Boosting the hydrogen production efficiency of dodecahydro-N-ethylcarbazole by depositing Pd on the accordion-like C₃N₄

N-ethylcarbazole/Dodecahydro-N-ethylcarbazole (NECZ/12H-NECZ) has emerged as a highly promising candidate among liquid organic hydrogen carriers (LOHCs), however, the relatively slow dehydrogenation kinetic and low selectivity render the commercial applications. Herein, an accordion-like C₃N₄ with expanded interlayer spacing and abundant carbon vacancies is synthesized via a mixed-alcohol-assisted bottom-up method. The optimal Pd/EN-C₃N₄ catalyst (EN-C₃N₄ denotes accordion-like C₃N₄ treated by ethanol and n-butanol intercalation) exhibited excellent performance, achieving 99.43% conversion and 5.0 wt% H₂ release in 90 min at 453 K. Characterization and DFT calculations reveal that the unique accordion structure provides high specific surface area and abundant carbon vacancies, which improves the dispersion and anchoring stability of Pd NPs. Meawhile, the carbon vacancies increase electron density around Pd nanoparticles and upshift the d-band center, collectively reducing the energy barrier of the rate-determining step. The catalyst also demonstrates excellent stability over 49 h. This work provides a defect-engineering strategy for designing efficient LOHC dehydrogenation catalysts.