Research
Materials and processes pioneered by plasma and SDGs
Over 99% of outer space is made of plasma. The sun is also plasma. Plasma is the fourth state following solids, liquids, and gases, and is in a high-energy state in which ions and electrons move around freely. Candle flames and lightning are also plasma in our daily lives. In our laboratory, we study low-pressure, atmospheric pressure, and low-temperature plasma in liquids, and by understanding and controlling the plasma generated in liquids, we can use it for advanced chemical processes and synthesize new materials. I am. We aim to realize a sustainable recycling-oriented society through these processes and materials. We are also working on making the technology usable not only on the ground but also in space (the moon). We will contribute to the achievement of the SDGs through joint research with laboratories within the department, research institutes such as universities inside and outside the university, and companies.
Make diamonds by generating plasma in alcohol
Keywords: diamond, CVD, plasma in microwave liquid
Diamond is an attractive material with many excellent properties such as the highest hardness and thermal conductivity of all substances. In recent years, it is expected to be applied as an electrode that reduces CO2. However, the current mainstream synthesis method for diamond has problems such as slow film formation rate and film formation area. Our laboratory is focusing on the microwave plasma method to solve these problems. In-liquid plasma is a technology that generates plasma in bubbles in a liquid. In fact, using this technology, we succeeded in synthesizing diamond 100 times faster than the conventional technology. Currently, we are working on increasing the area of the diamond film for practical use of this technology.
(Yusuke Tominaga, Akihiro Uchida)
Diamond composite copper-plated heat-dissipating material for next-generation semiconductors
Keywords: diamond, copper, heat sink material, high thermal conductivity, amino group modification
With the increase in speed and high integration of semiconductor devices and the miniaturization of electrical and electronic devices, heat generation and high temperature of electronic components have become remarkable problems. Therefore, there is a demand for a heat sink material that has high thermal conductivity and efficiently dissipates heat. Among them, a composite material of a copper matrix having a relatively high thermal conductivity (400 W / mK) at a low cost and a diamond particle having the highest thermal conductivity (up to 2,000 W / mK) has been studied. There is. However, copper and diamond have poor wettability, and there is a problem that high thermal conductivity cannot be obtained because a large contact thermal resistance is generated at the interface between them. Therefore, in this study, amino groups were modified on the surface of diamond particles in order to enhance the affinity between the two. At that time, we aimed to increase the amount of modification of the amino group by generating radicals using a photocatalytic reaction. A diamond / copper composite is actually produced using amino group-modified diamond particles, with the aim of achieving high thermal conductivity.
(Kazuki Kato, Yuta Fujii)
Development of simple water purification technology by using photocatalyst net
Keywords : titanium dioxide , water purification, developing countries, polypropylene
Drinking water in developing countries is polluted with bacteria such as E. coli and Salmonella, however developing countries do not have the financial resources to build water purification facilities. Therefore, an inexpensive method to purify water is highly needed. We focused on titanium oxide (TiO2), which is an inexpensive photocatalyst and destroys bacteria by constantly oxidizing them after they destroy their cell membranes due to the powerful oxidizing power of reactive oxygen species, which are formed under UV light irradiation. Therefore, we aimed to create a titanium dioxide supported net that can easily purify water.
(Dylan Shun Izuma )
Liquid fertilizer with algae-proofing effect by underwater plasma made from air and water
Keywords: liquid fertilizer, algae prevention effect, plasma function water, mechanism elucidation
Since ancient times, it has been said that in Japan, a good harvest occurs in years when there is a lot of lightning. Thunder is called "lightning bolt" by writing "wife" in "rice" and is one of the words that expresses this legend. It has been found that lightning creates nutrient sources for plants in raindrops from the air, they fall on the surface of the earth, and rain acts as a liquid fertilizer for a good harvest. Therefore, in our laboratory, we make a special liquid fertilizer "plasma functional water" from air and water by "underwater plasma method" that imitates this "lightning bolt". In the course of research, it has become clear that this "plasma functional water" has not only the "effect of liquid fertilizer" for growing plants, but also the "anti-algae effect" that can prevent the growth of algae. Therefore, we are engaged in research activities with the goal of "elucidating the mechanism of algae-proofing effect" as to why algae growth can be prevented and "enlarging the device" with the aim of putting an underwater plasma generator into practical use. I'm out.
(Ken Mizoi, Mao Sasaki)
Microwave absorber material for the development of IoT
Keywords: microwave absorbing material, oxygen-deficient titanium oxide , Beyond 5G
In recent years, with the development of communication technologies such as 5G and 6G, health hazards due to microwave leakage and information leakage from electronic devices have become problems. Therefore, a method for producing a microwave absorber easily and inexpensively is attracting attention. Oxygen-deficient TiO2 is thought to absorb microwaves through interaction with an electric field originating from a chaotic interface. In our laboratory, we have succeeded in producing oxygen-deficient TiO2 at normal temperature, pressure, and short time by treating titanium oxide particles by the underwater plasma method. Therefore, in this research, we will contribute to the development and development of communication equipment to achieve high performance by developing materials that support a wide range of frequencies using the underwater plasma method.
(Yuta Fujii)
Solar catalyst aimed at carbon recycling
Keywords: carbon recycling, CO2 reduction, underwater plasma method, solar thermal catalyst
Mankind is still heavily dependent on fossil fuel consumption, and CO2 is still constantly being emitted to the earth. Since CO2 is concerned about global warming and adverse effects on ecosystems, CO2 reduction technology that captures CO2 as a resource and converts it into a useful resource is attracting attention. In particular, a material called a solar thermal catalyst is drawing attention. As the name implies, this catalyst uses the heat of sunlight. Oxygen deficiency is generated in the metal oxide by heating, and the oxygen deficiency acts as an active site and reduces CO2 to CO. Photocatalysts can use only about 6% of sunlight, while solar thermal catalysts can use more than 50% of sunlight, including visible light. If this catalyst is put into practical use, it can become a CO2 reduction technology with zero energy cost. In our laboratory, we succeeded in improving the activity by increasing the oxygen deficiency of titanium oxide, which is a photocatalyst, using a method called the underwater plasma method.