Modulating adsorption sites and molecular dipole moment via synergistic K/S co-doping and cyano grafting on g-C₃N₄ for boosted photocatalytic U(VI) extraction

Photocatalytic extraction of uranium from wastewater presents an attractive route for environmental remediation as well as sustainable nuclear energy, aligning with the carbon peaking and carbon neutrality goals. However, conventional g-C₃N₄-based photocatalytic systems suffer from fast electron-hole recombination. To address the challenge, this work innovatively constructed a photocatalytic material using a strategy of K/S co-doping coupled with cyano functionalization. It demonstrated superior U(VI) photocatalytic extraction efficiency, strong anti-interference capability against coexisting ions and excellent recyclability. An extraction efficiency of 95.7% for U(VI) was attained without any sacrificial agent or protective gas. The results indicated the synergy of K/S doping combined with cyano functionalization tailored the band structure and generated high localized electron density. The large molecular dipole induced a built-in electric field (BEF) promoting oriented photo-excited electron movement and thereby enhancing U(VI) photocatalytic extraction. Ultimately, U(VI) ions were enriched on the photocatalyst via deposition of (UO 2 )O 2 ·2H 2 O, driven synergistically by photogenerated electrons and ·O₂ − . This research presents a novel and effective approach for recovering uranium resources from wastewater through photocatalysis.