Ce ³⁺ /Ce ⁴⁺ Redox Shuttle Induces Spontaneous Ru Valence Transition in HKUST-1 for Dual Enhancement of H ₂ Activation and H* Release

The production of high-density aviation fuels via DCPD hydrogenation is critical, yet conventional catalysts frequently suffer from limited active site density and inefficient hydrogen spillover, leading to suboptimal activity. Herein, we report a “redox shuttle” strategy engineered within a Ce-incorporated Ru-HKUST-1 to overcome these challenges. By leveraging post-synthetic Ce exchange and thermal activation, we induce a Ce 3+ /Ce 4+ redox shuttle that facilitates electron release, generating a high abundance of coordinatively unsaturated Ru δ+ active sites. Furthermore, the coupling between Ce 4f and Ru 3d orbitals optimizes the electronic structure of Ru, thereby mitigating electron localization at the Ru−H bond and significantly lowering hydrogen migration barriers. Under mild conditions (room temperature, 0.5 MPa H 2, 20 min), our catalyst achieves complete DCPD conversion with ≥99.9% selectivity for THDCPD, maintaining activity over 15 consecutive cycles. Comprehensive experimental and theoretical analyses reveal a cooperative synergistic mechanism: Ce-mediated electron release promotes Ru δ+ formation, while electron backflow, driven by strong Ce−Ru orbital coupling, fine-tunes the electronic states of Ru sites, maximizing H 2 activation and H* migration efficiency. This work highlights the critical role of the redox shuttle effect in optimizing Ru sites, paving the way for advanced MOF-based catalysts in hydrogenation.