Efficient Separation of Photoexcited Charge at Interface between Pure CeO2 and Y3+-Doped CeO2 with Heterogonous Doping Structure for Photocatalytic Overall Water Splitting

Honghao Hou; Hirohisa Yamada; Atsumi Nitta; Yoshinori Murakami; Nobuo Saito

doi:10.3390/ma14020350

Efficient Separation of Photoexcited Charge at Interface between Pure CeO₂ and Y³⁺-Doped CeO₂ with Heterogonous Doping Structure for Photocatalytic Overall Water Splitting

Materials (Basel). 2021 Jan 12;14(2):350. doi: 10.3390/ma14020350.

Authors

Honghao Hou¹, Hirohisa Yamada², Atsumi Nitta³, Yoshinori Murakami⁴, Nobuo Saito¹

Affiliations

¹ Department of Materials Science and Technology, Nagaoka University of Technology, Nagaoka 940-2188, Japan.
² Department of Chemical Engineering, National Institute of Technology Nara College, Nara 639-1080, Japan.
³ Department of Environmental Materials, National Institute of Technology Niihama College, Niihama 792-8580, Japan.
⁴ Department of Materials Engineering, National Institute of Technology Nagaoka College, Nagaoka 940-8532, Japan.

Abstract

Enhancement of photoexcited charge separation in semiconductor photocatalysts is one of the important subjects to improve the efficiency of energy conversion for photocatalytic overall water splitting into H₂ and O₂. In this study, we report an efficient separation of photoexcited charge at the interface between non-doped pure CeO₂ and Y³⁺-doped CeO₂ phases on particle surfaces with heterogeneous doping structure. Neither non-doped pure CeO₂ and homogeneously Y³⁺-doped CeO₂ gave activities for photocatalytic H₂ and O₂ production under ultraviolet light irradiation, meaning that both single phases showed little activity. On the other hand, Y³⁺-heterogeneously doped CeO₂ of which the surface was composed of non-doped pure CeO₂, and Y³⁺-doped CeO₂ phases exhibited remarkable photocatalytic activities, indicating that the interfacial heterostructure between non-doped pure CeO₂ and Y³⁺-doped CeO₂ phases plays an important role for the activation process. The role of the interface between two different phases for activated expression was investigated by selective photo-reduction and oxidation deposition techniques of metal ion, resulting that the interface between two phases become an efficient separation site of photoexcited charge. Electronic band structures of both phases were investigated by the spectroscopic method, and then a mechanism of charge separation is discussed.

Keywords: Y3+-doped CeO2 photocatalyst; charge separation at interface; heterogeneous doping structure; overall water splitting.