Details of the Initiative

Our laboratory aims to develop photocatalysts to realize artificial photosynthesis. Photosynthesis in green plants uses light energy to produce high-energy substances (such as sugars) from water and carbon dioxide. Therefore, artificial photosynthesis can be broadly defined as the artificial creation of high-energy materials using the energy of light. From this point of view, the production of hydrogen from water and the recycling of carbon dioxide using photocatalysts can be called artificial photosynthesis.

In simple terms, photocatalysts are compounds that absorb light and cause redox reactions. In our research, we deal with inorganic semiconductors as photocatalyst materials, and work on the development of photocatalysts that can efficiently utilize light of a wide range of wavelengths in the solar spectrum.

Fossil fuels such as coal and oil are also stored solar energy from ancient times. After all, humans depend on solar energy for their lives. Artificial photosynthesis can be said to be a science and technology that can contribute to global energy and environmental problems by actively using solar energy in the present. The practical application of artificial photosynthesis will bring us closer to the realization of a sustainable society.

Comparison between photosynthesis and artificial photosynthesis: In artificial photosynthesis research, the aim is not to artificially carry out the photosynthesis of plants as it is. It is easy to understand the essence of artificial photosynthesis if we view photosynthesis from the viewpoints of “utilization of sunlight” and “storage of energy (production of high-energy compounds).”
Various photocatalytic materials: The photocatalysts used in the research have powder shapes as shown in the photograph. Powders that reflect all visible light appear white. As the wavelength of visible light that can be absorbed increases, the color of the powder changes from yellow, orange, and red to black if it absorbs all visible light.
Photocatalyst preparation: In a solid-state reaction which is one of the most common methods for the synthesis of photocatalysts, raw material powders are mixed well in a mortar and are calcined in an electric furnace. It may be necessary to keep mixing for more than 1 hour, which requires physical and grip strength.
Photocatalytic reaction experiment: A black object is the light source, and a glass reactor covered with aluminum foil is irradiated with light from above. The reactant solution and the photocatalyst powder are contained in the reactor. Generated gases are determined by an analyzer (gas chromatograph) connected to the reactor.