Pengyang Jiang,Baoxin Ge,Jiaqing Liu,Caijin Huang,Xue Feng Lu
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.
Jinhui Zhang,Lei Shi,Xianbing Miao,Shiming Zhou,Liping Yang
For acid–water oxidation, pyrochloric ruthenates are thought to be extremely effective electrocatalysts. In this work, through partial B-site replacement with larger M2+ cations, the electronic states of Y2Ru2O7 with strong electron correlations are reasonably managed, by which the inherent performance is tremendously promoted. Based on this, the improved Y2Ru1.9Sr0.1O7 electrocatalyst exhibits an outstanding durability and presents a highly inherent mass activity of 1915.1 A gRu–1 (at 1.53 V vs RHE). The enhanced oxygen-evolving reaction (OER) activity by ionic dopant in YRO pyrochlore can be attributed to two aspects, i.e., the lattice distortion induced inhibition of the grain coarsening, which results in a large surface area for YRO-M and increases the OER active sites, and the weakening of electron correlation via broadening of the Ru 4d bandwidths due to the increase of the average radius of B-site ions, which gives rise to an enhancement of conductivity and a strengthened hybridization between Ru 4d and O 2p orbitals and improves the reaction kinetics. The synergistic effects of lattice distortion and orbital hybridization promote the enhanced OER activity. The results would provide fresh concepts for the design of improved electrocatalysts and underscore the significance of managing the intrinsic performance through the dual modification of microstructure morphology and electronic structure.
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