Electron-DeficientCo^δ+ Induced bySynergistic Co–ZnO–ZnAl₂O₄ InterfaceInteractions for Enhanced <i>N</i>‑PropylcarbazoleHydrogenation

Developing efficient and cost-effective hydrogenation catalysts is essential for advancing liquid organic hydrogen carrier (LOHC) technology. In this study, ZnO-modified Co/Al₂O₃ catalysts were synthesized via coprecipitation and evaluated for <i>N</i>-propylcarbazole (NPCZ) hydrogenation. Among them, Co₅₀Zn₂Al₈ achieved complete hydrogenation within 60 min under mild conditions (150 °C, 7 MPa), demonstrating outstanding activity. This performance is attributed to the synergistic Co–ZnO–ZnAl₂O₄ interface, which induces electron transfer from Co to ZnO, generating electron-deficient Co^δ+ species. These species enhance hydrogen dissociation and NPCZ adsorption, accelerating the reaction. ZnO also forms a protective layer around Co particles, preventing strong Co–Al₂O₃ interactions and suppressing inactive CoAl₂O₄ formation, thereby improving the Co reducibility and dispersion. Advanced characterization and density functional theory calculations provided insights into the electronic and structural effects of ZnO on the catalytic mechanism. Stability tests confirmed that Co₅₀Zn₂Al₈ retained high activity over five cycles without significant deactivation. The synergistic Co–ZnO interaction reduces the activation energy and improves reaction rates, making Co₅₀Zn₂Al₈ a highly efficient and durable catalyst. With its low cost, high activity, and remarkable stability, Co₅₀Zn₂Al₈ shows great potential for LOHC hydrogenation, offering a promising pathway for efficient hydrogen storage and utilization.