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Issue 7, 2018
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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

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Abstract

Bi4NbO8Cl with a Sillén–Aurivillius type perovskite structure has recently been 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 potentials 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 the resultant photocatalytic activity. We found experimentally and theoretically that both M and X substitutions have little influence on the electronic structures, providing similar valence band maximums (VBMs) and band gaps to those of Bi4NbO8Cl. They all functioned as stable O2-evolving photocatalysts 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 using a revised lone pair (RLP) model, thus explaining at least partly why the O-2p orbitals are elevated in energy.

Graphical abstract: 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

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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, 2018,6, 3100-3107
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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, 6, 3100
    DOI: 10.1039/C7TA08619A

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