This study presents a novel approach to recover uranium from spent fuel reprocessing wastewater using S-scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts. The design of these heterojunctions is based on the built-in electric field and energy band bending theory, which enhances the immobilization of hexavalent uranium (U(VI)) into relatively insoluble tetravalent uranium (U(IV)). The photocatalysts exhibit high removal and recovery ratios of U(VI) in wastewater, reaching 93.38% and 83.58%, respectively. The C3N5/Fe2O3 heterojunctions demonstrate excellent catalytic activity and selectivity even in the presence of excessive impurity cations and various organics. The strong redox activity and carrier separation efficiency of the heterojunctions are attributed to the internal electric field and Coulomb attraction, which prevent carrier recombination and enhance the photocatalytic performance. The study provides a potential solution for the effective purification of nuclear wastewater and the recovery of strategic resources.This study presents a novel approach to recover uranium from spent fuel reprocessing wastewater using S-scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts. The design of these heterojunctions is based on the built-in electric field and energy band bending theory, which enhances the immobilization of hexavalent uranium (U(VI)) into relatively insoluble tetravalent uranium (U(IV)). The photocatalysts exhibit high removal and recovery ratios of U(VI) in wastewater, reaching 93.38% and 83.58%, respectively. The C3N5/Fe2O3 heterojunctions demonstrate excellent catalytic activity and selectivity even in the presence of excessive impurity cations and various organics. The strong redox activity and carrier separation efficiency of the heterojunctions are attributed to the internal electric field and Coulomb attraction, which prevent carrier recombination and enhance the photocatalytic performance. The study provides a potential solution for the effective purification of nuclear wastewater and the recovery of strategic resources.