantly produce hydrogen and oxygen from water.