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Z-scheme photocatalyst systems employing Rh- and Ir-doped metal oxide materials for water splitting under visible light irradiation

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Abstract

Various types of Z-scheme systems for water splitting under visible light irradiation were successfully developed by employing Rh- and Ir-doped metal oxide powdered materials with relatively narrow energy gaps (EG): BaTa2O6:Ir,La (EG: 1.9–2.0 eV), NaTaO3:Ir,La (EG: 2.1–2.3 eV), SrTiO3:Ir (EG: 1.6–1.8 eV), NaNbO3:Rh,Ba (EG: 2.5 eV) and TiO2:Rh,Sb (EG: 2.1 eV), with conventional SrTiO3:Rh (an H2-evolving photocatalyst) or BiVO4 (an O2-evolving photocatalyst), and suitable electron mediators. The Z-scheme systems were classified into three groups depending on the combination of H2- and O2-evolving photocatalysts and electron mediator. The Z-scheme systems combining BaTa2O6:Ir,La with BiVO4, and NaTaO3:Ir,La with BiVO4 were active when a [Co(bpy)3]3+/2+ redox couple was used rather than an Fe3+/2+ one. The combination of SrTiO3:Ir with SrTiO3:Rh gave an activity when the [Co(bpy)3]3+/2+ and Fe3+/2+ redox couple ionic mediators were used. The Z-scheme systems combining NaNbO3:Rh,Ba and TiO2:Rh,Sb with SrTiO3:Rh showed activities by using the [Co(bpy)3]3+/2+ and Fe3+/2+ redox couples and also via interparticle electron transfer by just contact with/without reduced graphene oxide (RGO). These suitable combinations can be explained based on the impurity levels of doped Rh3+ and Ir3+ toward the redox potentials of the ionic mediators for the Z-scheme systems employing ionic mediators, and p-/n-type and onset potentials of the photocurrent in the photoelectrochemical properties of those photocatalyst materials for the Z-scheme systems working via interparticle electron transfer.

Graphical abstract: Z-scheme photocatalyst systems employing Rh- and Ir-doped metal oxide materials for water splitting under visible light irradiation

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Publication details

The article was received on 27 Nov 2018, accepted on 24 Jan 2019 and first published on 25 Jan 2019


Article type: Paper
DOI: 10.1039/C8FD00209F
Citation: Faraday Discuss., 2019, Advance Article

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    Z-scheme photocatalyst systems employing Rh- and Ir-doped metal oxide materials for water splitting under visible light irradiation

    A. Kudo, S. Yoshino, T. Tsuchiya, Y. Udagawa, Y. Takahashi, M. Yamaguchi, I. Ogasawara, H. Matsumoto and A. Iwase, Faraday Discuss., 2019, Advance Article , DOI: 10.1039/C8FD00209F

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