140th CEMS Colloquium

Title

Photocatalytic water splitting for solar hydrogen and fuels production

Abstract

Sunlight-driven overall water splitting using particulate photocatalysts is of growing interest as a means of producing green hydrogen and fuels because systems based on particulate photocatalysts can be spread over large areas using potentially inexpensive processes.1,2 The author’s group has studied various oxides, (oxy)nitrides, and (oxy)sulfides as photocatalysts for overall water splitting. Recently, by refining the preparation conditions of the photocatalyst and the loading conditions of the cocatalysts, the apparent quantum yield of overall water splitting using SrTiO3 has reached more than 90% at 365 nm, corresponding to an internal quantum efficiency close to unity.3 This observation means that particulate photocatalysts can drive the endergonic overall water splitting reaction with almost no recombination loss, as in photon-to-chemical conversion processes during photosynthesis. Using a modified SrTiO3 photocatalyst, a green hydrogen production system based on 100-m2 arrayed photocatalytic overall water splitting panels and an oxyhydrogen gas separation module was constructed and its performance and system characteristics, including safety issues, were reported.4 The hydrogen produced was also shown to be applicable to the conversion of carbon dioxide into chemical fuels.5 However, for practical solar hydrogen production, it is essential to radically improve the solar-to-hydrogen energy conversion efficiency of overall water splitting by developing photocatalysts that are highly active under visible light, and to develop suitable reaction systems for practical green hydrogen production. In my talk, recent advances and challenges in photocatalytic materials and reaction systems for mass production of green hydrogen and fuels will be discussed.

Fig. 1. A 100 m² panel reaction system based on a SrTiO₃ photocatalyst for solar hydrogen production. Reprinted from ref. 3 with permission. Copyright 2021 Springer Nature．

Recent publications:

1. Hisatomi at al., Nat. Catal., 2019, 2, 387–399. 2.Wang et al., Chem. Rev., 2020, 120, 919–985.
2. Takata et al., Nature, 2020, 581, 411–414. 4. Nishiyama et al., Nature 2021, 598, 304–307.
3. Yamada et al., ACS Eng. Au 2023, 3, 352–363.

Contact

email: yasano@riken.jp
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