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 CeO 2 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 CeO 2 -carbon (CeO 2 –C) interface, and drives Pd nanoparticles to anchor at this interface, generating electron-deficient Pd δ+ sites in intimate contact with Pd 0 . Structure-performance correlations show that the new interface greatly increases Pd dispersion and Lewis-acid site density, while the Pd δ+ 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 %, PdCe 5 C–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 H 2 g metal –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 (Δ H 3 = 2.381 eV) induced by Pd δ+ . This work is the first to apply low-temperature plasma interface engineering to a Pd-CeO 2 –C ternary system, offering a broadly applicable paradigm for low-Pd, high-efficiency, long-life LOHC dehydrogenation catalysts.