Engineering\nof a N‑Doped Anatase/Rutile TiO<sub>2</sub> Heterophase Junction\nvia In Situ Phase Growth for Photocatalytic\nHydrogen Evolution

N-doped anatase/rutile TiO<sub>2</sub> (AR-N/TiO<sub>2</sub>) photocatalysts\nwere prepared by combining the strategy of N-doping and in situ heterophase\njunction generation, which significantly enhanced the photocatalytic\nH<sub>2</sub> generation (1.68 mmol· h<sup>–1</sup>·g<sup>–1</sup>). Under monochromatic light at 400 nm, the light\nexhibits an apparent quantum efficiency of 8.6%. Moreover, this AR-N/TiO<sub>2</sub> heterophase junction demonstrates excellent long-term stability\nwhen exposed to visible light irradiation. Through the analysis of\nthe electronic structure, the outstanding photocatalytic activity\nof AR-N/TiO<sub>2</sub> can be attributed to the maximized synergetic\neffect between rutile and anatase for optimal rutile content (21.6%)\nand enhanced response to visible light due to N-doping. Additionally,\nthe intimate interface formed by the rutile phase grown in situ from\nthe inner core of the anatase phase establishes well-aligned bands,\nwhich promote efficient separation of photoinduced electron–hole\npairs. Furthermore, the rough surface and porosity of the as-synthesized\nheterophase junction facilitate an enlarged specific surface area\nand exposure of active sites, thereby providing more adsorptive and\nreactive sites that enhance conversion efficiency. This research offers\nan alternative approach to phase engineering for developing TiO<sub>2</sub>-based heterophase junction photocatalysts toward efficient\nhydrogen evolution.