Photocatalysis is regarded as a safe, efficient, and environmentally-friendly method for treating uranium-containing waste water. In this work, novel Fe-doped graphitic carbon nitride (g-C 3 N 4) photocatalysts (Fe-CN) were synthesized by using molten salts and reflux method. They were characterized by various techniques, including XPS, IR, SEM, UV–Vis, EIS, and PL. To evaluate the photocatalytic reduction of U(VI) under visible light irradiation, various influencing factors were systematically investigated. The results showed that all Fe-CN samples exhibited significantly greater photocatalytic activity than pristine g-C 3 N 4. The optimum Fe-CN photocatalyst with an Fe:C 3 N 4 molar ratio of 1: 10.6 (Fe-CN-3) had the highest photocatalytic performance with a photocatalytic reduction efficiency of U(VI) that reached 96% after 240 min irradiation. Fe-CN-3 presented good reusability, demonstrating its promising applications for treating radioactive contaminants. A novel Fe-doped graphitized carbon nitride (g-C 3 N 4) photocatalyst (Fe-CN-x) was prepared by molten salt method and reflow method, and demonstrated its excellent photoelectrochemical and photocatalytic performance. Compared with pure g-C 3 N 4 , the photoreduction activity of Fe-CN-x composites is significantly enhanced. Fe single atoms can accelerate the interfacial charge transfer process on the g-C 3 N 4 surface. It has good reusability, demonstrating its promising applications for treating radioactive contaminants. [Display omitted] • A novel composite of g-C 3 N 4 doped iron single-atom was prepared for photocatalytic reduction of U(VI). • Single-site iron atoms can accelerate the interfacial charge transfer process on the surface of g-C 3 N 4. • Fe-CN-3 exhibited excellent photocatalytic activity and stability for removal of U (VI). • The photocatalysis mechanism of Fe-CN-3 was discussed. [ABSTRACT FROM AUTHOR]