Cold-Plasma-Engineered CeO ₂ –Carbon Interfaces Unlock Pd ^δ+ /Pd ⁰ 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.