Cold-Plasma-Engineered CeO2–Carbon Interfaces Unlock Pdδ+/Pd0 Synergy for Ultrafast and Deep LOHC Dehydrogenation

To overcome the activity and durability bottlenecks of Pd catalysts in the deep dehydrogenation of liquid organic hydrogen carriers (LOHCs), we couple dielectric-barrier cold plasma with CeO2 modulation. This green, low-energy cold-plasma process treats a Ce-doped Pd/C precursor at near-room temperature, redistributing the oxide and constructing a stable CeO2-carbon (CeO2–C) interface, and drives Pd nanoparticles to anchor at this interface, generating electron-deficient Pdδ+ sites in intimate contact with Pd0. Structure-performance correlations show that the new interface greatly increases Pd dispersion and Lewis-acid site density, while the Pdδ+ centers, through concurrent electronic withdrawal and acidity enhancement, accelerate the rate-determining 4H-NPCZ → NPCZ step. Consequently, with a catalyst mass fraction of 20 wt %, PdCe5C–Ar achieves complete dehydrogenation of fully hydrogenated N-propylcarbazole (12H-NPCZ) within 240 min at 180 °C and delivers a mass-specific hydrogen-release rate of 223.0 mmol H2 gmetal–1 min–1─almost twice the best literature value─while retaining full activity after eight cycles. DFT calculations attribute the performance leap to a downward shift of the Pd d-band center and to a lowered third-step barrier (ΔH3 = 2.381 eV) induced by Pdδ+. This work is the first to apply low-temperature plasma interface engineering to a Pd-CeO2–C ternary system, offering a broadly applicable paradigm for low-Pd, high-efficiency, long-life LOHC dehydrogenation catalysts.