• Facet engineered Fe/TiO 2 was used as photocatalyst for persulfate activation. • The band gap of the prepared Fe-{0 0 1}TiO 2 nanocatalyst was decreased from 3.24 eV to 2.97 eV. • The degradation efficiency of 3 % Fe/{0 0 1}TiO 2 was 97.81 % for 80 min. • OH, SO 4 − , e − and h + were contributed to the degradation in photo-synergetic persulfate system. • Fe-{0 0 1}TiO 2 exhibited excellent stability even after five consecutive cycles. Photo-synergetic persulfate oxidation is a prospective technology for water decontamination. Understanding the engineering facet activity of TiO 2 based nanocatalyst for persulfate (PS) activation is vital. Herein, Fe-doped TiO 2 nanocrystal with {0 0 1} crystal face exposed (Fe/TiO 2 ) is used to improve the degradation efficiency of Rhodamine B (RhB). The experimental results show that the Fe is introduced into the TiO 2 lattice, resulting in abundant surface oxygen vacancies in Fe/TiO 2 nanocrystal. The band gap of the as-prepared nanocatalyst was reduced from 3.24 eV to 2.97 eV. The degradation efficiency of RhB (10 mg/L) reaches 97.81 % after 80 min reaction. The enhanced catalytic performance benefits from the synergistic effect of enhanced visible light absorption and persulfate activation. OH, SO 4 − , e − and h + are proved to contribute to the degradation of RhB. This work presents a new opportunity to improve the efficiency of photo-synergetic persulfate oxidation by Fe doped TiO 2 .