Facet-dependent catalytic activities of Pd/rGO: Exploring dehydrogenation mechanism of dodecahydro-N-ethylcarbazole.

• Pd nanoparticles enclosed by {100}, {110} and {111} facets were successfully synthesized in-situ on rGO. • Facet effect in the dehydrogenation of LOHC was proposed for the first time. • Restriction mechanism of the macrokinetic and thermodynamic rate-determining step was preliminarily discussed. Facet structure plays an important role in many reactions. Generally, dehydrogenation reactions with only C H bond cleavage are often considered as structure insensitive reactions and therefore, there is no report on facet effect in reactions of LOHC for now. Herein, we report a facile synthesis of Pd nanoparticles enclosed by {100}, {110} and {111} facets supported on reduced graphene oxide. Combined with catalyst characterization, dehydrogenation performance study and DFT calculations, we found that the conversion rate and selectivity were strongly correlated with the facet structure of Pd, and {100} facet exhibited superior activity. We also identified the rate-determining step in the dehydrogenation of tetrahydro-N-ethylcarbazole to N-ethylcarbazole on Pd {100} facet. This work provides a basis for research requiring template Pd catalysts on rGO and broaden design methods for LOHC catalysts. [ABSTRACT FROM AUTHOR]