Interfacial interaction-dependent in situ restructure of NiO/TiO2 photocatalysts

[Display omitted] •Series NiO/TiO2 photocatalysts were prepared via an ion exchange method.•The NiO-TiO2 interfacial interaction strongly influences in situ restructure processes of NiO in NiO/TiO2 photocatalysts.•The higher and stable photocatalytic activity attributed to the strong NiO-TiO2 interfacial interaction.•Superabundant NiO nanoparticles are reduced to Ni resulting enhanced photocatalytic activity. Composite photocatalysts often undergo in situ restructure during photocatalytic reactions. Herein we report that the NiO-TiO2 interfacial interaction of NiO/TiO2 photocatalysts prepared via an ion exchange method strongly influences in situ restructure processes. With the Ni loading increasing, TiO2 supported NiO nanoparticles, TiO2 (core)-NiO (ultrathin shell) and TiO2 (core)-NiO (ultrathin shell) supported NiO nanoparticles are acquired sequentially. During photocatalytic water reduction reaction, TiO2 supported NiO nanoparticles and TiO2 (core)-NiO (ultrathin shell) are stable due to strong NiO-TiO2 interfacial interaction, whereas NiO nanoparticles supported on TiO2 (core)-NiO (ultrathin shell) are reduced to Ni nanoparticles, resulting enhanced photocatalytic activity. These findings bridge heterogeneous thermocatalysis and photocatalysis with the phenomenon of interfacial interaction-dependent in situ restructure.