A consortium of ARPChem, Fujifilm, TOTO, Mitsubishi Chemicals and the University of Tokyo, supported by NEDO, has installed and operated, since August 2019, a demonstrator for photocatalytic water splitting and succeeded in separating and recovering high-purity „solar hydrogen“ from the mixture of hydrogen and oxygen generated by water decomposition. The system consists of a photocatalytic panel reactor  connected so that it has a light-receiving area of 100m2 and a gas separation module with a built-in separation membrane. The top of this reactor is made of transparent glass and a strontium titanate photocatalyst sheet. There is a small gap of 0.1 mm between the photocatalyst sheet and the glass through which water is supplied for the reaction. The strontium titanate photocatalyst uses sunlight UV for water splitting, with a quantum yield of almost 100%. It is manufactured by spraying photocatalyst onto the substrate. The gas separation module can maintain stable gas separation by properly controlling the gas flow rate regardless of sunlight conditions, and was operated outdoors for 65 days without losing its functionality. In addition, due to the proper design of the photocatalytic reaction system, there was no spontaneous ignition or explosion during the outdoor test. In a separate project, catalysts and process technologies are being developed to synthesize C2 to C4 olefins from hydrogen produced from this module and carbon dioxide emitted from power plants and factories.

1. NEDO news release, August 28, 2021

2. Nishiyama, H., Yamada, T., Nakabayashi, M. et al. Photocatalytic solar hydrogen production from water on a 100 m2-scale. Nature (2021). https://doi.org/10.1038/s41586-021-03907-3