Author Affiliations
1Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China3School of Mathematical Science and Engineering, Hebei University of Engineering, Handan 056038, Chinashow less
Fig. 1. (Color online) PEC water splitting in (a) the n-type semiconductor-based PEC system, (b) p-type semiconductor-based PEC system, and (c) tandem system[6].
Fig. 2. (Color online) Main processes of PEC water splitting for n-type semiconductors.
Fig. 3. (Color online) (a) ZnO model of the hexagonal wurtzite structure, (b) schematic illustrations of atoms and charges distribution in the unit cell of Wurlitzer-structure ZnO, where F and P represent the applied stress and the induced electric dipole moment, respectively[11].
Fig. 4. (Color online) Energy potentials of ZnO and redox potentials for PEC water splitting at pH = 7, relative to NHE (normal hydrogen electrode).
Fig. 5. (Color online) Carrier transport mechanism of the ZnO photoanode.
Fig. 6. (Color online) Schematic illustration of the preparation processes of CS ZnO/TiO2 and BN ZnO/TiO2[24].
Fig. 7. (Color online) Effect of element doping on band structure[27].
Fig. 8. (Color online) (a) Schematic diagram of N gradient doped ZnO nanorods and stepped band structure to promote carrier separation[15]. (b) Morphological benefits of Y doping and schematic of increased electron mobility from trap filling[30].
Fig. 9. (Color online) Schematic diagrams of the forms of (a) type-II junction, (b) p–n junction, (c) Z-scheme system, and (d) hot-electron injection[3].
Fig. 10. (Color online) Schematic illustration of the proposed mechanism for the charge transfer (a) in ZnWO4/ZnO photoanode[31], (b) between ZnO and MoSx co-catalyst[32], (c) for the system of ZnO/CdS/PbS ONTs[19], and (d) ZnO–Au–SnO2[34].
Fig. 11. (Color online) (a) Bilateral CdS–ZnO–ZnO–CdSe nanowire array photoanode structure and corresponding energy level diagram[37]. (b) Synthetic route diagram and (c) schematic of the potential energy diagram of the ZnO/ZnFe2O4/PbS nanorod arrays electrode[38].
Fig. 12. (Color online) (a) The main mechanism of Au/3D ZnO nanowire photoelectrode[40]. (b) Schematic diagram of bending the sample to bending radius R under light[41].
Fig. 13. (Color online) Schematic band alignment of charge transport and recombination models in (a) ZnO and (b) FVO/ZnO photoanodes[48].
Fig. 14. (Color online) Piezo-phototronic effect on the photoelectrocatalytic process (photoanode). Illustration of the photoelectrocatalytic process (a) without strain, (b) under tensile strain, and (c) under compressive strain[11].
Fig. 15. (Color online) Schematic illustration of the enhanced catalytic performance induced by piezotronic effect and unique asymmetric nanostructure under light irradiation and ultrasonic actuation (ϕSB, Schottky barrier; ECB and EVB, the CB and VB of ZnO, respectively; Ef, the Fermi level of the Asy–Au–ZnO composite structure)[53].