Pentavalent Uranium-Regulated U-Co-Ru Ternary Oxide: High-Efficient Electrocatalyst for Water Splitting.

RuO2 currently serves as a highly advantageous catalyst for water electrolysis. Nonetheless, unstable hypervalent Ru species during the oxidation process can lead to catalyst inactivation. Herein, we report the successful construction of pentavalent uranium-regulated U-Co-Ru ternary oxide with alterable valence states and stable coordination. The dual doping with U and Co significantly enhanced the activity for water splitting in multiple environments, such as acidic, alkaline, and seawater media. The alkaline oxygen evolution reaction could be driven by only 257 and 366 mV at 100 mA cm-2 and 1 A cm-2, respectively. The results of in situ X-ray absorption fine structure analysis revealed that the U-site could act as an interatomic spring and flexibly adapt to the electron transfer through dynamically adjusted U-O bonds and valence state variation. This work represents a path for depleted uranium utilization and, for the first time, elucidates the evolution of pentavalent uranium in the OER processes by synchrotron radiation-based in situ techniques.