Methane reforming is an important technology which reforms methane that is an abundant resource into more valuable hydrogen and carbon monoxide. The product, a mixed gas of hydrogen and carbon monoxide, is called syngas, and is an important material that is used as a raw material for various industrial products. Although there are multiple gases used for methane reforming, our laboratory is working on the most difficult reaction using carbon dioxide. In addition, this is a promising reaction in terms of recycling carbon dioxide which is one of the greenhouse gases causing global warming. Contrary to the previous research reactions caused by heat, we aim to use renewable energy like solar light to drive dry reforming of methane.

Photocatalysis research was initiated by Honda and Fujishima in the field of electrochemistry, since then, the concept has been extended to the particulate catalysis systems referred to as microphotoelectrochemical cells, in which the oxidation and reduction sites are located on a particle. It is difficult to elucidate the mechanism of the powdered catalysts due to the mixture of mediating ions, photogenerated electrons, holes, and reaction sites. Therefore, we developed the gas-phase photoelectrochemical (GPEC) system to separate the oxidation and reduction sites by using oxygen ions conductors to design a high-performance photocatalyst. Currently, we are studying oxygen ion mediated dry reforming and steam reforming of methane, and in the future, we plan to expand our research to other ion mediated reactions.

Two-dimensional (2D) materials have attracted a lot of attention due to its unique properties. We are studying boron-based nanosheets which can be synthesized by exfoliating of magnesium diboride (MgB2) under the collaboration with Prof. Kondo’s group in Tsukuba University. In particular, hydrogen boride nanosheets (HB sheets), a new 2D material reported recently, is expected to have various applications because of its unique reducing ability and photoinduced hydrogen release property.

Photocatalytic water splitting is one of the most attractive ways to harvest the unlimited solar energy. However, most photocatalysts with desirable band structures are UV light active, which is a pity because the most intense part of the sunlight is visible light. We are developing the visible light active photocatalyst with the goal of enhancing the overall photoconversion efficiency. We currently study the nanoclusters grafted photocatalyst using the concept of interfacial charge transfer, and mixed valence metal oxide for CO2 reduction. By combining bulk and surface semiconductor modification, photoelectrochemistry and in-situ measurements, we provide new useful insights to push forward state-of-the-art of the research, and make great impacts to industry.

Electrochemistry is a promising way for an advance application to overcome carbon waste emission. We are developing electrode materials and catalysts for electrochemical CO2 reduction, which converts carbon dioxide into useful products using electricity generated from renewable energy sources and other sources. We are focusing on metal alloys and metal sulfides as the main electrocatalyst. We are designing the material by conducting surface modification, tuning morphology and crystal structure to achieve a better activity. In addition, our group also approaches on computational study such as machine learning and first principal calculation for a better material design and prediction of catalytic activity.

Hydrothermal electrochemical flow reactor (HEFR) was created through joint research between Earth Life Science Institute (ELSI) and our laboratory. Using this device, we research the synthesis of new catalysts useful for electrochemical reactions such as CO2 reduction and O2 evolution. Since HEFR enables us to change the solution temperature and pressure independently, it is expected we can synthesize catalysts with morphologies and phases that cannot be synthesized by ordinary synthesis.