New Strategy for the Persistent Photocatalytic Reduction of U(VI): Utilization and Storage of Solar Energy in K⁺ and Cyano Co‐Decorated Poly(Heptazine Imide)

The photocatalytic conversion of soluble U(VI) into insoluble U(IV) is a robust strategy to harvest aqueous uranium, but remains challenging owing to the intermittent availability of solar influx and reoxidation of U(IV) without illumination. Herein, a dual platform based on K + and cyano group co‐decorated poly(heptazine imide) (K‐CN‐PHI) is reported that can drive persistent U(VI) extraction upon/beyond light. K‐CN‐PHI achieves the photocatalytic reduction of U(VI) with a reaction rate of 0.89 min −1 , being 47 times greater than that over pristine carbon nitride (PCN). This system can further be triggered by light to form long‐living radicals, driving the reduction of U(VI) in the dark for over 3 d. The flexible structural K + as counterions stabilize the electrons trapped by cyanamide groups, enabling the long lifetime of the generated radicals. The results collectively prove K‐CN‐PHI to be a novel and efficient photocatalyst enabling persistent U(VI) extraction around the clock, and broadening the practical applications of the photocatalytic extraction of U(VI).