Z-scheme photocatalyst systems employing Rh- and Ir-doped metal oxide materials for water splitting under visible light irradiation. (24th April 2019)

• Record Type: Journal Article
• Authors: Kudo, Akihiko; Yoshino, Shunya; Tsuchiya, Taichi; Udagawa, Yuhei; Takahashi, Yukihiro; Yamaguchi, Masaharu; Ogasawara, Ikue; Matsumoto, Hiroe; Iwase, Akihide
• Is Part Of: Faraday discussions. Volume 215(2019)
• Page Start: 313
• Page End: 328
• Publication Date: 2019-04-24
• Subjects: Chemistry -- Periodicals; Metallurgy -- Periodicals; Electrochemistry -- Periodicals; 540
• DOI: 10.1039/c8fd00209f
• Languages: English
• ISSNs: 1359-6640

Abstract

Abstract : Z-scheme systems for water splitting were successfully developed by employing Rh- and Ir-doped metal oxides with SrTiO3 :Rh and BiVO4 photocatalysts. 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): BaTa2 O6 :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 BaTa2 O6 :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 Fe 3+/2+ one. The combination of SrTiO3 :Ir with SrTiO3 :Rh gave an activity when the [Co(bpy)3 ] 3+/2+ and Fe 3+/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 Fe 3+/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 Rh 3+ and Ir 3+ 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.