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

• Series NiO/TiO 2 photocatalysts were prepared via an ion exchange method. • The NiO-TiO 2 interfacial interaction strongly influences in situ restructure processes of NiO in NiO/TiO 2 photocatalysts. • The higher and stable photocatalytic activity attributed to the strong NiO-TiO 2 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-TiO 2 interfacial interaction of NiO/TiO 2 photocatalysts prepared via an ion exchange method strongly influences in situ restructure processes. With the Ni loading increasing, TiO 2 supported NiO nanoparticles, TiO 2 (core)-NiO (ultrathin shell) and TiO 2 (core)-NiO (ultrathin shell) supported NiO nanoparticles are acquired sequentially. During photocatalytic water reduction reaction, TiO 2 supported NiO nanoparticles and TiO 2 (core)-NiO (ultrathin shell) are stable due to strong NiO-TiO 2 interfacial interaction, whereas NiO nanoparticles supported on TiO 2 (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.