Kazunari DOMEN

The University of Tokyo

Keynote Speaker


Kazunari Domen received B.S. (1976), M.S. (1979), and Ph.D. (1982) honors in chemistry from the University of Tokyo. Dr. Domen joined Chemical Resources Laboratory, Tokyo Institute of Technology in 1982 as Assistant Professor and was subsequently promoted to Associate Professor in 1990 and Professor in 1996. Moving to the University of Tokyo as Professor in 2004, and Cross appointment with Shinshu University as Special Contract Professor in 2017. University Professor of the University of Tokyo in 2019.

Domen has been working on overall water splitting reaction on heterogeneous photocatalysts to generate clean and recyclable hydrogen. In 1980, he reported NiO-SrTiO3 photocatalyst for overall water splitting reaction, which was one of the earliest examples achieving stoichiometric H2 and O2 evolution on a particulate system. In 2005, he has succeeded in overall water splitting under visible light (400 nm<λ<500nm) on GaN:ZnO solid solution photocatalyst.

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A Large Scale Solar Hydrogen Production by Photocatalytic Water Splitting

Kazunari DOMEN

1 Research Initiative for Supra-Materials, Shinshu University, Japan
2 Office of University Professors, The University of Tokyo, Japan


Sunlight-driven water splitting using particulate photocatalysts has been attracting growing interest because such systems can be spread over large areas by potentially inexpensive processes [1]. In fact, a solar hydrogen production system based on 100-m2 arrayed photocatalytic water splitting panels and an oxyhydrogen gas-separation module was built, and its performance and system characteristics including safety issues were reported recently [2]. Nevertheless, it is essential to radically improve the solar-to-hydrogen energy conversion efficiency (STH) of particulate photocatalysts and develop suitable reaction systems. In my talk, recent progress in photocatalytic materials and reaction systems will be presented.

The author’s group has studied various semiconductor materials as photocatalysts for water splitting. Recently, the apparent quantum yield (AQY) of SrTiO3 has been improved to more than 90% at 365 nm, equivalent to an internal quantum efficiency of almost unity, by refining the preparation of the photocatalyst and cocatalysts [3]. This observation means that particulate photocatalysts can drive the endergonic overall water-splitting reaction with almost no recombination loss. For practical solar hydrogen production, it is essential to develop photocatalysts that are active under visible light. Recently, Ta3N5 [4], Y2Ti2O5S2 [5], TaON [6], and BaTaO2N [7] were found to be active in photocatalytic overall water splitting via one-step excitation under visible light. In these achievements, the synthesis of well-crystallized semiconductor particles and the loading of composite cocatalysts were important for improving photocatalytic activity. It is also possible to combine hydrogen evolution photocatalysts (HEPs) and oxygen evolution photocatalysts (OEPs) and decompose water into hydrogen and oxygen via two-step excitation. Such a process is also known as Z-scheme. Particulate photocatalyst sheets consisting of La- and Rh-codoped SrTiO3 as the HEP and Mo-doped BiVO4 as the OEP immobilized onto Au and C layers split water into hydrogen and oxygen with STH values exceeding 1.0% [8, 9]. Some other (oxy)chalcogenides and (oxy)nitrides with long absorption edge wavelengths are also applicable to Z-schematic photocatalyst sheets [10] and hold the promise of realizing greater STH values.


[1] Hisatomi et al., Nat. Catal. 2, 387 (2019).

[2] Nishiyama et al., Nature 598, 304 (2021).

[3] Takata et al., Nature 581, 411 (2020).

[4] Wang et al., Nat. Catal. 1, 756 (2018).

[5] Wang et al., Nat. Mater. 18, 827 (2019).

[6] Xiao et al., Angew. Chem. Int. Ed. 134, e202116573 (2022).

[7] Li et al., ACS Catal. 12, 10179 (2022).

[8] Wang et al., Nat. Mater. 15, 611 (2016).

[9] Wang et al., J. Am. Chem. Soc. 139, 1675 (2017).

[10] Hisatomi et al., Catal. Sci. Technol. 8, 3918 (2018).

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