Fig. 1. (Color online) (a) Schematic structure of cubic ABX₃ perovskite unit cell, and (b) the extended tridimensional structure of perovskites formed by the corner-linked octahedral.

Fig. 2. (Color online) Schematic illustration of the basic reaction mechanism of the overall water splitting on a semiconductor (a), and uphill reaction process of photocatalytic water splitting (b). Reprinted from Ref. [44].

Fig. 3. (Color online) (a) Schematic illustration of water splitting using a TiO₂ photoelectrode. Reprinted from Ref. [44]. (b) H-type glass container for the separate evolution of H₂ and O₂ using a TiO₂ thin film photocatalyst device (TiO₂ side, 1.0 M NaOH aqueous solutions; Pt side, 0.5 M H₂SO₄ aqueous solution). Reprinted from Ref. [54].

Fig. 4. (Color online) Schematic illustration of the main processes of the photocatalytic overall water splitting reaction.

Fig. 5. (Color online) Schematic illustration of (a) the band structure and (b) DOS (density of states) plots of LCTO, (c) typical time course of photocatalytic H₂ evolution reaction, (d) photocatalytic O₂ evolution rate as a function of the cutoff wavelength of incident light. Reprinted from Ref. [69].

Fig. 6. (Color online) (a) Schematic diagram of band positions relative to the vacuum level and NHE for the BFO50-STO50 film. A, B, and C represent the photoexcited carriers relaxation and recombination processes. (b) Current density-potential curves of BFO, BFO75-STO25, BFO50-STO50, BFO25-STO75, and STO films. Reprinted from Ref. [81].

Fig. 7. (Color online) The morphology engineering strategy for SrTiO₃ nanocrystals. (a–c) The morphology of 6-facet SrTiO₃ nanocrystals. (d) The structure of the {001} facet of SrTiO₃. (e) The schematic description of changing SrTiO₃ nanocrystals from 6-facet to 18-facet. (f–h) The morphology of 18-facet SrTiO₃ nanocrystals. (i) The structure of the {110} facet of SrTiO₃. Reprinted from Ref. [85].

Fig. 8. (Color online) (a) UV–vis absorption spectra and (b) typical time course of photocatalytic H₂ evolution reaction of c-NaNbO₃ (cubic NaNbO₃) and o-NaNbO₃ (orthorhombic NaNbO₃) samples. Reprinted from Ref. [31].

Fig. 9. (Color online) (a) External quantum yield spectra measured for BFO electrodes before poling and after + 8 and –8 V poling. (b) Photocurrent-potential characteristics of the photoelectrodes with different polarization states. Schematic illustrations of the mechanisms in photoexcited charge transfer from BFO films to the electrolyte and from excited surface modifiers to the BFO films after the BFO films were (c) positively and (d) negatively poled. Reprinted from Ref. [99]. (e, f) Schematic electronic band structure and the mechanisms for the injected hot-electron transfer from PZT films to the electrolyte for the two poling configurations. Reprinted from Ref. [101].

Fig. 10. (Color online) Schematic illustration of the (a) electron–hole separation of La₂Ti₂O₇/LaCrO₃ heterojunction and (b) g-C₃N₄/SrTiO₃:Rh composite under visible light irradiation. Reprinted from Refs. [111, 113], respectively.

Fig. 11. (Color online) (a) Synthesis route of SrTiO₃/TiO₂ HoMs from hydrothermal reaction. (b) Typical time course of photocatalytic H₂ and O₂ evolution reaction of triple shelled SrTiO₃/TiO₂ HoMs photocatalyst. (c) Possible band structure diagram for SrTiO₃/TiO₂ HoMs. Reprinted from Ref. [118].

Fig. 12. (Color online) Schematic illustration of (a) the photogenerated charge transfer and catalytic reaction mechanisms of the fabricated LaCoO₃/Au nano-composite (Reprinted from Ref. [125]), and (b) the prepared Au/LTO NSP. (c) The diffuse reflectance spectra (left axis, blue line) and apparent quantum efficiency (right axis, red column) of Au-LTO NSP under vis-NIR (λ > 420 nm) light irradiation. Reprinted from Ref. [ 127].

Fig. 13. (Color online) (a) Schematics and cross-section of scanning electron microscope (SEM) of the fabricated ITO/PZT/Au, ITO/PZT/Au/PZT, and ITO/Au/PZT electrodes. (b) Top-view SEM image of nano-Au array fabricated on ITO glass; scale bar, 1 μm. The inset zooms in one part of the SEM; scale bar, 200 nm. (c) FDTD-simulated spatial distribution of the electric field intensity around the square dot illuminated by 800 nm light. (d) Photocurrent-potential measurements of ITO/nano-Au/PZT(black), ITO/PZT/nano-Au/PZT (red) and ITO/PZT/nano-Au (blue) under the white-light excitation (filtered, > 450 nm). (e) Photocurrent-potential measurements of the ITO/PZT/nano-Au/PZT (the as-grown (black), + 10 V (red) and –10 V (blue) poled) under the white-light excitation (filtered, > 450 nm). Reprinted from Ref. [ 101].