Fig. 1. Photocatalytic water-splitting activities. (a) Time course of H₂ and O₂ evolution on SrTiO₃:Al loaded with various cocatalysts during photoirradiation. Left, loaded with Rh (0.1 wt%)/Cr₂O₃ (0.05 wt%) by two-step photodeposition. Middle, loaded with Rh (0.1 wt%)/Cr₂O₃ (0.05 wt%)/CoOOH (0.05 wt%) by three-step photodeposition. Right, loaded with Rh (0.1 wt%)-Cr (0.1 wt%) oxide by co-impregnation. (b) Ultraviolet-visible diffuse reflectance spectrum of bare SrTiO₃:Al (black solid line) and wavelength dependence of external quantum efficiency (EQE) during water splitting on Rh (0.1 wt%)/Cr₂O₃ (0.05 wt%)/CoOOH (0.05 wt%)-loaded SrTiO₃:Al (red symbols).

Fig. 2. Transmission electron microscopy. (a) Selected-area electron diffraction pattern obtained from SrTiO₃:Al loaded with Rh (0.1 wt%)/Cr₂O₃ (0.05 wt%)/CoOOH (0.05 wt%). (b) Corresponding transmission electron microscopy image of a particle. (c) Particle morphology and crystal orientation.

Fig. 3. Simulations of photocarrier distributions in SrTiO₃:Al particles. (a) Mapping of conduction-band energy, E_c. (b) Density of electrons (e^-), n. (c) Density of holes (h⁺), p. (d) Energy band diagram. (e) Electron and hole densities as functions of position (x′, y′) with work function difference ΔW_el = 0.2 eV. (f) Effect of ΔW_el on electron-to-hole-density ratio at the {100} and {110} facets.