Solution chemistry quasi-epitaxial growth of atomic CaTiO perovskite layers to stabilize and passivate TiO photoelectrodes for efficient water splitting.

Perovskite oxides with unique crystal structures and high defect tolerance are promising as atomic surface passivation layers for photoelectrodes for efficient and stable water splitting. However, controllably depositing and crystalizing perovskite-type metal oxides at the atomic level remains challenging, as they usually crystalize at higher temperatures than regular metal oxides. Here, we report a mild solution chemistry approach for the quasi-epitaxial growth of an atomic CaTiO perovskite layer on rutile TiO nanorod arrays. The high-temperature crystallization of CaTiO perovskite is overcome by a sequential hydrothermal conversion of the atomic amorphous TiO layer to CaTiO perovskite. The atomic quasi-epitaxial CaTiO layer passivated TiO nanorod arrays exhibit more efficient interface charge transfer and high photoelectrochemical performance for water splitting. Such a mild solution-based approach for the quasi-epitaxial growth of atomic metal oxide perovskite layers could be a promising strategy for both fabricating atomic perovskite layers and improving their photoelectrochemical properties.