Accelerating urea oxidation kinetics by inducing Ru spin transitions in Y2Ru2O7 via 4f–2p–4d gradient orbital coupling

Urea oxidation reaction (UOR) kinetics is severely limited by suboptimal intermediate adsorption, which can be significantly improved by modulating catalyst spin configurations. Herein, we report an effective strategy for reforming the Ru spin configuration in pyrochlore oxide Y 2 Ru 2 O 7 (YRO) to enhance UOR performance through gradient orbital coupling. By partially substituting Y with Sm, we precisely regulate the electronic structure of candidate Y 1.9 Sm 0.1 Ru 2 O 7 (YRO-Sm), transforming Ru spin configuration from the low spin to the high spin (HS) configuration. The HS configuration endows YRO-Sm with excellent UOR activity (1.43 V at j  = 100 mA cm −2 ) and robust stability. Theoretical analysis reveals that Sm substitution leads to a significant Sm(4 f)–O(2p)–Ru(4d) orbital electron coupling effect. The highly degenerate 4 f orbitals of Sm enhance Ru–O covalency and Ru electron localization in YRO-Sm, facilitating *COO intermediate dissociation and thereby lowering the energy barrier for UOR. The practical potential of YRO-Sm was further demonstrated through its successful integration into both a hybrid water electrolyzer for energy-saving hydrogen production and a urea-assisted zinc–air battery. This work demonstrates a promising pathway for developing high-performance pyrochlore catalysts via spin state engineering for sustainable energy conversion applications.