Z‑Schematic\nWater Splitting on Photocatalyst\nSheets Composed of Transition-Metal-Doped Metal Oxides with Long Wavelength\nVisible Light Responses and a Conductive Polymer

We successfully developed Z-schematic photocatalyst sheets\nconsisting\nof transition-metal-doped oxide materials responding to visible light\nwith long wavelengths as O<sub>2</sub>-evolving photocatalysts and\npoly-3,4-ethylenedioxythiophene (PEDOT) of a conductive polymer as\na solid-state hole transporter combined with Ru-loaded SrTiO<sub>3</sub>:Rh as a H<sub>2</sub>-evolving photocatalyst for water splitting\nunder visible light irradiation by a facile drop-casting method. TiO<sub>2</sub>:Rh,Sb (EG: 1.9–2.3 eV), SrTiO<sub>3</sub>:Ru,Sb (EG:\n1.8 eV), and SrTiO<sub>3</sub>:Ir,Sb (EG: 1.6–1.8 eV) were\nemployed as O<sub>2</sub>-evolving photocatalysts that are responsive\nto visible light with longer wavelengths than BiVO<sub>4</sub> (BG:\n2.4 eV) of a conventional O<sub>2</sub>-evolving photocatalyst. The\nZ-scheme photocatalyst sheets composed of these O<sub>2</sub>-evolving\nphotocatalysts split water into H<sub>2</sub> and O<sub>2</sub> in\na stoichiometric amount under visible light irradiation at room temperature\nand 1 atm even without pH adjustment. In particular, the photocatalyst\nsheet composed of TiO<sub>2</sub>:Rh,Sb showed the highest Z-schematic\nwater splitting activity under visible light among the sheets composed\nof other transition-metal-doped photocatalysts. Furthermore, the control\nexperiments using 3-type light emitting diodes (<i>λ</i> = 450, 525, and 590 nm) revealed that the new Z-scheme photocatalyst\nsheet using TiO<sub>2</sub>:Rh,Sb could utilize visible light with\nlong wavelengths compared with that using BiVO<sub>4</sub>.