Crystal-plane-dependent metal oxide-support interaction in CeO2/g-C3N4 for photocatalytic hydrogen evolution

CeO2 and its derivatives are potential photocatalysts due to their superior redox ability, abundant oxygen defects and cost effectiveness. However, little attention has been paid to the crystal-plane-dependent interactions in CeO2-based nanocomposites for photocatalytic hydrogen evolution. In this work, CeO2/g-C3N4 were synthesized with tunable CeO2 crystal planes ({110}, {100}, and {111}). Photoelectrochemical, XPS, Raman, ESR results suggested that the electron-separation efficiency, oxygen defects and Ce3+/Ce4+ reversibility pairs were greatly dependent on the crystal-faceted CeO2 and g-C3N4 interaction, and the photocatalytic performances of hydrogen evolution under visible light irradiation were in the order: CeO2{110}/g-C3N4 > CeO2{100}/g-C3N4 > CeO2{111}/g-C3N4 > g-C3N4. Furthermore, the FT-IR, XPS and density functional theory (DFT) calculations shown that the different properties of CeO2/g-C3N4 were resulted from the built-in electric field at the interface, and more intensive electronic interaction was found on CeO2{110}/g-C3N4, leading to the efficient separation and transfer of photo-generated electrons under light illumination.