Alkaline‐earth metal Ca and N codoped TiO2 sheets with exposed {001} facets were obtained through a one‐step hydrothermal process. The codoped TiO2 appears as microsheets with length of 1–2 μm and thickness of 100–200 nm. The X‐ray diffractometer and X‐ray photoelectron spectroscopy results confirm that Ca and N codoped TiO2 has higher crystallinity than N‐doped TiO2, as well Ca, N atoms were successfully codoped into TiO2 as interstitial Ca and interstitial N or an O–Ti–N structure, respectively. Compared with N monodoped, further alkaline‐earth Ca codoped has little influence on the energy bands of TiO2 except slightly elevating the conduction band edge at a value of 0.02 eV. The hydroxyl radicals (•OH) producing and photocatalytic experiment shows that Ca and N codoped can effectively decrease the generation of recombination centers, and enhance separation efficiency of photo‐induced electrons and holes as well as the photocatalytic activity of TiO2. The codoped photocatalyst has the highest photocatalytic activity when Ca doped ratio reach 0.48%. Excess Ca doped will weaken the crystallization of anatase TiO2, form charge center, produce new recombination centers and finally reduce the photocatalytic activity of TiO2.

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In this work, we demonstrate a novel approach to control the photocatalytic selectivity of TiO 2 though different dominant crystal facets. {101}, {111}, and {001} facets exposed nanoscale anatase TiO 2 were obtained by a simple hydrothermal route with different ratio of NH 4 + and F -, then a calcined progress to clear surface adsorbent atoms. Results reveal that {101} exposed TiO 2 has some remain binding N with a mode of unsaturated N 3c exhibits selectively photocatalytic degradation of methylene orange (MO) in a methylene blue (MB) and methyl orange (MO) mixed solution, whereas TiO 2 with exposed {111} and {001} facets exhibits photocatalytic selectivity for MB. The {111} facets of anatase TiO 2 exhibit a better photocatalytic selective ability than {001} facets. It confirms that the photocatalytic selectivity can be affected by different dominant crystal facets. In a deeper analysis, there are many unsaturated O 2c on the surface of {001} and {111} facets, which enhances adsorbent selectivity and relevant photocatalytic activity of MB, at the same time, the unsaturated O 2c on the surface of {111} facets is much more than that on the surface of {001} facets results in a better photocatalytic selectivity of {111} facets. This research hopes that developing a new strategy for photocatalytic selectivity and providing a deeper understanding of different crystal facets of TiO 2 .

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