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Strong hybridization between Bi-6s and O-2p orbitals in Sillén–Aurivillius perovskite Bi4MO8X (M = Nb, Ta; X = Cl, Br), visible light photocatalysts enabling stable water oxidation

Abstract

Bi4NbO8Cl with a Sillén–Aurivillius type perovskite structure has been recently demonstrated to stably and efficiently oxidize water under visible light, possibly related to its unique valence band with O-2p orbitals located at unusually high potential compared with conventional oxides. Here we study a series of isostructural oxyhalides Bi4MO8X (M = Nb, Ta; X = Cl, Br) to examine how the cation and anion substitution affects the band structure and resultant photocatalytic activity. We found experimentally and theoretically that both M and X substitutions provide little influence on the electronic structures, providing similar valence band maximums (VBMs) and band gaps with Bi4NbO8Cl. They all worked as a stable O2-evolving photocatalyst under visible light without suffering from self-oxidative deactivation, as opposed to BiOBr. DFT calculations further revealed a fairly strong hybridization between the Bi-6s orbitals and the O-2p orbitals, which is interpreted in terms of a revised lone pair (RLP) model, thus explaining at least partly why the O-2p orbitals are elevated in energy.

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Publication details

The article was received on 29 Sep 2017, accepted on 02 Jan 2018 and first published on 03 Jan 2018


Article type: Paper
DOI: 10.1039/C7TA08619A
Citation: J. Mater. Chem. A, 2018, Accepted Manuscript
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    Strong hybridization between Bi-6s and O-2p orbitals in Sillén–Aurivillius perovskite Bi4MO8X (M = Nb, Ta; X = Cl, Br), visible light photocatalysts enabling stable water oxidation

    H. Kunioku, M. Higashi, O. Tomita, M. Yabuuchi, D. Kato, H. Fujito, H. Kageyama and R. Abe, J. Mater. Chem. A, 2018, Accepted Manuscript , DOI: 10.1039/C7TA08619A

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