N  +  Ni Codoped Anatase TiO ₂ Nanocrystals with Exposed {001} Facets Through Two‐Step Hydrothermal Route

This study introduces a facile and novel route to synthesize the N + Ni codoped anatase TiO 2 nanocrystals with exposed {001} facets through two‐step hydrothermal reaction. The microstructures, chemical compositions, and photocatalytic properties of the codoped TiO 2 were characterized using X ‐ray diffractometer, high‐resolution transmission electron microscopy, X ‐ray photoelectron spectroscopy, UV ‐vis spectrometry, and photoluminescence emission spectra. The experimental results revealed that (i) the elements N and Ni have been successfully codoped into the anatase TiO 2 with exposed {001} facets; (ii) the size of the TiO 2 reached to a narrow range of 5–15 nm; (iii) the codoped TiO 2 exhibited an additional visible light absorption band from 400 to 500 nm, which greatly improved the photocatalytic activity. The theoretical calculations for band structure and total energy also provided a good explanation for the experimental results.