Enhancing the photocatalytic performance of g-C3N4 by using iron single-atom doping for the reduction of U(VI) in aqueous solutions

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-C3N4) 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-C3N4. The optimum Fe-CN photocatalyst with an Fe:C3N4 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.