N plus Ni Codoped Anatase TiO2 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 TiO2 nanocrystals with exposed {001} facets through two-step hydrothermal reaction. The microstructures, chemical compositions, and photocatalytic properties of the codoped TiO2 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 TiO2 with exposed {001} facets; (ii) the size of the TiO2 reached to a narrow range of 515 nm; (iii) the codoped TiO2 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.